Neal Barnard

What Neal says, topic by topic

Vitamin B12

In a 2024 Exam Room fact check Barnard said B12 is made neither by animals nor by plants but by bacteria, and that meat eaters get some only because of bacteria in the animal¹. He said modern hygiene has removed the B12 people once picked up from soil and bacteria, that many foods such as breakfast cereals are fortified, and that he encourages every vegan to take one as a form of insurance².

In the same session he said supplements are well absorbed even without stomach acid, and that low B12 also turns up in meat eaters over 50 and in people on metformin or acid blockers³. PCRM’s nutrition FAQ likewise names a daily supplement as the simple way to cover B12, more reliable than fortified foods⁴.

What all the experts say about vitamin B12

Vitamin D

In 2021 Barnard said 20 minutes to half an hour of sun on the face and arms can supply vitamin D, but that sunscreen or staying indoors blocks it, so a supplement makes sense⁵. He put the usual dose at about 2,000 IU a day and warned that 5,000 or more risks taking too much⁶.

He gave the same figure in 2023 and said 5,000 to 10,000 IU could be toxic⁷. He added that vitamin D helps the body absorb calcium, may lower cancer risk, and that new data then pointed to a lower risk of Alzheimer’s disease too⁸. In 2021 he said testing should be routine, since people cannot feel a deficiency⁹.

What all the experts say about vitamin D

Omega-3 fats

In 2024 Barnard called alpha linolenic acid the parent omega-3, rich in chia and flax and present in many plants, greens among them¹⁰. He said vegan EPA and DHA capsules, made from algae, are the same as fish oil without the smell, algae being where fish get them in the first place¹¹.

In 2022 he said green leafy vegetables carry little fat, but much of it is omega-3, and that flax, chia or supplements are also fine¹². He noted that fish oil supplements have been linked with higher prostate cancer risk in men, and said some people test their omega-3 level first and only supplement with vegan EPA and DHA if it is low¹³.

PCRM’s omega-3 page cites the EPIC study, in which vegan women had more long chain omega-3 in their blood than fish eaters¹⁴.

What all the experts say about omega-3 fats

Oil

In 2023 Barnard rated olive oil far better than butter, at roughly 14% saturated fat against about half, but still advised keeping oils low for their calories and their effect on insulin resistance¹⁵. He pointed out that olive oil is made by discarding the fiber of thousands of olives¹⁶, and called adding extra olive oil to a Mediterranean diet a mistake¹⁷.

In a 2024 talk with Chef AJ he said coconut and palm oil raise cholesterol and should be left out¹⁸, and that even canola oil can quickly cause insulin resistance, so oils have to be cut¹⁹.

What all the experts say about oil

Protein

In the 2024 fact check Barnard said a vegan diet gives plenty of protein: 2,000 calories of broccoli alone would supply three times the official amount, and lentils do the same²⁰. He called food combining an idea from the 1980s and 1990s that no longer holds, since all plants contain all the essential amino acids²¹.

In March 2024 he cited Harvard research in which people who swapped animal protein, dairy protein included, for plant protein had lower mortality²². In 2026 he noted that soy milk carries as much protein as cow’s milk, about 8 grams a serving²³.

What all the experts say about protein

Calcium, dairy and bones

In the 2024 fact check Barnard said cows get their calcium from plants and people can do the same with green vegetables, which many people on any diet neglect²⁴. He said broccoli, Brussels sprouts and kale give well absorbed calcium while spinach and chard do not, putting milk calcium at about 32% absorbed against 64% for Brussels sprouts²⁵.

Asked about bone density in 2023, he said dairy calcium is not needed and people are better off without it; greens, beans and tofu supply calcium²⁶. He added vitamin D, from sun or a supplement, and exercise that pulls on the bones²⁷.

PCRM’s calcium page cites a Harvard study of 78,000 women in which those drinking milk twice a day or more had more hip fractures²⁸. It also says sodium raises calcium loss through the kidneys²⁹.

What all the experts say about calcium, dairy and bones

Iodine

In 2020 Barnard said sea vegetables such as wakame and nori are rich in iodine, so people far from the sea may run low, and that iodized salt helps but sea salt, Himalayan salt and kosher salt are not iodized unless the label says so³⁰.

In 2023 he said iodized salt, introduced around 1925, ended deficiency in the US almost at once, but people now cutting sodium or using other salts miss it³¹. He said the iodine in milk comes from disinfectant on the cow’s udder and from supplements given to cows³², and pointed instead to kelp based supplements, putting the need at 150 micrograms a day³³. In 2025 he again named seaweed, such as the nori on sushi or the wakame in miso soup, as an easy source³⁴.

What all the experts say about iodine

Calorie density

In a 2021 episode on the topic Barnard defined calorie density as calories per unit of food and said carbohydrates carry 4 calories per gram against 9 for fats such as chicken fat³⁵. Fiber adds bulk with almost no calories and water adds none, so even turning vegetables into soup lowers the density further³⁶.

For weight, he said in the same episode, all fats are about equal, which is why he advises a vegan diet very low in oil, with oil free dressings³⁷. In 2024 he made the same point with cheese: about 70% fat, it does fill people up, but only after a large calorie load³⁸.

What all the experts say about calorie density

Nuts, seeds and avocado

In 2022 Barnard said avocado fat is healthier than animal fat but still has 9 calories per gram, and that nuts or oils are often what stalls weight loss³⁹. Chia and flax in the usual tablespoon portions are fine, he said, since even an ounce of chia holds only about 9 grams of fat⁴⁰.

In 2024 he said nuts have vitamin E and good fats, but shelled and salted nuts are easy to overeat⁴¹. People with excess body fat or insulin resistance should keep them to a minimum, while healthy, lean people might have about an ounce a day, used as a flavoring rather than a main food⁴².

What all the experts say about nuts, seeds and avocado

Soy

In the 2024 fact check Barnard said soy isoflavones do not cause breast growth in men; the usual cause is body fat, which turns testosterone into estrogen⁴³⁴⁴. He called soy optional but a health food that lowers cholesterol a little, and said women eating the most soy have about 30% less breast cancer, with a similar drop in prostate cancer for men⁴⁵⁴⁶.

Talking with Rip Esselstyn in 2024 he said that among women already treated for breast cancer, those with the highest soy intake are 25 to 30% less likely to see it return or to die of it⁴⁷. He said PCRM’s menopause study cut hot flashes by almost 90% with a vegan diet, very little oil and half a cup of mature soybeans a day, rather than edamame⁴⁸⁴⁹.

In 2026 he called the idea that soy causes cancer a myth, rated soy milk probably the best of the non-dairy milks and named coconut milk as the one to avoid⁵⁰.

What all the experts say about soy

Salt

Discussing blood pressure in 2023, Barnard said doctors often set a limit of about 2,000 milligrams of sodium a day⁵¹, and that lowering both salt and fat brings blood pressure down⁵². He noted that the vegan diet in his own trial against a Mediterranean diet was not salt restricted⁵³.

He said cheese holds more sodium than potato chips, while fruits and vegetables are low in sodium and high in potassium, which itself lowers blood pressure⁵⁴.

What all the experts say about salt

Sugar

In 2020 Barnard said sugar addiction is real: the taste of sugar releases opiates in the brain, which then release dopamine, a milder pull than drugs but enough to keep people hooked⁵⁵. He saw sugar mixed with fat, as in pie, cake or donuts, as the worst form⁵⁶.

In 2024 he said diabetes stems from fat building up in muscle cells, which keeps glucose out, so removing fat lets the sugar back in⁵⁷. He defended fruit the same year, citing a study in which people adding three apples a day lost weight⁵⁸.

What all the experts say about sugar

Starches

In the 2024 fact check Barnard recalled a 2005 PCRM study of 64 women after menopause⁵⁹. On the vegan diet they ate rice, potatoes, sweet potatoes and pasta, their carbohydrate intake rose, and they lost about a pound a week without regaining it over two years⁶⁰.

In 2024 he also said a large potato has more protein than a large egg⁶¹, and that potatoes are blamed for weight gain caused by butter, sour cream, cheese and bacon on top⁶².

What all the experts say about starches

Fasting

Asked about fasting in 2021, Barnard said its benefits are real, but that 5:2 schemes are not truly fasting and many people cannot sustain them⁶³. He was most impressed by longer water only fasts under medical supervision, such as at TrueNorth in California, especially for autoimmune conditions⁶⁴. He called such fasting dangerous without supervision and said food must be brought back gradually afterwards⁶⁵.

What all the experts say about fasting

Supplements

In his 2014 talk on Alzheimer’s disease Barnard cited Chicago data in which people with a low intake of vitamin E had at least double the risk of those with a high intake⁶⁶. He still wanted it from greens, fruits, nuts and seeds rather than capsules, arguing that a pill carries only the few forms a manufacturer could make, not the full natural mix⁶⁷.

In 2020 he told an expectant mother to keep taking prenatal vitamins, which supply B12, through breastfeeding as well⁶⁸. In 2023 he advised against buying fat burning capsules, saying high fiber plant foods already curb appetite, carry some calories out and raise the after meal burn⁶⁹.

What all the experts say about supplements

Iron

In a 2014 talk on Alzheimer’s disease Barnard said the body needs iron to make hemoglobin, but too much is toxic, and a Chicago study found brain function worse at both low and high hemoglobin⁷⁰. He said milk with a meal cuts iron absorption by about half, while diets heavy in meat give too much⁷¹. Beans and greens, he said, supply non heme iron, which the body absorbs more when low and less when high⁷². He also mentioned cast iron pans and copper pipes as hidden sources of the two metals⁷³.

His view was the same in 2024. He said the 1950s idea that more iron is better gave way to evidence linking excess iron to heart disease and possibly dementia⁷⁴, and that heme iron from meat is absorbed whether the body needs it or not⁷⁵.

What all the experts say about iron

Fish and eggs

In 2024 Barnard said salmon is sold as a diet food but gets about 40% of its calories from fat in Atlantic salmon and about half in Chinook, with no fiber at all⁷⁶.

On eggs he said in 2024 that a large egg brings a heavy load of cholesterol and some saturated fat with no fiber⁷⁷. The yolk holds the fat and cholesterol, he said, and the white is animal protein people do not need⁷⁸. In the same talk he cited Harvard data in which swapping meat, dairy, eggs or fish for plant protein went with lower mortality⁷⁹.

What all the experts say about fish and eggs

Fiber

In 2026 Barnard said fiber has between zero and two calories per gram, and that people on a high fiber vegan diet eat two to three hundred fewer calories a day without noticing⁸⁰. Citing a Tufts study, he said fiber also carries some calories out unabsorbed, perhaps a hundred a day⁸¹. A fiber supplement would do the same, he said, but he would rather people get fiber in the plants themselves⁸².

In 2024 he ranked beans as the top fiber source, followed by vegetables, fruits and whole grains, and noted that cheese, meat, eggs and refined foods have none⁸³.

What all the experts say about fiber

Fruit

In his 2024 talk with Chef AJ on the Power Foods book, Barnard said Harvard researchers tracking over 100,000 people found berries at the top of the foods linked with losing weight, citing their fiber, slowly absorbed sugars and anthocyanin pigments⁸⁴. Citrus came fourth, with juice counted too, followed by melons, which he praised for their fiber and water⁸⁵.

In March 2024 he described a trial in which volunteers asked to eat three apples a day lost weight instead of gaining, and concluded that choosing the right foods matters more than shrinking portions⁸⁶. In 2022 he said even very sweet fruits such as mango, papaya or blueberries release their sugar gradually, at a pace the body can use⁸⁷.

What all the experts say about fruit

Vegetables and greens

In the 2024 Power Foods talk Barnard said cruciferous vegetables such as broccoli, cauliflower and Brussels sprouts ranked second in the Harvard weight data, with other greens like spinach and asparagus third⁸⁸. On a podcast early that year he added that cruciferous vegetables bring an anticancer effect through sulforaphane, which prompts the liver to make more detoxifying enzymes within a day or two, while a serving of broccoli gives about 5 grams of fiber for roughly 55 calories⁸⁹.

Asked in 2021 to name a favorite green, he voted for variety, rotating spinach, broccoli, Brussels sprouts and kale⁹⁰. In 2020 he said raw cruciferous vegetables often upset digestion, so people with such problems might cook them, and their beans, a little longer⁹¹.

What all the experts say about vegetables and greens

Beans and lentils

Asked in 2021 whether beans help with weight loss, Barnard said yes: well cooked beans pose no lectin problem, their carbohydrate has 4 calories per gram against 9 for fat, and as the leading fiber source they fill people up⁹². He added that his team found beans, within a plant-based diet, modestly raise the calories burned after a meal⁹³.

In the same session he said soaking beans for 8 to 10 hours mainly shortens cooking time rather than improving nutrient absorption⁹⁴. In the 2024 Power Foods talk he called beans the fiber champions and urged bringing them back to the table⁹⁵.

What all the experts say about beans and lentils

Whole grains, bread and flour

In a 2022 Q&A Barnard pointed to Japan in the 1960s, where people ate rice at nearly every meal with little meat, dairy or oil and were among the slimmest in the world until fast food and dairy arrived⁹⁶.

In 2023 he gave refined white pasta a not guilty verdict next to the meat sauce poured over it, but said whole grain spaghetti is better because it restores the fiber⁹⁷. In 2021 he named oatmeal and bran cereal as foods that keep blood sugar steady, and said even white pasta does fairly well⁹⁸. In 2023 he cited a Tufts study comparing brown rice with white rice, in which the fiber both curbed appetite and carried unabsorbed calories out of the body⁹⁹.

What all the experts say about whole grains, bread and flour

Potatoes

Asked in 2021 whether pasta, potatoes or bread clog arteries, Barnard said the starch is not the problem: a potato has no cholesterol and almost no saturated fat until butter, cheese and bacon bits go on top¹⁰⁰. He made the same point in 2022, calling French fries and potato chips sponges of grease rather than carbohydrate foods¹⁰¹.

On blood sugar he said in 2021 that white potatoes are fine but sweet potatoes are better, and that eating a potato with black beans softens its effect¹⁰². In 2022 he noted that the sweet potato is the staple of Okinawa, the place with the most centenarians¹⁰³. He has also said a large potato carries more protein than a large egg⁶¹.

What all the experts say about potatoes

Meat

In 2025 Barnard said processed meats such as bacon, sausage, hot dogs and ham clearly raise colorectal cancer risk, and are also strongly tied to diabetes and even to chronic lung disease¹⁰⁴. Unprocessed steak or chicken, he added, is linked with diabetes too, if less strongly¹⁰⁵.

In 2022 he said red meat can slow the metabolism because it has no fiber or complex carbohydrate, and that red meat, chicken and salmon all carry enough fat to hamper the cell’s mitochondria¹⁰⁶. In another 2022 session he described a stepwise drop in body mass index from daily meat eaters to semi vegetarians, fish eaters, lacto-ovo vegetarians and finally vegans¹⁰⁷.

What all the experts say about meat

Low-fat eating

In 2021 Barnard said moving from chicken fat to olive oil is a real improvement, but that every oil still carries 9 calories per gram, so for weight control, diabetes or hormone related problems he advised a vegan diet without added oils¹⁰⁸. He said there is no need to count fat grams, but suggested setting aside packaged foods with more than about 3 grams of fat per serving¹⁰⁹.

In 2026 he described a study his team published in 2020: on a low-fat vegan diet with oils kept very low, participants lost about a third of the fat in their liver cells in 16 weeks, and fat left their muscle cells too¹¹⁰. As the fat came out of the food and the cells, he said, the mitochondria worked better and calorie burn rose within days¹¹¹.

What all the experts say about low-fat eating

Saturated fat

In his 2014 Alzheimer’s talk Barnard described Chicago research in which people eating about 25 grams of saturated fat daily faced over three times the Alzheimer’s risk of those eating about 13 grams¹¹². He showed how easily that level is reached with a couple of eggs, a strip of bacon, a skinless chicken thigh, a glass of milk and a personal pizza¹¹³.

In 2023 he called dairy the leading source of saturated fat, with most of the fat in cheese being saturated¹¹⁴. In 2021 he singled out coconut and palm oil as very high in saturated fat, though he had no objection to coconut oil used on the skin¹¹⁵, and in 2026 he named coconut milk as the one plant milk he would avoid¹¹⁶.

What all the experts say about saturated fat

Cholesterol

In 2021 Barnard reported his crossover trial: total cholesterol fell about 19 points on the vegan diet against 3 on the Mediterranean diet, and LDL fell 15 points against about half a point¹¹⁷. In another 2021 session he said a high HDL is no longer seen as the protector it once was, and that LDL is still the number to watch, with concern above 100¹¹⁸.

In 2023 he cited David Jenkins’s portfolio diet, a vegan diet with nuts, soy and soluble fiber foods such as oats and beans added, which cut cholesterol by about 30% in four weeks, close to what drugs achieve¹¹⁹. In 2022 he explained that plants contain no cholesterol, that avoiding animal fat means the body makes less of it, and that fiber helps remove what is already there¹²⁰.

What all the experts say about cholesterol

Carbohydrates and low-carb diets

In a 2017 talk Barnard said low carbohydrate diets do cause weight loss, simply because carbohydrates supply most of a typical person’s calories¹²¹. But the Atkins approach is very high in saturated fat and cholesterol, and he cited a six month Duke study in which 12 participants saw their LDL rise despite losing weight, by 18 points on average¹²².

In 2023 he said cutting out carbohydrate means removing fruit, starchy vegetables, beans and grains, and that a UK Biobank analysis found people on low-carbohydrate, high-fat diets had about double the risk of heart attack, stroke and peripheral artery disease¹²³. He listed constipation and an acetone smell as the minor effects and rising cholesterol and higher heart and cancer risk as the major ones, calling the evidence strongly against ketogenic diets¹²⁴.

What all the experts say about carbohydrates and low-carb diets

Gluten and wheat

In 2014 Barnard said gluten intolerance is not very common, perhaps 7% of people, and can show up as digestive trouble and brain fog; he did not suggest most people avoid gluten, but said those with brain fog could try going without it and bring it back if nothing changes¹²⁵.

For rheumatoid arthritis he described a two step approach in 2020: four weeks fully vegan and low in fat, then, if joints still hurt, a temporary elimination of common triggers such as wheat and other gluten grains, citrus or tomatoes, as set out in his book The Cheese Trap¹²⁶.

What all the experts say about gluten and wheat

Coffee, tea and caffeine

In 2020 Barnard said he does not drink coffee himself and called the research mixed: about five cups a day seems to lower Alzheimer’s risk¹²⁷, while caffeine can aggravate heart rhythm problems, disturb sleep and change mood; he judged caffeinated drinks not the worst problem, but unnecessary¹²⁸.

In 2021 he said caffeine is addictive and puts people on a daily roller coaster of highs and withdrawal headaches, yet expected coffee to be cleared on heart disease, cancer and diabetes¹²⁹. In 2023 he said caffeine raises blood pressure only modestly, and less as people grow used to it¹³⁰. In March 2024 he said caffeine lifts the metabolism a little, an effect the body adapts to, and warned that a milky latte can matter more than the coffee itself¹³¹.

What all the experts say about coffee, tea and caffeine

Alcohol

In his 2014 Alzheimer’s talk Barnard noted that light drinkers have slightly lower Alzheimer’s risk than abstainers or heavy drinkers, then asked whether the grape rather than the alcohol is the active factor, citing a Cincinnati trial in which grape juice improved learning and recall in older adults¹³².

In 2020 he told a pregnant listener to stop even an occasional glass of red wine¹³³. In March 2024 he said alcohol slows the metabolism among its other harms, and suggested a virgin cocktail or water instead¹³⁴.

What all the experts say about alcohol

Chocolate

Asked in 2021 about a little dark chocolate each day, Barnard said chocolate has some saturated fat; a small taste is unlikely to matter, but a nightly binge of candy bars adds enough to show on both the scale and the cholesterol test¹³⁵.

In a talk posted in 2019 he described how naloxone, the drug that blocks opiate receptors, takes away the urge in people who crave chocolate, and argued that chocolate acts more like a mild drug than a food¹³⁶.

What all the experts say about chocolate

Juicing and smoothies

In March 2024 Barnard said canned concentrate and fresh squeezed juice are about the same, and that Harvard data linked citrus juices, not only whole citrus fruits, with weight loss¹³⁷. Their glycemic index is not very high, he said, so he gave juice a not guilty verdict¹³⁸. In the 2024 Power Foods talk he likewise said the whole fruit is best but juice still counted¹³⁹.

In 2020, asked about smoothies and diabetes, he explained that cooking or blending fruit partly digests it in advance, so its sugars reach the blood faster¹⁴⁰.

What all the experts say about juicing and smoothies

Organic food and pesticides

In 2020 Barnard said organic produce is always better when there is a choice, and that money saved by not buying cheese and steak can pay for it¹⁴¹. He uses the Environmental Working Group’s pesticide lists and considers organic most worthwhile for delicate above ground foods eaten whole, such as spinach and other leafy greens, and less important for root vegetables or fruits that are peeled¹⁴².

What all the experts say about organic food and pesticides

Mediterranean diet

In a 2021 talk Barnard traced the diet to Ancel Keys’s studies in Italy: olive oil in place of butter, some dairy and eggs, little red meat and daily wine; he said modern versions picture it as far oilier than Keys did¹⁴³. In the PREDIMED study, he noted, participants who leaned furthest toward a vegetarian pattern had the lowest death rates, including from heart disease¹⁴⁴.

In his own crossover trial, he reported, people lost an average of 6 kilograms in 16 weeks on a low-fat vegan diet and nothing on the Mediterranean diet, though blood pressure improved on both¹⁴⁵. He has also called adding extra olive oil to a Mediterranean diet a mistake¹⁷.

What all the experts say about mediterranean diet

Weight loss

In 2020 Barnard said participants in his studies typically lose half a pound to a pound a week on a low-fat vegan diet without exercising or limiting portions, and that he would not restrict portion sizes unless a person has particular eating issues¹⁴⁶. In 2023 he said diet matters more than the gym for weight, since in his studies people lost weight with no change in exercise because fiber rich foods fill them up¹⁴⁷.

In his 2021 crossover trial the vegan phase brought an average loss of 6 kilograms in 16 weeks, against none on the Mediterranean diet¹⁴⁵. He has also described body weight falling step by step from meat eaters to vegans in population studies¹⁰⁷.

What all the experts say about weight loss

Cravings and food addiction

In a 2017 talk Barnard said alcohol, tobacco, cocaine and certain foods all trigger dopamine release in the brain’s pleasure centers¹⁴⁸. In one of his diabetes studies, he said, genotyping found that nearly half the participants carried a gene variant linked to fewer dopamine receptors, and he theorized that such people turn to chocolate, cheese, meat or overeating, gain weight and then develop diabetes¹⁴⁹.

In another 2017 talk he said cheese hooks people partly because digesting casein releases casomorphins, opiate compounds that reach the brain receptors heroin uses¹⁵⁰. He described dairy marketing programs run with the US government that set out to trigger cheese cravings¹⁵¹, and argued that a food that is both fattening and addictive, as he sees cheese, is a major driver of obesity¹⁵².

What all the experts say about cravings and food addiction

Exercise

In March 2024 Barnard said exercise has many benefits but should be added on top of a change in diet rather than replace it, since the body tends to make up the calories afterwards¹⁵³. In 2022 he said exercise raises the metabolism only while it lasts¹⁵⁴.

In 2025 he said working muscles can take glucose out of the blood with little or no insulin, and that it helps the heart, but that his studies kept exercise unchanged and people still improved, so diet can work for those who cannot exercise yet¹⁵⁵. In 2026 he cited studies finding more arterial plaque in long distance runners than in sedentary people, saying athletes fueling on the wrong foods can still run into trouble¹⁵⁶.

What all the experts say about exercise

Heart disease

In 2022 Barnard called a plant-based diet the best prescription for the heart, since plants have no cholesterol, avoiding animal fat lowers the body’s own cholesterol output and fiber helps clear it¹⁵⁷. He credited Dean Ornish with showing that narrowed arteries can open up again on a plant-based diet¹⁵⁸.

In 2023 he described the UK Biobank finding that low-carbohydrate, high-fat dieters had about double the risk of heart attack and stroke¹²³. In 2025 he said heart disease and cancer remain the two leading causes of death and that animal foods are a large contributor to both¹⁵⁹.

What all the experts say about heart disease

High blood pressure

In a 2023 session on blood pressure Barnard said cutting sodium always helps, but that fat also matters because it thickens the blood¹⁶⁰. His top foods for lower blood pressure were green vegetables such as broccoli and bok choy, berries and orange vegetables¹⁶¹, followed by rice in place of fatty staples and black or pinto beans for their minerals¹⁶².

In the same session he said regular exercise brings blood pressure down¹⁶³. In 2021 he reported that blood pressure improved on both the vegan and the Mediterranean diet in his crossover trial¹⁶⁴.

What all the experts say about high blood pressure

Diabetes

In a 2018 interview Barnard explained type 2 diabetes as fat building up inside muscle and liver cells and blocking insulin’s signal, so sugar cannot get in¹⁶⁵. He said the National Institutes of Health funded his team in 2003 to test a low-fat vegan diet, and that removing dietary fat lets cell fat fall and insulin sensitivity return¹⁶⁶. For type 2 diabetes, he said, sugar is not the main culprit¹⁶⁷.

In 2022 he reported that in the NIH trial the A1c measure of blood sugar improved on both diets but threefold as much with the vegan one as with a conventional diabetes diet, and that one early participant lost 60 pounds, stopped his medicines and saw his A1c drop from 9.5 to 5.3¹⁶⁸. In 2025 he added that processed and unprocessed meats are both linked to diabetes risk¹⁶⁹.

What all the experts say about diabetes

Cancer

In 2020 Barnard described Dean Ornish’s trial in men with slowly growing prostate cancer: PSA rose about 6% in the control group and fell about 4% in the group on a vegan, low-oil diet, which he linked to lower IGF-1¹⁷⁰. He stressed that this does not replace medical care¹⁷¹.

In 2025 he said processed meat clearly raises colorectal cancer risk¹⁰⁴. In early 2024 he credited cruciferous vegetables with a specific anticancer effect through sulforaphane⁸⁹. In a talk posted in 2019 he said more fat in a woman’s diet or body means more estrogen, which can drive breast cancer cells to grow¹⁷².

What all the experts say about cancer

Dementia and the brain

In his 2014 talk on avoiding Alzheimer’s disease Barnard set out three steps: avoid bad fats, counter free radicals with antioxidant foods, and exercise both brain and body¹⁷³. He cited Chicago data tying a higher saturated fat intake to more than triple the Alzheimer’s risk¹⁷⁴, and a low vitamin E intake to double it⁶⁶.

In the same talk he cited a trial in which grape juice improved memory in people with mild cognitive impairment¹⁷⁵, and a University of Illinois study in which walking three times a week reversed age related brain shrinkage¹⁷⁶. In 2021 he said about five cups of coffee a day goes with a much lower Alzheimer’s risk¹⁷⁷.

What all the experts say about dementia and the brain

Longevity and aging

In 2025 Barnard noted that US life expectancy is falling and recalled Gary Fraser’s Adventist Health Study, which suggested a healthy diet and lifestyle could add up to a decade of life, with vegan and plant-based diets the ones to prefer¹⁷⁸.

In a talk posted in 2019 he said vegetarians clearly live longer than meat eaters, though there were too few studies of vegans to separate them, and that healthy eaters tend to stay well into old age with a short decline at the end¹⁷⁹. In 2022 he pointed to Okinawa, home to the most centenarians, where the sweet potato is the staple food¹⁰³.

What all the experts say about longevity and aging

Each small number links to its reference at the bottom of the page: the video at the exact second, or the page where it was said.