Pescatarian Diet

Diet Reference Archive: a diet

Pescatarian Diet

A way of eating that leaves out meat and poultry but includes fish and other seafood, usually along with eggs and dairy foods. People choose it for health, ethical, environmental or cultural reasons, and the American Heart Association lists it among the eating patterns that can support heart health.

Family: Plant-based and plant-forward diets Promoted by: no single founder in the sources opened; the American Heart Association lists it among heart-healthy patterns First appeared: the word by 1991; fish eaters studied in cohorts recruited from 1980 GRADE: Low for lower rates of ischemic heart disease in adults who eat fish but no meat, compared with meat eaters, over about 8 to 18 years in 2 UK cohort studies; this page's own judgment

ON THIS PAGE

1. In brief
2. Overview
3. In practice
4. For the coach
5. The evidence (opens on request)
6. Mechanisms (opens on request)
7. Risks, contraindications and myths (opens on request)
8. Key terms
9. Review questions
10. References
11. Evidence rating and review record

The summary and sections 1 to 3 are the short version and are open when the page loads. Sections 4 to 6 hold the research detail, the biology, and the cautions. Each of those opens when you select its heading, and you can read the page without opening them. The evidence on this diet is thinner than for the most studied patterns, so this page is shorter than most full diet pages. Back to the Diet Reference Archive index.

In brief

What is it? A pescatarian eats fish and other seafood but no meat or poultry. Most pescatarians also eat eggs and dairy foods, although the sources define that part differently.

Does it work? The searches for this page did not identify a long trial measuring heart attacks, cancer or death. What exists are large studies of people who already ate this way. In 2 British cohorts, fish eaters had somewhat lower rates of ischemic heart disease than meat eaters, about 6 fewer cases per 1,000 people over 10 years in one of them (Tong et al., 2019; Petermann-Rocha et al., 2021). A pooled analysis of 9 cohorts linked the pattern with a lower rate of colorectal cancer (Dunneram et al., 2026). For death from any cause, the mortality estimates generally favor a lower rate, but several are too imprecise to distinguish that from no difference (Mihrshahi et al., 2017; Orlich et al., 2013). These are associations, not proof that the diet caused them, and every rating on this page is low or very low.

Is it safe? For most adults it is one of the eating patterns the American Heart Association says can support heart health (Lichtenstein et al., 2026). Two cautions matter most. Some fish are high in mercury, so the U.S. Food and Drug Administration and the Environmental Protection Agency advise people who are or might become pregnant, people who are breastfeeding, and parents feeding children, to choose fish lower in mercury and to avoid a short list of the highest-mercury fish (U.S. Food and Drug Administration, n.d.). And leaving out meat does not by itself make a diet healthy: a pattern built on fried fish and refined foods is not the pattern the research describes (Gardner et al., 2023).

Who should not do it without talking to a doctor or dietitian first? Anyone who is pregnant, breastfeeding or planning a pregnancy; a parent planning this diet for a young child; a person with kidney disease; a person taking warfarin or another blood thinner who wants to add fish oil supplements; and a person with a current or past eating disorder.

Related pages: Mediterranean Diet, DASH Diet. The rest of the plant-based family is covered on the Vegetarian Diet, Vegan Diet, Flexitarian Diet and Whole-Food Plant-Based Diet pages. Full list on the archive index.

1. Overview

What you eat

A pescatarian diet is built on plant foods, such as vegetables, fruits, whole grains, beans and lentils, nuts and seeds, with fish and shellfish as the only animal flesh. The American Heart Association describes the pescetarian pattern as one that "excludes meat and poultry but includes fish; also usually includes dairy and eggs" (Gardner et al., 2023). Merriam-Webster lists pescetarian as a variant spelling (Merriam-Webster, n.d.).

The pattern sets no portions and no required amount of fish. How much fish people eat varies widely. Among more than 55,000 British adults in the EPIC-Oxford cohort, the 8,123 people who called themselves fish-eaters ate about as much fish as people who ate a small amount of meat, which the authors read as a sign that fish-eaters were not simply replacing meat with fish (Scarborough et al., 2023).

What you avoid or limit

Meat and poultry are left out: beef, pork, lamb, chicken, turkey and processed meats such as bacon, ham and sausages. The dictionary definition is "one whose diet includes fish but no other meat" (Merriam-Webster, n.d.). Eggs and dairy foods are usually kept, but the definitions differ on whether they must be.

Research studies draw the line in slightly different places, which matters when reading their results. The Adventist Health Study-2 counted people as pesco-vegetarians if they ate fish at least once a month and all other meats less than once a month (Orlich et al., 2013). The British EPIC-Oxford study counted people who ate fish but no meat (Tong et al., 2019). A pooled analysis of 9 cohorts defined pescatarians as people who ate no red meat, processed meat or poultry but did eat fish (Dunneram et al., 2026). The limit is a rule each person sets, and the studies classified people from what they reported at the start.

Where it came from

No clinical trial, book or company created this pattern in the sources opened for this page. People have long eaten fish without eating meat, and the word came later. Merriam-Webster traces pescatarian probably to the Italian pesce, fish, combined with the English word vegetarian, and dates its first known use to 1991 (Merriam-Webster, n.d.).

Researchers began following fish eaters as a separate group in cohort studies of vegetarians. The Oxford Vegetarian Study, which recruited from 1980 to 1984, included almost 1,000 people classified as pescatarians, and the larger EPIC-Oxford and Adventist Health Study-2 cohorts followed (Dunneram et al., 2026). Most of what is known about the diet comes from these studies of people who chose it themselves.

Cultural and philosophical context

People give health, ethical, environmental and religious reasons for eating this way. In a survey of college women, pesco-vegetarians rated ethical concern as more important in their food choices than omnivores did (Forestell et al., 2012). Religious practice shapes the pattern for some people. The Adventist Health Study-2 enrolled members of the Seventh-day Adventist church, which its researchers describe as a religious group that promotes vegetarianism and avoids certain meats and shellfish (Tonstad et al., 2013). This page rates the health claims made for the diet, not anyone's reasons for choosing it.

What it claims to do

The pattern has no single promoter, so its claims come from the people and organizations who discuss it. The American Heart Association states that a range of dietary patterns, "including healthy versions of commonly named diets when implemented as intended such as DASH (Dietary Approaches to Stop Hypertension), Mediterranean style, pescetarian, and ovo/lacto vegetarian, can support cardiovascular health and are aligned with achieving and maintaining a healthy body weight" (Lichtenstein et al., 2026). Clients also hear that the diet lowers the risk of cancer and that it is better for the planet. Section 4 reports what the research shows for each of these.

What it gets right

The pattern leaves out red and processed meat and keeps fish, and both moves line up with current heart-health guidance. The American Heart Association's 2026 statement advises regularly eating fish and seafood, noting that cohort studies have linked dietary patterns containing nonfried fish and seafood with fewer cardiovascular events and heart attacks (Lichtenstein et al., 2026). When the Association scored 10 popular patterns against its 2021 guidance, the pescetarian pattern was in the top tier, with DASH, Mediterranean and vegetarian patterns, when it is implemented as intended, rich in vegetables, fruits, whole grains and plant protein sources (Gardner et al., 2023). For a client who has chosen it, that is the part worth building on.

How clients describe it, and what it gets confused with

A client may say "I'm pescatarian," "I'm vegetarian but I eat fish," or "I only eat seafood." Each can mean a slightly different diet, so asking what the client includes comes first. In the Adventist research, "semi-vegetarian" meant eating some meat up to once a week, which is not the same as pescatarian (Orlich et al., 2013).

Several related patterns have pages of their own. The Vegetarian Diet page covers diets with no meat, poultry or fish. The Vegan Diet page covers diets that exclude fish and all other animal foods. The Flexitarian Diet page covers mostly plant diets with occasional meat, poultry or fish. The Whole-Food Plant-Based Diet page describes patterns defined mainly by whole or minimally processed plant foods rather than by whether fish or other animal foods are excluded. The Mediterranean Diet page describes a pattern with fish and shellfish 2 or 3 times a week that keeps poultry and red and processed meat low rather than leaving them out.

2. In practice

A typical day of eating

Breakfast might be oatmeal with milk or yogurt, berries and walnuts, or eggs on whole-grain toast. Lunch might be a bean and vegetable soup with bread, or a salad with canned tuna or sardines, chickpeas and an olive oil dressing. Dinner might be baked salmon or another fish with brown rice and roasted vegetables, or a lentil curry on nights without fish. Snacks might be fruit, nuts, cheese or hummus with vegetables. A day with no fish at all is still a pescatarian day; the pattern is defined by what is left out.

Cost, products, and who profits

A modeling study using food prices from 150 countries found that, among the healthy and sustainable patterns it tested, pescatarian versions were the least affordable, because fish had one of the highest prices per calorie in its price data. In high-income and upper-middle-income countries, every modeled pattern cost less than current diets except the pescatarian version high in vegetables and fruit (Springmann et al., 2021). These are modeled diets, not records of what pescatarians buy.

The American Heart Association notes that its top-tier patterns may raise spending on vegetables, fruits, nuts, fish and oils, and that herring, rainbow trout and some forms of tuna are more cost-effective fatty fish than salmon. It adds that frozen or canned produce can be as nutrient dense as fresh, and that legumes are a relatively low-cost source of protein (Gardner et al., 2023). No company or program owns the pattern in the sources opened for this page. Sellers of fish and seafood benefit when people eat this way, as do makers of omega-3 supplements such as fish oil, krill oil and algal oil (Office of Dietary Supplements, n.d.-c).

Environmental footprint

The best data come from linking what more than 55,000 people in the EPIC-Oxford cohort reported eating to environmental estimates from 570 life-cycle assessments, which estimate the impact of each food from production to sale. These are modeled impacts of measured diets, not impacts measured directly. Standardized to 2,000 kilocalories a day, fish-eaters' diets were linked with about 4.7 kilograms of greenhouse gas emissions a day, in carbon dioxide equivalents, against about 10.2 for people eating 100 grams of meat a day or more, 5.4 for people eating less than 50 grams of meat a day, and 4.2 for vegetarians. Land use followed the same order. Fish-eaters' water use matched that of the low meat-eaters (Scarborough et al., 2023).

Fish adds a pressure that land-based diets do not. The Food and Agriculture Organization of the United Nations reports that 37.7 percent of the marine fish stocks it assesses were fished at unsustainable levels in 2021, although stocks within sustainable levels supplied 76.9 percent of the landings from assessed stocks (Food and Agriculture Organization of the United Nations, 2024). How much any one pescatarian adds to that pressure depends on which fish they choose, where it comes from and how much of it they eat.

Cultural fit

Because the pattern keeps fish, eggs and dairy foods, it fits many food traditions with only the meat and poultry removed, and it leaves room for plant proteins from any cuisine. The American Heart Association notes that its top-tier patterns, including the pescetarian pattern, can be adapted to reflect personal and cultural preferences and budgets (Gardner et al., 2023), and its 2026 statement adds that understanding cultural factors, personal preferences, ethnic and religious practices, life stages and socioeconomic contributors can assist in counseling (Lichtenstein et al., 2026). It is harder to keep in households or communities where meals center on meat, or where fresh fish is costly or hard to find.

What makes people stop

This page's searches did not identify a study of why people stop eating a pescatarian diet. In one small trial of 5 diets for weight loss, including a pesco-vegetarian diet, no clear difference was detected between the groups in adherence or in changes in how acceptable participants found their diet over 6 months, a result read from the trial's abstract (Moore et al., 2015). People who stay with the pattern often stay a long time: in the Adventist Health Study-2, pesco-vegetarians reported following their pattern for 19 years on average (Orlich et al., 2013). Cost is the practical barrier the sources above describe. Other reasons a coach may hear, such as family meals or travel, were not found measured for this diet in this page's searches.

What happens when you stop

This page's searches did not identify a study that followed people after they left a pescatarian diet. Some participants in a small student study changed the extent of animal-food restriction over a year, but it did not establish health effects of stopping a pescatarian diet (Forestell et al., 2012). In EPIC-Oxford, people did move between diet groups over 5 years, and those who changed toward fewer animal foods gained the least weight on average (Rosell et al., 2006). The cohort results in section 4 describe people classified by their diet at the start of follow-up, so they cannot show what happens to someone who stops.

Common variations

Most pescatarians eat eggs and dairy foods, and some research calls this version pesco-vegetarian. Others leave out eggs, dairy or both. Some eat finfish but not shellfish, as many participants in the Adventist research did (Tonstad et al., 2013). A pescatarian diet built mostly on vegetables, legumes, whole grains, olive oil and fish overlaps heavily with the Mediterranean Diet, which keeps small amounts of poultry and meat.

3. For the coach

SCOPE OF PRACTICE

A health and wellness coach does not prescribe, adjust, endorse, or discourage a diet, and does not diagnose or treat. The coach helps the client understand what they have chosen, notice how it is going, and decide what to do next. With the client's permission, the coach can share general guidance from recognized authorities, such as the federal advice on choosing fish lower in mercury, and explore how the client wants to use it; the individual plan stays with the clinician. A pescatarian diet needs a registered dietitian or a physician when the client is pregnant, breastfeeding or planning a pregnancy, when it is being planned for a child, when the client has kidney disease or a history of an eating disorder, and whenever the question is which supplements to take.

Who does what

The physician

Decides whether a change in eating is medically appropriate for this person and adjusts any medication it affects. For a pescatarian diet that usually means nothing special for a healthy adult. It matters for a person taking warfarin who starts fish oil supplements, for the clotting-test monitoring described under medication interactions in section 6 (Office of Dietary Supplements, n.d.-c); for kidney disease, where needs depend on stage, lab results and dialysis; and in pregnancy, through the prenatal care team.

The registered dietitian

Designs and monitors an individual eating plan. For this diet, that typically means choosing fish lower in mercury in pregnancy, breastfeeding and childhood; checking that iodine, vitamin D, iron, zinc and long-chain omega-3 fats are covered when the client eats little fish or no eggs and dairy; and adapting the pattern to a diagnosed condition such as kidney disease.

The health and wellness coach

Helps the client see their own reasons for the diet, test it against their values and their real budget, schedule and household, and build the habits that make it workable, such as planning meals around fish, beans and vegetables, or finding affordable fish. The coach also helps the client notice how it is going and holds the referral line for the situations named above.

What a client bringing this diet needs

A client who says they are pescatarian is usually not asking whether to start. Many have eaten this way for years, and some are thinking about it for ethical or environmental reasons as much as for health. What the conversation can offer that a search engine cannot is clarity about which of those reasons matter most to them, an honest picture of what the research does and does not show, and a plan they own for the parts that are hard, such as cost, family meals, or knowing which fish to choose when pregnant.

What to ask

• "What drew you to eating fish but not meat, and what matters most to you about it?"
• "What does a usual week of meals look like for you, and where does fish fit in?"
• "What, if anything, would you like to be different about how this is working for you?"

Referral red flags

A coaching conversation becomes a referral when a client who eats this way is pregnant, breastfeeding or planning a pregnancy and has questions about which fish are safe or whether to take supplements; is planning the diet for a young child; has kidney disease; takes warfarin or another blood thinner and plans to start fish oil; reports fatigue, weakness or other symptoms the client is worried about; or loses weight without meaning to. Weight a person loses without meaning to can be a sign of a health problem and is a reason to involve a clinician, never a sign the diet is working. The coach does not try to work out the cause of a symptom; the client takes it to the clinician.

Eating behavior is a separate thread. Most people choose this diet for ordinary reasons, and a coach notices rather than assumes. The coach asks what a food rule is for, whether it causes distress, whether it is narrowing what the person eats, and whether it gets in the way of daily life. Where the answers raise a real concern about disordered eating, the coach follows their own referral process, and a client with an existing clinician or care plan takes the concern there.

Special populations

Pregnancy and breastfeeding

The FDA and EPA advise people who are or might become pregnant, and people who are breastfeeding, to eat 2 to 3 servings a week of fish from their "Best Choices" list, or 1 serving from the "Good Choices" list, with a serving of 4 ounces, and to avoid 7 fish with the highest mercury levels: king mackerel, marlin, orange roughy, shark, swordfish, tilefish from the Gulf of Mexico, and bigeye tuna (U.S. Food and Drug Administration, n.d.). This page's searches did not identify a trial of a pescatarian diet in pregnancy. Fish choices, supplements and any diet change belong to the prenatal care team and a registered dietitian.

Children and adolescents

For children, the FDA and EPA advise 2 servings a week from the "Best Choices" list, with a serving of about 1 ounce at ages 1 to 3, 2 ounces at 4 to 7, 3 ounces at 8 to 10, and 4 ounces at 11 (U.S. Food and Drug Administration, n.d.). A review of diets that restrict animal foods in childhood, read in its abstract, concluded that the more restrictive the diet and the younger the child, the greater the risk of nutritional deficiency (Chouraqui, 2023). In 165 Norwegian 16-to-24-year-olds, including pescatarians, urinary iodine suggested mild iodine deficiency in every diet group (Groufh-Jacobsen et al., 2024). This page's searches did not identify a trial in children. A child's diet is planned with the child's pediatrician and a registered dietitian.

Older adults

The fracture findings are mixed. In EPIC-Oxford, fish eaters had a higher rate of hip fracture than meat eaters, about 3 more cases per 1,000 people over 10 years (Tong et al., 2020), but in the UK Women's Cohort Study and UK Biobank pescatarians' hip fracture rates were not clearly different from regular meat eaters' (Webster et al., 2022, 2023). In the Adventist Health Study-2, the lower death rate among pesco-vegetarians was smaller at age 85 than at age 65 (Abris et al., 2024). Bone health and nutrient needs in older age go to the client's physician and a registered dietitian.

Athletes and people with high activity

This page's searches found only a cross-sectional study of body composition by diet group and sport, read in its abstract (Lombardo et al., 2024), and no trial of a pescatarian diet in athletes. Questions about fueling go to a sports dietitian.

People taking medication for diabetes, blood pressure, or blood thinning

Fish itself is not known to interact with these medications in the sources opened for this page. Fish oil supplements are different: at high doses they can affect clotting in people taking warfarin, as section 6 describes (Office of Dietary Supplements, n.d.-c). The archive's standing rule applies: a client on warfarin, insulin, sulfonylureas or blood pressure medication who plans a substantial change in eating keeps the prescriber informed before the change. If a client on insulin or a sulfonylurea reports shakiness, sweating or confusion, the first step is the one in their own plan for treating a low blood sugar episode, with emergency help if symptoms are severe or the episode is one they cannot manage; telling the prescriber is the separate step that follows.

People with a history of disordered eating

In a survey of 240 college women, the 28 pesco-vegetarians were not more restrained eaters than omnivores (Forestell et al., 2012); its results for women who avoided or limited red meat are on the Flexitarian Diet page. One small convenience sample of students is not evidence that this diet protects against eating disorders. Any diet that removes foods can become a vehicle for restriction, and a client with a current or past eating disorder considers this diet with their treatment team.

Client misconceptions

Three beliefs come up often. The first is that any diet with fish in it is heart healthy; the American Heart Association says the pattern is not inherently health promoting if it is made up mostly of fried fish or refined foods (Gardner et al., 2023). The second is that fish oil capsules do what eating fish does; the Association says fish oil supplementation alone has not been shown to lower cardiovascular risk in otherwise healthy adults (Lichtenstein et al., 2026). The third is that people who are pregnant should avoid fish altogether; the federal advice is to choose fish lower in mercury, not to avoid fish (U.S. Food and Drug Administration, n.d.).

🤝 COACHING CONNECTION

Maria tells her coach she stopped eating meat and chicken a few months ago for environmental reasons and now eats fish "when I can afford it," which is not often. She worries she is not eating well. The coach reflects that her reasons matter to her and that cost is getting in the way, and asks what her meals look like on the days without fish. Maria describes a lot of pasta and cheese. With her permission, the coach shares that the heart-health research describes this pattern with plenty of vegetables, beans and whole grains, and asks what she makes of that. Maria decides to try two bean-based dinners a week and to look at the price of canned fish, and she will report back on how it went.

4. The evidence

(select the heading to open or close this section)

Almost everything known about pescatarian diets comes from cohort studies that followed people who already ate this way. They link the pattern with lower rates of ischemic heart disease and colorectal cancer than among meat eaters, give mixed results for death from any cause, stroke and hip fracture, and cannot show that the diet itself caused any of these differences. The few randomized trials are small and short, from 2 weeks to 6 months, and measured mood, weight, laboratory markers, resting metabolism or physical function. The certainty ratings for each outcome are in the Evidence rating and review record at the end of the page.

Evidence from randomized controlled trials

A trial assigns people to the diet by chance and compares them with people assigned to something else, which is the strongest way to test whether the diet itself causes a result. Searches run October 4, 2026, and later checks of this page identified 3 randomized trials comparing a pescatarian diet with another diet, plus CEV-65, which compared a compatible dietary pattern with exercise or medication. None was designed to measure heart disease, cancer or death.

Cardiometabolic outcomes

In a 12-week trial in Florence, Italy, 113 healthy adults aged 18 to 50 were randomly assigned to a pesco-vegetarian diet with 3 servings of fish a week and no shellfish, a meat-based diet with about 900 grams of meat a week, or the same meat-based diet with a vitamin E supplement. Participants cooked their own meals from menus and counseling, and 103 finished. Changes in total, LDL and HDL cholesterol did not differ clearly between the diets. Ferritin, a measure of stored iron, and 2 markers of inflammation, interleukin-6 and tumor necrosis factor alpha, rose more on the meat-based diet than on the pesco-vegetarian diet (Dinu et al., 2025).

Cancer

The same trial's main outcome was a laboratory measure of DNA damage caused by stool water, used as a marker of colorectal cancer risk. DNA damage rose on the meat-based diet and did not change clearly on the pesco-vegetarian diet, but the results section reports that the difference between the diets did not reach statistical significance, although the discussion describes it as significantly greater. This page uses the results section. The stool marker of fat oxidation TBARS rose more in both meat-based groups than in the pesco-vegetarian group. The other marker, 4-HNE, rose more in the unsupplemented meat-based group (Dinu et al., 2025).

The authors state that these are short-term changes in markers that have not been validated as stand-ins for cancer, and should not be read as evidence of a change in cancer risk. The analysis included only the people who finished, the trial was open-label, and the pesco-vegetarian group that finished weighed less at the start, an average of 66.2 kilograms against about 75 in the other 2 groups (Dinu et al., 2025).

Body weight, as measured

In a 6-month trial in South Carolina, 63 adults with a body mass index of 25 to 49.9 were randomly assigned to 1 of 5 low-fat, low-glycemic index diets: vegan, vegetarian, pesco-vegetarian, semi-vegetarian or omnivorous, with 12 or 13 people in each group. The diets did not emphasize calorie restriction, and the omnivorous group had fewer group meetings in the first 2 months. Fifty people (79 percent) had their weight measured at 6 months, including 10 of 13 in the pesco-vegetarian group and 8 of 12 in the omnivorous group. At 6 months, weight had changed by -3.2 percent (standard deviation 3.4) in the pesco-vegetarian group and -3.1 percent (3.6) in the omnivorous group, against -7.5 percent (4.5) in the vegan group, which differed significantly from the pesco-vegetarian group (Turner-McGrievy et al., 2015).

Missing 6-month weights were filled in by assuming a gain of 0.3 kilograms a month; carrying the starting weight forward gave similar results. Participants and staff knew the assignments. The planned comparisons set the vegan group against the others, so the trial reports no estimate for pesco-vegetarian against omnivorous, and the near-equal averages do not show that the 2 diets have the same effect. The archive reports weight as something a study measured, not as a goal or a measure of whether a diet worked.

Mood

A 2-week pilot trial assigned 39 adults who ate meat daily to a diet without meat or poultry that included seafood at least 3 to 4 times a week, an omnivorous diet, or a lacto-vegetarian diet. It found no statistically clear improvement in the fish group's mood scores. With 13 people assigned to each group, unblinded self-report, a short duration and multiple mood measures, it cannot establish long-term mental-health effects (Beezhold & Johnston, 2012).

Against exercise or medication in older adults

A separate trial, CEV-65, enrolled 100 adults aged 65 or older with type 2 diabetes. Its "vegeterranean" dietary instructions recommended avoiding meat and poultry while allowing fish, eggs and dairy. It compared the diet with resistance exercise or empagliflozin, rather than another diet. A 10-week report analyzing 67 participants found no statistically clear difference between groups in resting metabolic rate (Buch et al., 2025). A later secondary report found no statistically clear between-group differences in changes in HbA1c or frailty scores (Gonen et al., 2026). These short-term analyses do not establish equivalent effects or justify replacing prescribed treatment.

Mortality

None of these trials was designed to test effects on death, and this page's searches did not identify a trial of a pescatarian diet that did.

Evidence from long-term prospective cohort studies

A cohort study follows people who already eat a certain way and records what happens to them. It can show that a pattern goes with an outcome; it cannot by itself show that the pattern caused it. The main cohorts with large numbers of fish eaters are the Adventist Health Study-2 in the United States and Canada, recruited from 2002 to 2007; EPIC-Oxford in the United Kingdom, recruited from 1993 to 2001 partly through vegetarian societies and magazines; the earlier Oxford Vegetarian Study; UK Biobank; and the UK Women's Cohort Study (Orlich et al., 2013; Tong et al., 2019; Scarborough et al., 2023; Dunneram et al., 2026).

Diet was measured by questionnaire, usually once at the start, and in most of these studies fish eaters were a small share of the people followed. People who choose this diet also tend to differ in other ways, such as smoking less, which the studies adjusted for as well as they could.

Cardiometabolic outcomes

In EPIC-Oxford, 48,188 people without heart disease or stroke were followed for 18.1 years on average. After adjusting for sociodemographic and lifestyle factors, the 7,506 fish eaters had a 13 percent lower rate of ischemic heart disease than meat eaters (hazard ratio 0.87, 95% confidence interval 0.77 to 0.99). For a person of the cohort's average age of 44.7, the study estimated 40.4 cases per 1,000 people over 10 years among fish eaters against 46.2 among meat eaters, a difference of 5.8 fewer cases (1.0 to 10.0 fewer), without accounting for competing causes of death (Tong et al., 2019).

In UK Biobank, 422,791 middle-aged adults were followed for a median of 8.5 years, and 9,951 (2.4 percent) were classified as fish eaters, people who ate fish, cheese and milk but no poultry or red meat. After adjusting for health conditions, lifestyle and body mass index, fish eaters had lower rates than meat-eaters of ischemic heart disease (hazard ratio 0.79, 0.70 to 0.88), heart attack (0.70, 0.56 to 0.88), heart failure (0.78, 0.63 to 0.97) and cardiovascular disease overall (0.93, 0.88 to 0.97) (Petermann-Rocha et al., 2021).

For stroke the 2 cohorts differ. In UK Biobank fish eaters had a lower stroke rate (hazard ratio 0.79, 0.63 to 0.98) (Petermann-Rocha et al., 2021). In EPIC-Oxford their total stroke rate was not clearly different from meat eaters', an estimated 17.5 against 15.4 cases per 1,000 over 10 years, a difference of 2.1 more cases (0.6 fewer to 5.3 more) (Tong et al., 2019).

Deaths from heart disease also differ between cohorts. In the Adventist Health Study-2, pesco-vegetarians had a lower rate of death from ischemic heart disease than nonvegetarians over about 6 years (hazard ratio 0.65, 0.43 to 0.97) (Orlich et al., 2013). In a combined analysis of EPIC-Oxford and the Oxford Vegetarian Study, fish eaters' rate of death from ischemic heart disease was not clearly different from regular meat eaters' (1.00, 0.75 to 1.34), and their rate of death from all circulatory diseases was higher (1.22, 1.02 to 1.46) (Appleby et al., 2016). In UK Biobank, fish eaters' lower rates of death from cardiovascular and ischemic heart disease in the simplest model disappeared after further adjustment (Petermann-Rocha et al., 2021).

For risk factors, the data are cross-sectional. In EPIC-Oxford, fish eaters reported high blood pressure less often than meat eaters, a difference the authors attributed largely to body mass index (Appleby et al., 2002). Among the fish eaters whose blood was measured, total cholesterol averaged 5.31 millimoles per liter against 5.50 in meat eaters (Tong et al., 2019). In the Adventist Health Study-2, 4.8 percent of pesco-vegetarians reported type 2 diabetes against 7.6 percent of nonvegetarians, an adjusted odds ratio of 0.70 (0.61 to 0.80) at a single point in time (Tonstad et al., 2009). Over 2 years of follow-up, 1.29 percent of pesco-vegetarians and 2.12 percent of nonvegetarians reported new diabetes, and after adjustment the difference was not statistically clear (odds ratio 0.79, 0.58 to 1.09) (Tonstad et al., 2013).

Cancer

The largest analysis pooled individual data from 9 cohorts in the United Kingdom, the United States, Taiwan and India, including 42,910 pescatarians and 1,645,555 meat eaters followed for a median of 16 years. Compared with meat eaters, pescatarians had a lower rate of colorectal cancer (hazard ratio 0.85, 0.77 to 0.93, based on 445 cases among pescatarians), which remained statistically significant after correction for testing many cancer sites. The cohorts did not differ much from one another. The association held after excluding the first 4 years of follow-up (0.87, 0.78 to 0.96), and was similar but no longer statistically clear in people who had never smoked (0.89, 0.78 to 1.01) (Dunneram et al., 2026).

The same analysis found lower rates of breast cancer (0.93, 0.88 to 0.98) and kidney cancer (0.73, 0.58 to 0.93) among pescatarians, but these did not survive correction for multiple testing, and the breast cancer difference was statistically significant only in postmenopausal women and was no longer statistically clear after excluding the first 4 years. In the main analyses, rates of the other cancers studied did not differ clearly from meat eaters'. The authors caution that the cohorts were mostly in the United Kingdom and the United States, that diet was classified once, and that pescatarians in these studies may not have eaten much fish (Dunneram et al., 2026). In the British cohorts, fish eaters also had a lower rate of death from cancer than regular meat eaters (hazard ratio 0.82, 0.70 to 0.97) (Appleby et al., 2016).

Body weight, as measured

In cross-sectional data, fish eaters' average body mass index was lower than meat eaters' in EPIC-Oxford (Spencer et al., 2003), and averaged 26.3 in Adventist pesco-vegetarians against 28.8 in nonvegetarians (Tonstad et al., 2009). Over 5 years in EPIC-Oxford, average weight gain was about 400 grams a year overall, and slightly smaller in fish-eating women than in meat-eating women (Rosell et al., 2006). These are measurements reported by the studies, not goals.

Mortality

In the Adventist Health Study-2, 7,194 pesco-vegetarians had a lower death rate than nonvegetarians over about 6 years (hazard ratio 0.81, 0.69 to 0.94), with the association clearer in men than in women (Orlich et al., 2013). In an update of the same cohort, with 11 years of follow-up and 88,400 participants, the lower rate held after adjusting for existing disease, at 0.85 (0.76 to 0.95) at age 65 and 0.90 (0.86 to 0.99, as printed) at age 85 (Abris et al., 2024). The comparison group in these studies was other Adventists, who are generally health conscious.

Three other cohort analyses gave estimates near no difference or too imprecise to tell. In EPIC-Oxford and the Oxford Vegetarian Study combined, 8,516 fish eaters had a death rate not clearly different from that of regular meat eaters (hazard ratio 0.96, 0.86 to 1.06) (Appleby et al., 2016). In an American cancer screening cohort followed for 18 years, the 310 people who identified as pesco-vegetarians, 67 of whom died, had an estimate of 0.81 (0.64 to 1.03) compared with omnivores (Blackie et al., 2023). In the Australian 45 and Up Study, 1,122 pesco-vegetarians had 46 deaths over a mean of 6.1 years; the adjusted estimate was 0.79 (0.59 to 1.06) compared with regular meat eaters, so a lower rate was possible but not statistically clear (Mihrshahi et al., 2017).

Fractures

In EPIC-Oxford, 8,037 fish eaters followed for an average of 17.6 years had a higher rate of hip fracture than meat eaters after adjustment for body mass index (hazard ratio 1.26, 1.02 to 1.54), about 2.9 more cases per 1,000 people over 10 years (Tong et al., 2020). In the UK Women's Cohort Study, pescatarian women's hip fracture rate was not clearly different from regular meat eaters' (0.97, 0.75 to 1.26) over 22.3 years (Webster et al., 2022), and in UK Biobank it was not clearly different (1.08, 0.86 to 1.35) over 12.5 years (Webster et al., 2023).

Highlighted studies

These 4 studies carry the most weight for this diet.

On a narrow screen, scroll the table sideways to see every column.

Highlighted studies for the Pescatarian Diet

Study	Design	Sample size	Duration	Finding	The limitation that matters
Adventist Health Study-2 (Orlich et al., 2013; Abris et al., 2024)	Prospective cohort	73,308 in the first analysis, including 7,194 pesco-vegetarians; 88,400 in the update	About 6 years, then a median of 11 years	Pesco-vegetarians had a lower death rate than nonvegetarians: hazard ratio 0.81 (0.69 to 0.94), and 0.85 (0.76 to 0.95) at age 65 in the update	One religious community with a health-conscious comparison group; diet measured once; the British estimate was closer to no difference
EPIC-Oxford (Tong et al., 2019)	Prospective cohort	48,188, including 7,506 fish eaters	18.1 years on average	Fish eaters had a 13 percent lower rate of ischemic heart disease than meat eaters: hazard ratio 0.87 (0.77 to 0.99)	Volunteers recruited partly through vegetarian societies; the upper end of the interval is close to no difference
Cancer Risk in Vegetarians Consortium (Dunneram et al., 2026)	Pooled analysis of 9 prospective cohorts	1,817,477, including 42,910 pescatarians	Median of 16 years	Pescatarians had a lower rate of colorectal cancer than meat eaters: hazard ratio 0.85 (0.77 to 0.93)	Diet classified once; in never smokers the estimate was similar but no longer statistically clear
Dinu et al., 2025	Randomized trial, open-label, 3 groups	113 randomized, 103 finished	12 weeks	Some stool, iron and inflammation markers rose more on the meat-based diets than on the pesco-vegetarian diet; the main DNA-damage outcome did not differ clearly between diets	Laboratory markers only, not validated as stand-ins for cancer; only those who finished were analyzed

Head to head

Three trials compared a pescatarian diet directly with other diets; the 2-week mood trial is described above. In the South Carolina trial, the pesco-vegetarian group lost less weight over 6 months than the vegan group, and its average change was close to the omnivorous group's, although the trial reports no estimate of the difference between those 2 groups (Turner-McGrievy et al., 2015). Against a meat-based diet, the Florence trial found more favorable changes in several laboratory markers but no clear difference in its main outcome or in cholesterol (Dinu et al., 2025). The cohorts in this section also report vegetarians and vegans separately; those comparisons belong to the Vegetarian Diet and Vegan Diet pages. No trial identified in this page's searches compared a pescatarian diet with the Mediterranean Diet or the DASH Diet.

Where the evidence is absent

In searches of Europe PMC and PubMed run October 4, 2026, logged in this page's working files, this page did not identify a randomized trial of a pescatarian diet that measured heart attacks, strokes, cancer or death; the longest trial found lasted 6 months. It did not identify a trial in pregnancy, in children or adolescents, or in athletes; a study of why people stop the diet or of what happens after they stop; or a study that compared people eating mostly oily fish with people eating mostly lean fish or shellfish within this pattern. The cohorts rarely recorded how fish was cooked.

Most of the people studied lived in the United Kingdom or the United States, many in cohorts recruited because they were interested in vegetarian diets or belonged to one religious community. Two older meta-analyses pooled pesco-vegetarian results, one on death and one on colorectal and other cancers. This page does not use their pooled numbers: the older mortality synthesis predates additional cohort reports and the Adventist update, and the older cancer synthesis is superseded by the larger 2026 individual-participant analysis (Godos et al., 2017; Jafari et al., 2022).

5. Mechanisms

(optional reading; select the heading to open or close this section)

This section explains how the diet is thought to work in the body. You can skip it. Nothing in the coaching sections depends on it.

Established mechanisms

LDL cholesterol causes ischemic heart disease, which trials of cholesterol-lowering drugs and genetic studies have confirmed, so any diet that lowers it would be expected to lower heart disease to some degree (Tong et al., 2019). In EPIC-Oxford, fish eaters' total cholesterol was slightly lower than meat eaters', but the study did not show how much of their lower rate of heart disease this explains, and the Florence trial found no clear difference in LDL cholesterol between a pesco-vegetarian and a meat-based diet over 12 weeks (Tong et al., 2019; Dinu et al., 2025).

Proposed mechanisms

The American Heart Association suggests that the link between fish-containing diets and fewer cardiovascular events may be due to the omega-3 fats in fish and seafood, to fish replacing other animal protein that is high in saturated fat, or to both (Lichtenstein et al., 2026). For colorectal cancer, one proposal is that leaving out red meat reduces exposure to heme iron, which promotes fat oxidation in the gut; the Florence trial's marker results fit that idea but do not show an effect on cancer (Dinu et al., 2025).

A small crossover study, read in its abstract, gave 30 healthy adults a combination of fermentable fiber and fish oil, or a comparison of maltodextrin and corn oil, for 30 days each, and its authors propose that the combination promotes a form of cell death in colon cells (Fan et al., 2026). That study tested supplements, not a diet. These proposed mechanisms explain why the associations in section 4 are plausible; they do not support any claim there.

6. Risks, contraindications and myths

(select the heading to open or close this section)

Warnings from professional or regulatory bodies

The FDA and EPA advice on eating fish, which treats fish and shellfish together as fish, states: "While it is important to limit mercury in the diets of those who are pregnant or breastfeeding and children, many types of fish are both nutritious and lower in mercury." It sorts fish into "Best Choices," "Good Choices," and "Choices to Avoid," and for fish caught by family or friends advises checking local fish and shellfish advisories and, where there is no advisory, eating "only one serving and no other fish that week" (U.S. Food and Drug Administration, n.d.).

On supplements, the American Heart Association states that "fish oil supplementation alone has not been demonstrated to lower CVD risk in otherwise healthy adults and in some people may be associated with an increased risk of atrial fibrillation" (Lichtenstein et al., 2026).

Nutrient gaps

Fish, and eggs or dairy foods when included, provide additional potential sources of several nutrients. Whether the diet meets a person's needs depends on the foods and amounts eaten, including fortification. The Office of Dietary Supplements lists fish among the food sources of vitamin B12, names seafood, eggs and dairy foods among the best sources of iodine, names seafood among the richest sources of heme iron, and names fatty fish among the best food sources of vitamin D (Office of Dietary Supplements, n.d.-a, n.d.-b, n.d.-d, n.d.-e). Seafood also helps the body absorb iron from plant foods (Office of Dietary Supplements, n.d.-b).

The amounts depend on what a person eats. The long-chain omega-3 fats EPA and DHA are high in cold-water fatty fish such as salmon, mackerel, herring and sardines, and lower in lean fish such as cod and tilapia and in shellfish (Office of Dietary Supplements, n.d.-c). Iodine can also run low: in a Norwegian study of 205 adults, including 35 pescatarians, median urinary iodine was below World Health Organization thresholds in every diet group (Henjum et al., 2023). A pescatarian who eats little fish, or no eggs or dairy foods, faces more of the gaps described on the Vegan Diet page, and supplement decisions go to a physician or registered dietitian.

Who should not follow it without medical supervision

People who are pregnant, may become pregnant or are breastfeeding, and parents feeding young children, need fish choices that limit mercury, and their care team and a registered dietitian plan them (U.S. Food and Drug Administration, n.d.). People with kidney disease need an eating plan that depends on the stage of their disease, their lab results and whether they are on dialysis, which their kidney care team sets. People with a current or past eating disorder consider any diet that removes foods with their treatment team.

Medication interactions

No interaction between eating fish and common medications was identified in the sources opened for this page. Fish oil supplements are the exception to watch: at high doses fish oil can have antiplatelet effects and might prolong clotting times with warfarin, although most research has not found a significant effect at 3 to 6 grams a day, and the prescribing information for omega-3 medicines advises periodic monitoring of clotting tests when they are taken with anticoagulants (Office of Dietary Supplements, n.d.-c). A coach never adjusts medication or supplements; a client on warfarin, insulin, sulfonylureas or blood pressure medication who plans a substantial change in eating keeps the prescriber informed before the change.

Signs it is going wrong

A coach or family member might notice ongoing tiredness or weakness, weight loss the person did not intend, meals that have narrowed to a few foods, distress or guilt around eating, or withdrawal from meals with others. None of these is a diagnosis. Persistent physical symptoms and unintended weight loss call for clinical follow-up. For changes in food rules or social eating, the coach explores purpose, distress, narrowing and interference with daily life; a real concern follows their own referral process or the client's existing care plan.

Myths and where they came from

Myth: "Any diet with fish in it is heart healthy."

Where it came from: the pattern is defined by what it leaves out, and the research groups people by the foods they avoid rather than the foods they eat, so fish eaters in the cohorts may not have eaten much fish (Dunneram et al., 2026). What is true: the American Heart Association rates the pescetarian pattern highly only when it is implemented as intended, and says it is not inherently health promoting if made up mostly of fried fish or refined grains, sweets and tropical oils (Gardner et al., 2023).

Myth: "Fish oil capsules do the same thing as eating fish."

Where it came from: cohort studies link dietary patterns containing nonfried fish with fewer cardiovascular events. What is true: the American Heart Association states that fish oil supplementation alone has not been shown to lower cardiovascular risk in otherwise healthy adults, and may be associated with atrial fibrillation in some people (Lichtenstein et al., 2026).

Myth: "If you are pregnant, you should stop eating fish."

Where it came from: concern about mercury, which the federal advice addresses by sorting fish into lists. What is true: the FDA and EPA advise 2 to 3 servings a week from the "Best Choices" list in pregnancy and breastfeeding, and avoiding the 7 fish with the highest mercury levels (U.S. Food and Drug Administration, n.d.). The details for any one person go to the prenatal care team.

7. Key terms

Pescatarian

A person whose diet includes fish but no other meat; also spelled pescetarian.

Pesco-vegetarian

A research term for a person who eats fish but no meat or poultry, usually along with eggs and dairy foods.

Fish eater

The term some British cohorts use for people who eat fish but no meat.

Ischemic heart disease

Heart disease caused by narrowed arteries that reduce blood flow to the heart muscle, including heart attacks.

Prospective cohort study

A study that records what people eat and then follows them over time to see what happens to their health.

Hazard ratio

A comparison of how often an outcome happens over time in one group against another; a value below 1 means it happened less often in the first group.

Pooled analysis

A study that combines the individual records of people from several cohorts and analyzes them together.

Life-cycle assessment

A method that estimates the environmental impact of a food from production to sale.

Methylmercury

A toxic form of mercury that builds up in fish and other seafood in varying amounts, which is why federal advice sorts fish by mercury level.

Long-chain omega-3 fats

EPA and DHA, fats found mainly in fish and seafood, which the body makes only in small amounts from the plant omega-3 fat ALA.

8. Review questions

1. What does a pescatarian diet leave out, and how do the definitions used in the Adventist Health Study-2, EPIC-Oxford and the pooled cancer analysis differ? Why does that matter when comparing their results?
2. In EPIC-Oxford and UK Biobank, who was compared with whom, for how long, and what was found for ischemic heart disease? Why do these studies not show that eating fish instead of meat prevents heart disease? (This question draws on section 4.)
3. A client who is 10 weeks pregnant tells you she has been eating swordfish and tuna steaks several times a week since giving up meat. What can you share with her permission, what do you ask, and where is the referral line?
4. A client says fish oil capsules will give him the same heart benefit as eating fish. Where does that belief come from, and what does the American Heart Association say? (This question draws on section 6.)

9. References

Abris, G. P., Shavlik, D. J., Mathew, R. O., Butler, F. M., Oh, J., Sirirat, R., Sveen, L. E., & Fraser, G. E. (2024). Cause-specific and all-cause mortalities in vegetarian compared with those in nonvegetarian participants from the Adventist Health Study-2 cohort. American Journal of Clinical Nutrition, 120(4), 907-917. https://doi.org/10.1016/j.ajcnut.2024.07.028

Appleby, P. N., Davey, G. K., & Key, T. J. (2002). Hypertension and blood pressure among meat eaters, fish eaters, vegetarians and vegans in EPIC-Oxford. Public Health Nutrition, 5(5), 645-654. https://doi.org/10.1079/PHN2002332

Appleby, P. N., Crowe, F. L., Bradbury, K. E., Travis, R. C., & Key, T. J. (2016). Mortality in vegetarians and comparable nonvegetarians in the United Kingdom. American Journal of Clinical Nutrition, 103(1), 218-230. https://doi.org/10.3945/ajcn.115.119461

Beezhold, B. L., & Johnston, C. S. (2012). Restriction of meat, fish, and poultry in omnivores improves mood: A pilot randomized controlled trial. Nutrition Journal, 11, Article 9. https://doi.org/10.1186/1475-2891-11-9

Blackie, K., Bobe, G., & Takata, Y. (2023). Vegetarian diets and risk of all-cause mortality in a population-based prospective study in the United States. Journal of Health, Population and Nutrition, 42(1), Article 130. https://doi.org/10.1186/s41043-023-00460-9

Buch, A., Eldor, R., Kis, O., Ben-Yehuda, A., Green, G., Greenman, Y., & Barak, S. (2025). Metabolic and functional factors associated with a change in resting metabolic rate among older adults with type 2 diabetes: Results from the CEV-65 randomized trial. Heliyon, 11(2), Article e41593. https://doi.org/10.1016/j.heliyon.2024.e41593

Chouraqui, J. P. (2023). Vegetarian diets and diets which restrict animal-source foods during childhood in high-income countries. Paediatrics and International Child Health, 43(4), 57-82. https://doi.org/10.1080/20469047.2023.2245186

Dinu, M., Ristori, S., Pagliai, G., Lotti, S., Meriggi, N., Nerini, A., Chevolleau, S., Bowman, J., Caderni, G., Colombini, B., Gerard, P., Giovannelli, L., Gueraud, F., Marcucci, R., Pierre, F., De Filippo, C., & Sofi, F. (2025). Effects of meat-based, meat-based with α-tocopherol, and pesco-vegetarian diets on biomarkers associated with colorectal cancer risk: A randomized behavioral intervention trial. Scientific Reports, 16, Article 1502. https://doi.org/10.1038/s41598-025-31410-6

Dunneram, Y., Lee, J. Y., Watling, C. Z., Lawson, I., Parsaeian, M., Fraser, G. E., Butler, F. M., Prabhakaran, D., Shridhar, K., Kondal, D., Mohan, V., Ali, M. K., Narayan, K. M. V., Tandon, N., Tong, T. Y. N., Travis, R. C., Chiu, T. H. T., Lin, M. N., Lin, C. L., . . . Perez-Cornago, A. (2026). Vegetarian diets and cancer risk: Pooled analysis of 1.8 million women and men in nine prospective studies on three continents. British Journal of Cancer, 134(8), 1218-1229. https://doi.org/10.1038/s41416-025-03327-4

Fan, Y. Y., Salinas, M. L., Mullens, D. A., Davidson, L. A., Goldsby, J. S., Ivanov, I. V., Jayaraman, A., Cai, J. J., Levy, L., Hullar, M. A., Navarro, S. L., Lampe, J. W., & Chapkin, R. S. (2026). Pesco-vegetarian food components promote colonocyte ferroptosis in preclinical mouse models and a randomized crossover trial in healthy human adults. Journal of Nutrition, 156(2), Article 101287. https://doi.org/10.1016/j.tjnut.2025.101287

Food and Agriculture Organization of the United Nations. (2024). The status of fishery resources. In The state of world fisheries and aquaculture 2024. https://doi.org/10.4060/cd0683en

Forestell, C. A., Spaeth, A. M., & Kane, S. A. (2012). To eat or not to eat red meat. A closer look at the relationship between restrained eating and vegetarianism in college females. Appetite, 58(1), 319-325. https://doi.org/10.1016/j.appet.2011.10.015

Gardner, C. D., Vadiveloo, M. K., Petersen, K. S., Anderson, C. A. M., Springfield, S., Van Horn, L., Khera, A., Lamendola, C., Mayo, S. M., & Joseph, J. J. (2023). Popular dietary patterns: Alignment with American Heart Association 2021 dietary guidance: A scientific statement from the American Heart Association. Circulation, 147(22), 1715-1730. https://doi.org/10.1161/CIR.0000000000001146

Godos, J., Bella, F., Sciacca, S., Galvano, F., & Grosso, G. (2017). Vegetarianism and breast, colorectal and prostate cancer risk: An overview and meta-analysis of cohort studies. Journal of Human Nutrition and Dietetics, 30(3), 349-359. https://doi.org/10.1111/jhn.12426

Gonen, L. D., Buch, A., Eldor, R., Yaish, I., & Barak, S. (2026). Clinical similarity, economic divergence: Cost-effectiveness and population health implications of dietary, pharmacological, and exercise interventions in older adults with type 2 diabetes: A secondary analysis of a randomized controlled trial. BMC Geriatrics. Advance online publication of the accepted manuscript. https://doi.org/10.1186/s12877-026-07994-7

Groufh-Jacobsen, S., Larsson, C., Margerison, C., Mulkerrins, I., Aune, D., & Medin, A. C. (2024). Micronutrient intake and status in young vegans, lacto-ovo-vegetarians, pescatarians, flexitarians, and omnivores. European Journal of Nutrition, 63(7), 2725-2741. https://doi.org/10.1007/s00394-024-03453-4

Henjum, S., Groufh-Jacobsen, S., Aakre, I., Gjengedal, E. L. F., Langfjord, M. M., Heen, E., Sele, V., & Andersson, M. (2023). Thyroid function and urinary concentrations of iodine, selenium, and arsenic in vegans, lacto-ovo vegetarians and pescatarians. European Journal of Nutrition, 62(8), 3329-3338. https://doi.org/10.1007/s00394-023-03218-5

Jafari, S., Hezaveh, E., Jalilpiran, Y., Jayedi, A., Wong, A., Safaiyan, A., & Barzegar, A. (2022). Plant-based diets and risk of disease mortality: A systematic review and meta-analysis of cohort studies. Critical Reviews in Food Science and Nutrition, 62(28), 7760-7772. https://doi.org/10.1080/10408398.2021.1918628

Lichtenstein, A. H., Khera, A., Anderson, C. A. M., Appel, L. J., DeSilva, D. M., Gardner, C., Hu, F. B., Jones, D. W., Petersen, K. S., & American Heart Association. (2026). 2026 dietary guidance to improve cardiovascular health: A scientific statement from the American Heart Association. Circulation, 153(18), e1285-e1295. https://doi.org/10.1161/CIR.0000000000001435

Lombardo, M., Feraco, A., Camajani, E., Gorini, S., Strollo, R., Armani, A., Padua, E., & Caprio, M. (2024). Effects of different nutritional patterns and physical activity on body composition: A gender and age group comparative study. Foods, 13(4), Article 529. https://doi.org/10.3390/foods13040529

Merriam-Webster. (n.d.). Pescatarian. In Merriam-Webster.com dictionary. merriam-webster.com/dictionary/pescatarian

Mihrshahi, S., Ding, D., Gale, J., Allman-Farinelli, M., Banks, E., & Bauman, A. E. (2017). Vegetarian diet and all-cause mortality: Evidence from a large population-based Australian cohort - the 45 and Up Study. Preventive Medicine, 97, 1-7. https://doi.org/10.1016/j.ypmed.2016.12.044

Moore, W. J., McGrievy, M. E., & Turner-McGrievy, G. M. (2015). Dietary adherence and acceptability of five different diets, including vegan and vegetarian diets, for weight loss: The New DIETs study. Eating Behaviors, 19, 33-38. https://doi.org/10.1016/j.eatbeh.2015.06.011

Office of Dietary Supplements. (n.d.-a). Iodine: Fact sheet for health professionals. National Institutes of Health. ods.od.nih.gov/factsheets/Iodine-HealthProfessional

Office of Dietary Supplements. (n.d.-b). Iron: Fact sheet for health professionals. National Institutes of Health. ods.od.nih.gov/factsheets/Iron-HealthProfessional

Office of Dietary Supplements. (n.d.-c). Omega-3 fatty acids: Fact sheet for health professionals. National Institutes of Health. ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional

Office of Dietary Supplements. (n.d.-d). Vitamin B12: Fact sheet for health professionals. National Institutes of Health. ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional

Office of Dietary Supplements. (n.d.-e). Vitamin D: Fact sheet for health professionals. National Institutes of Health. ods.od.nih.gov/factsheets/VitaminD-HealthProfessional

Orlich, M. J., Singh, P. N., Sabaté, J., Jaceldo-Siegl, K., Fan, J., Knutsen, S., Beeson, W. L., & Fraser, G. E. (2013). Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Internal Medicine, 173(13), 1230-1238. https://doi.org/10.1001/jamainternmed.2013.6473

Petermann-Rocha, F., Parra-Soto, S., Gray, S., Anderson, J., Welsh, P., Gill, J., Sattar, N., Ho, F. K., Celis-Morales, C., & Pell, J. P. (2021). Vegetarians, fish, poultry, and meat-eaters: Who has higher risk of cardiovascular disease incidence and mortality? A prospective study from UK Biobank. European Heart Journal, 42(12), 1136-1143. https://doi.org/10.1093/eurheartj/ehaa939

Rosell, M., Appleby, P., Spencer, E., & Key, T. (2006). Weight gain over 5 years in 21,966 meat-eating, fish-eating, vegetarian, and vegan men and women in EPIC-Oxford. International Journal of Obesity, 30(9), 1389-1396. https://doi.org/10.1038/sj.ijo.0803305

Scarborough, P., Clark, M., Cobiac, L., Papier, K., Knuppel, A., Lynch, J., Harrington, R., Key, T., & Springmann, M. (2023). Vegans, vegetarians, fish-eaters and meat-eaters in the UK show discrepant environmental impacts. Nature Food, 4(7), 565-574. https://doi.org/10.1038/s43016-023-00795-w

Spencer, E. A., Appleby, P. N., Davey, G. K., & Key, T. J. (2003). Diet and body mass index in 38000 EPIC-Oxford meat-eaters, fish-eaters, vegetarians and vegans. International Journal of Obesity and Related Metabolic Disorders, 27(6), 728-734. https://doi.org/10.1038/sj.ijo.0802300

Springmann, M., Clark, M. A., Rayner, M., Scarborough, P., & Webb, P. (2021). The global and regional costs of healthy and sustainable dietary patterns: A modelling study. Lancet Planetary Health, 5(11), e797-e807. https://doi.org/10.1016/S2542-5196(21)00251-5

Tong, T. Y. N., Appleby, P. N., Bradbury, K. E., Perez-Cornago, A., Travis, R. C., Clarke, R., & Key, T. J. (2019). Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: Results from the prospective EPIC-Oxford study. BMJ, 366, Article l4897. https://doi.org/10.1136/bmj.l4897

Tong, T. Y. N., Appleby, P. N., Armstrong, M. E. G., Fensom, G. K., Knuppel, A., Papier, K., Perez-Cornago, A., Travis, R. C., & Key, T. J. (2020). Vegetarian and vegan diets and risks of total and site-specific fractures: Results from the prospective EPIC-Oxford study. BMC Medicine, 18, Article 353. https://doi.org/10.1186/s12916-020-01815-3

Tonstad, S., Butler, T., Yan, R., & Fraser, G. E. (2009). Type of vegetarian diet, body weight, and prevalence of type 2 diabetes. Diabetes Care, 32(5), 791-796. https://doi.org/10.2337/dc08-1886

Tonstad, S., Stewart, K., Oda, K., Batech, M., Herring, R. P., & Fraser, G. E. (2013). Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutrition, Metabolism and Cardiovascular Diseases, 23(4), 292-299. https://doi.org/10.1016/j.numecd.2011.07.004

Turner-McGrievy, G. M., Davidson, C. R., Wingard, E. E., Wilcox, S., & Frongillo, E. A. (2015). Comparative effectiveness of plant-based diets for weight loss: A randomized controlled trial of five different diets. Nutrition, 31(2), 350-358. https://doi.org/10.1016/j.nut.2014.09.002

U.S. Food and Drug Administration. (n.d.). Advice about eating fish. fda.gov/food/consumers/advice-about-eating-fish

Webster, J., Greenwood, D. C., & Cade, J. E. (2022). Risk of hip fracture in meat-eaters, pescatarians, and vegetarians: Results from the UK Women's Cohort Study. BMC Medicine, 20, Article 275. https://doi.org/10.1186/s12916-022-02468-0

Webster, J., Greenwood, D. C., & Cade, J. E. (2023). Risk of hip fracture in meat-eaters, pescatarians, and vegetarians: A prospective cohort study of 413,914 UK Biobank participants. BMC Medicine, 21, Article 278. https://doi.org/10.1186/s12916-023-02993-6

Evidence rating and review record

Each row identifies the method, source, outcome or recommendation, and comparison being rated. Ratings from different tools are not interchangeable. The source is either a named published review or this page's own judgment. The rating in the banner is for lower rates of ischemic heart disease, and the banner names the tool that produced it. A high rating means the research is solid; it does not mean the diet is right for everyone, and it does not mean a coach should recommend it.

Every rating on this page uses GRADE, the same 4-level scale used in the clinical guidelines you will meet in practice. High means further research is very unlikely to change the conclusion. Moderate means further research may change it. Low means further research is likely to change it. Very low means the conclusion is uncertain. GRADE rates each outcome separately, so a diet can be low for one outcome and very low for another.

The 6 ratings below are this page's own assessments, assigned from the evidence under the archive's September 28, 2026 decision; no published GRADE rating of a pescatarian diet was found in the sources opened for this page. Cohort evidence starts at low and randomized trials start at high, and each row's reasons say which concerns lowered it. Stroke, cancers other than colorectal cancer, deaths from heart disease, the laboratory markers in the Florence trial, the mood scores in the 2-week trial and the CEV-65 results for resting metabolism, HbA1c and frailty are described in section 4 but not rated. The cohort ratings describe associations in people who already ate this way, not the effect of switching to the diet.

On a narrow screen, scroll the table sideways to see every column.

Evidence ratings, their sources and reasons

Outcome	Certainty	Who rated it, and for which comparison	Why it is rated this way
Ischemic heart disease (the banner rating)	Low	This page's own judgment, using the GRADE approach, from Tong et al. (2019) and Petermann-Rocha et al. (2021). Comparison: adults who ate fish but no meat against meat eaters, in 2 UK cohorts, over 18.1 years on average and a median of 8.5 years; hazard ratios 0.87 (0.77 to 0.99) and 0.79 (0.70 to 0.88).	Observational studies start at low. Not lowered for risk of bias: both cohorts adjusted for the main known confounders, and UK Biobank also for existing conditions and body mass index; diet measured at the start and residual confounding are the reasons observational evidence starts low and are not counted again. Not lowered for inconsistency: both estimates point the same way and their intervals overlap. Not lowered for indirectness: the populations and comparison match the question, although EPIC-Oxford volunteers were unusually health conscious. Not lowered for imprecision: the UK Biobank interval excludes no difference, although the EPIC-Oxford interval reaches close to it. Publication bias was not assessed: 2 cohorts are too few to judge. Not raised: the associations are modest, below the size GRADE uses to raise a rating. That gives low.
Death from any cause	Low	This page's own judgment, using the GRADE approach, from Orlich et al. (2013), Abris et al. (2024), Appleby et al. (2016), Blackie et al. (2023) and Mihrshahi et al. (2017). Comparison: pesco-vegetarians or fish eaters against nonvegetarians, regular meat eaters or omnivores, from 5 named cohorts in 4 study populations, with the 2 partly overlapping British cohorts analyzed together and the Adventist update counted once, followed for about 6 to 18 years; hazard ratios 0.81 (0.69 to 0.94), and 0.85 (0.76 to 0.95) at age 65 in the update, in the Adventist cohort; 0.96 (0.86 to 1.06) in the 2 British cohorts combined; 0.81 (0.64 to 1.03) in the American screening cohort; 0.79 (0.59 to 1.06) in the Australian cohort.	Observational studies start at low. Not lowered for risk of bias: each study adjusted for the main known confounders, including smoking. Not lowered for inconsistency: all 4 estimates point toward a lower death rate and their intervals overlap; different significance labels do not show that the results disagree, although the differing comparison groups, from health-conscious Adventists to regular meat eaters, warrant caution. Not lowered for indirectness: the populations and comparisons match the question. Not lowered for imprecision: the rating is for a lower rate of uncertain, probably modest size; the Adventist interval excludes no difference, and the British interval excludes both a 25 percent reduction, the threshold used on this page, and an increase of more than 6 percent. Publication bias could not be assessed with 4 sets of analyses. Not raised: the associations are modest. That gives low.
Colorectal cancer	Low	This page's own judgment, using the GRADE approach, from Dunneram et al. (2026), a pooled analysis of individual data that published no GRADE rating. Comparison: pescatarians against meat eaters in 9 cohorts, median follow-up of 16 years; hazard ratio 0.85 (0.77 to 0.93), 445 cases among pescatarians.	Observational studies start at low. Not lowered for risk of bias: the analysis used the same definitions and adjustment for major non-dietary risk factors, including detailed smoking history, in every cohort, and the association held after excluding the first 4 years (0.87, 0.78 to 0.96); in never smokers the estimate was similar (0.89) but the interval, from fewer cases, included no difference, so some residual confounding by smoking cannot be ruled out. Not lowered for inconsistency: heterogeneity between cohorts was low (17.4 percent). Not lowered for indirectness: most participants lived in the United Kingdom or the United States. Not lowered for imprecision: the interval excludes no difference and survived correction for multiple testing. Publication bias was not suspected: the consortium set out to include every identified cohort. Not raised: the association is modest. That gives low.
New type 2 diabetes	Very low	This page's own judgment, using the GRADE approach, from Tonstad et al. (2013). Comparison: pesco-vegetarians against nonvegetarians in the Adventist Health Study-2, over 2 years; odds ratio 0.79 (0.58 to 1.09).	Observational studies start at low. Lowered 1 level for imprecision: the interval runs from 42 percent lower odds to 9 percent higher, so it includes both a meaningful benefit and no difference, from a single cohort. That gives very low. Not lowered for risk of bias: diabetes was self-reported on a questionnaire after 2 years and diet was measured once, but the authors confirmed 97.4 percent of the self-reports they checked; nonresponse to the follow-up questionnaire is a limitation. Not lowered for indirectness: the outcome and comparison match the question, although the results may not apply beyond Adventists. The cross-sectional prevalence result (Tonstad et al., 2009) was not used, because it cannot show which came first. Inconsistency and publication bias cannot be judged from one cohort.
Hip fracture	Very low	This page's own judgment, using the GRADE approach, from Tong et al. (2020), Webster et al. (2022) and Webster et al. (2023). Comparison: fish eaters or pescatarians against meat eaters or regular meat eaters, in 3 UK cohorts followed for 12.5 to 22.3 years; hazard ratios 1.26 (1.02 to 1.54), 0.97 (0.75 to 1.26) and 1.08 (0.86 to 1.35).	Observational studies start at low. Lowered 1 level for serious imprecision: the individual cohort intervals allow little or no difference and increases of at least 25 percent in risk, the threshold used on this page. Not lowered for inconsistency: the point estimates differ, but their overlapping intervals do not by themselves establish serious inconsistency. Not lowered for risk of bias: each cohort adjusted for body mass index and lifestyle factors, although residual confounding remains a limitation. Not lowered for indirectness: UK adults and the rated comparison, although the UK Women's Cohort Study included only women and applicability beyond these UK cohorts is limited. Publication bias could not be assessed with 3 cohorts. That gives very low. Whether a pescatarian diet changes hip fracture risk, in either direction, is uncertain.
Body weight, as measured, at 6 months	Very low	This page's own judgment, using the GRADE approach, from Turner-McGrievy et al. (2015), read in full; the trial came with no published quality rating. Comparison: a low-fat, low-glycemic index pesco-vegetarian diet against an omnivorous diet, in adults with a body mass index of 25 to 49.9 in South Carolina, 13 and 12 randomized and analyzed, 10 and 8 with a measured 6-month weight; weight change -3.2 percent (standard deviation 3.4) against -3.1 percent (3.6) at 6 months.	Randomized trials start at high. Lowered 1 level for risk of bias: the omnivorous group had fewer group meetings in the first 2 months, participants and staff knew the assignments, allocation concealment was not described, and 3 of 13 and 4 of 12 weights were missing and filled in by assumption, although a second method gave similar results. Lowered 2 levels for very serious imprecision: the trial reports no estimate for this pair; an approximate interval this page calculated from the published averages, standard deviations and group sizes, not a published result, runs from about 3.0 percentage points more weight lost to 2.8 points less on the pesco-vegetarian diet. That includes differences 3 times this page's 1-point threshold in both directions. The threshold borrows the step between neighboring diets in the trial's 2-month power calculation; it was not an established clinical threshold for this 6-month comparison. Not lowered for indirectness: the row rates this program in these adults. Inconsistency and publication bias cannot be judged from one trial. Three levels down from high gives very low. This archive reports weight as a measurement, not as a goal.

How this archive talks about weight. This page reports what studies measured, including body weight, and does not treat weight change as a goal or as a measure of a diet's success. Weight a person loses without meaning to can be a sign of a health problem, and where it is, the page names it as a reason to see a clinician. People are described the way the study described them.

Last reviewed: Reviewed and approved by James Peth, MS, MPH, PhD, on October 6, 2026, after a combined final review of the third batch of 5 archive pages, the plant-based family, the repairs it asked for, a focused recheck and a repair confirmation. Written October 4, 2026. All 6 ratings are this page's own judgment from the evidence.

Updated October 21, 2026: The American Heart Association is now named as an author of its 2026 dietary guidance statement (Lichtenstein et al., 2026), as the publisher's citation credits it. No content changed.

Next scheduled review: August 2027. Pages built on annual guidance are rechecked each year. The federal advice on eating fish and the federal fact sheets cited on this page are updated from time to time and should be rechecked first.

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Diet Reference Archive | One James

Prepared by James Peth, MS, MPH, PhD

© 2026–2027 One James. All rights reserved.

This page is for education and coaching practice. It is not medical or dietary advice.