Vegetarianism

The goal of making a vegetarian diet work revolves around selecting foods that are naturally low in polyunsaturated fatty acids (PUFAs), managing essential nutrients that may be limited in a plant-based approach, supporting thyroid function, and avoiding potential antinutrients and excessive estrogenic substances. This page provides a comprehensive overview of how to approach a high plant-based diet from a bioenergetic perspective.

This page focuses on the nutritional and metabolic mechanics of vegetarianism, not the ethical case for or against it. Ethical, ecological, and mechanistic arguments for plant-based eating are separate questions, and conflating them tends to produce bad nutrition advice; the mechanisms below apply regardless of why someone chooses the diet.

"Although plants produce all the amino acids needed by animals, the limited present knowledge and technology aren't sufficient to make a vegan diet both economical and nutritionally adequate, the children of vegan women are often affected by an insufficient supply of protein in particular."

Overview and principles

Vegetarian diets can support health when carefully constructed, but they require more attention than omnivorous diets due to several physiological realities:

• Plant proteins contain fewer essential amino acids and are less bioavailable than animal proteins
• Critical nutrients (B12, zinc, iron, iodine) are either absent or poorly absorbed from plant sources
• Many plant foods contain antinutrients that interfere with mineral absorption
• Legumes and soy introduce significant estrogenic compounds
• Vegetarians often default to seed oils, increasing PUFA burden

The lacto-ovo approach (including eggs and dairy) resolves most of these issues and represents the most sustainable form of vegetarianism from a bioenergetic standpoint.

"The protein content of milk is about 3%, which according to the charts would suggest that it is inferior to beans and grains. In fact, the protein value of grain is negligible, mainly because seeds contain their protein in a storage form, that is extremely rich in nitrogen, but poor in essential amino acids... Animal proteins, and fruits, because they contain the lowest levels of toxins, should form the basis of the diet."

Nutritional reference tables often mislead by comparing dry, concentrated seed protein to the wet weight of low-toxin foods:

"While nutritional reference tables often show fruits and potatoes as having about 2% protein content, while nuts, grains, and legumes are shown with a high protein content, often in the range of 15% to 40%, they neglect to point out that fruits and potatoes have a very high water content, while that of the seeds is extremely low."

Protein quality and amino acids

The quantity problem

Vegetarians tend to decrease both quantity and quality of protein simultaneously:

The average American is eating 80 to 90 grams of protein per day... the average vegetarian is eating around 60. So they're decreasing the quantity and also the quality at the same time.

The quality problem

Animal proteins are about 50% essential amino acids, plant proteins are about 35%. Ranging from something like almonds, which is quite low and only about 26%, up to soy, which is high at about 40% making them less anabolic

The practical implication:

30 grams of protein from whey protein at a meal is very different than soy protein or wheat protein, plant proteins are 20-30% less effective, so you'd have to be at 130-135 grams to be equal to 100g of animal protein

A retrospective study by Fort found that 31% of children with autoimmune thyroid disease had been fed soy formula in infancy, compared to 12% of siblings and 13% of controls. Raw/unheated soy protein isolate enhanced pancreatic carcinogenesis in rat models more than high-corn-oil diets, via trypsin inhibitors and CCK elevation, while heated forms did not; a pilot human study reported increased breast fluid secretion, erratic plasma estradiol elevations, and epithelial hyperplasia in 29% of women consuming soy protein isolate (~75 mg isoflavones/day). Consumer reports investigations found that plant protein isolates often contain higher heavy metals like cadmium (up to 5×) and lead (up to 3×) than whey isolates due to soil absorption and processing concentration, with whey typically ~90–97% pure protein vs. many plants ~70–90%. Early soy exposure in male rodents showed genital feminization effects (e.g., smaller testes, altered AGD) at high genistein doses, but no human evidence supports genitalia feminization or increased pituitary/reproductive tumor risk from typical soy formula. At meals, 30g whey protein stimulates muscle protein synthesis more effectively than soy or wheat due to superior leucine/digestibility; plant proteins are often ~20–30% less efficient per gram, requiring higher intake to match animal protein anabolic effects in some acute studies, though long-term outcomes equalize with adequate total protein.

Stick to milk and egg proteins if you can.

Whey and soy protein powders are industrial by-products, not whole foods, and carry their own risks:

"Whey, soy protein, and other industrial by-products sold as protein supplements aren't safe."

Leucine requirements

People over the age of 40 need about three grams of leucine per meal to maintain muscle health... if you go to a plant-based diet especially one that's grain based... 80 percent of the plant-based protein in the world comes from wheat and wheat is extremely unhealthy in the sense of amino acids: lysine, methionine, leucine are all very low in wheat protein Leucine stimulates insulin and is anabolic.

Minimizing problematic amino acids

Certain plant-based diets are beneficial because they are inherently lower in amino acids like methionine, which has been associated with reduced longevity when consumed in excess.

Tryptophan intake should be considered, as high levels can raise brain serotonin. Tryptophan can be lowered by ensuring adequate intake of competing large neutral amino acids (LNAA). Casein and gelatin provide these competitive amino acids.

Protein from plant sources

Nitrogen balance has been shown around 35 grams of protein per day for a 70 kg person as a minimum, but this is far below optimal for muscle maintenance.

Ray Peat repeatedly identified only two non-animal foods as adequate, complete sources of protein: potatoes and mushrooms.

"It happens that the only non-animal proteins that are really adequate for human needs are potatoes and mushrooms. And you can thrive as far as protein goes with either potatoes or mushrooms. And mushrooms happen to generally have more of the trace minerals than potatoes. So you can get your iron from the mushrooms and all of the other nutrients except B12 and vitamin A from potatoes."

Asked directly on a call-in radio show whether a vegan diet can be healthy:

"The closest you can come to it would be eating potatoes and mushrooms. Mushrooms are very similar to animal protein. And your intestine can make vitamin B12, which is sometimes deficient in a vegan diet... with the trace minerals of mushrooms and the high quality proteins and vitamins of potatoes, you can do pretty well. But most vegans don't do very well."

The same protein-table distortion applies to mushrooms as to potatoes and milk: dietician charts compare their high water content against the dry weight of beans and grains, making the mushroom/potato protein content look far lower than it functionally is.

"The typical dietician chart shows potatoes and mushrooms as having insignificant amounts of proteins... what they're doing is comparing the dry state, no water, to the wet state of the mushroom and potato, which are 80 or 90 percent water. So if you multiply by five or ten times the protein, then you get something that you could compare to the bean protein... I would compare it to milk."

Other plant sources that contribute protein:

• Coconut: 13g per coconut
• Pineapple: 5g per pineapple
• Leaves: abundant protein, chemically similar in nutritional value to milk protein

"The amino acid composition and nutritional value of leaf protein is similar to milk protein, which is understandable since cows produce milk from the amino acids produced in their rumens by bacteria digesting the leaves the cows have eaten."

— Ray Peat

"Potato protein slightly exceeds egg protein for quality."

— Ray Peat

Fruit is not a complete protein source, but several fruits are low in tryptophan while still containing "carbon skeleton" (keto-acid) equivalents of other essential amino acids, which the body can convert to protein:

"Many fruits are deficient in tryptophan, yet have very significant quantities of the other amino acids. They also contain some of the 'carbon skeleton' (keto-acid) equivalents of the essential amino acids, which can be converted to protein in the body."

Essential nutrients often lacking

Vitamin B12

This is the single most critical deficiency concern for vegetarians and especially vegans.

"B12 is an absolutely essential vitamin. You can't get it at all from plants. So you have to either supplement or get it from animal source foods. A serious B12 deficiency results in neurological damage and brain damage. So it is extremely serious."

The rates among those avoiding animal products are striking:

The rates of B12 deficiency among vegans and vegetarians is about 70 percent of vegetarians and over 90 percent of vegans if high-quality rigorous functional markers of B12 deficiency are used.

B12 has a long storage capacity, which can mask deficiency for years (up to 10). An Austrian study found elevated plasma homocysteine in 66% of vegans versus 45-50% of omnivores and vegetarians, though folate deficiency was actually more common among omnivores (18%) than vegans or vegetarians (~10%).

Sources: Eggs and dairy provide B12 for lacto-ovo vegetarians. Strict vegans must supplement. Bacteria in the human colon produce B12, but absorption without intrinsic factor is questionable.

Dosing: 1000-2000 mcg sublingual or 250 mcg daily oral. Non-negotiable for vegans; recommended for all vegetarians.

Zinc

Zinc and iron deficiencies are highly correlated in vegetarians due to overlapping absorption inhibitors:

A vegan likely needs twice as much zinc as an omnivore needs because of the inhibitory effect of phytate and the beneficial effect on zinc absorption by the amino acid composition of most animal proteins. And so vegan foods are arguably intrinsically inferior to animal proteins as sources of zinc.

"If someone's not getting enough zinc they're not getting enough iron and vice versa... A vegan diet is very high in iron absorption inhibitors, very high in zinc absorption inhibitors, very low in zinc." (Chris Masterjohn)

Dosing: Vegetarians with confirmed low zinc should supplement with 15-30 mg zinc, taken with phytate-free meals.

Iron (heme vs non-heme)

Plant iron (non-heme) is fundamentally different from animal-source iron (heme):

The biggest inhibitors of iron absorption are phytate and polyphenols and plant protein. And there are no plants that are high in iron that are not high in those factors. Generally, iron status is good when there's more animal foods and less plant foods in the diet.

Strategies:

• Coffee and tea with meals reduces iron absorption (useful if iron is high, problematic if deficient)
• Vitamin C enhances non-heme iron absorption
• Separate iron-rich meals from phytate-rich foods
• Egg yolks promote iron absorption; egg whites inhibit it

"Drinking coffee with meals will greatly reduce iron absorption." (Ray Peat, email)

Dosing: Only if confirmed deficient; take with vitamin C, away from phytates.

Iodine

Daily consumption of leaves can supply calcium requirements, but when eating Brassica vegetables regularly, iodine supplementation becomes important to counteract goitrogenic effects. See Cruciferous vegetables below for cultivar and cooking detail.

Sources: Kelp tablets, iodized salt, seafood (for pescatarians). Dosing: 150-300 mcg, especially if consuming goitrogenic vegetables.

Calcium

"Daily consumption of leaves can supply the RDA for calcium."

Milk remains the most bioavailable source. Two quarts of milk daily provides excellent calcium along with other protective factors. Calcium deficiency, not fat or cholesterol, is the specific weakness Ray Peat identified in near-vegan populations. Asked what strict vegans are typically deficient in:

"Oh, calcium... They break bones too easily once they get to be 60 or 70."

He cited the Fulani of Africa as an example of a population close to vegan, and unwell:

"Some people have studied the Fulani people of Africa and found that they were pretty close to vegan but very sick, lots of heart disease... probably because of the calcium deficiency."

No indigenous culture is fully vegan; some vegetarian cultures exist in hot climates where meat preservation is difficult and fruit is abundant, but a strict plant-only diet does not appear as a stable traditional pattern anywhere. For vegetarians who cannot get enough calcium from milk, boiling leafy greens and drinking the cooking water extracts usable calcium and magnesium, and baking soda added to the cooking water neutralizes oxalic acid (present in spinach, chard, and to a lesser extent kale) that otherwise blocks calcium absorption:

"Leafy greens, if you cook them thoroughly and save the water, are a good source of calcium and magnesium... About a pound, I think. You'd have to boil a pound down a day... another way to help get the minerals out of the greens, especially those with oxalic acid... is put baking soda in it. And that helps neutralize oxalic acid because oxalic acid that's in spinach and chard blocks your absorption of the calcium."

Eggshell calcium powder

Easy source of calcium carbonate, which is the same form calcium takes in bone and analyses show they have the lowest concentration of heavy metals compared to oyster shell or bone meal supplements. Old cow bones used for supplements can have surprisingly high lead content, so eggshells are actually the cleaner choice with superior absorption over pure calcium carbonate as proven by multiple studies.

Dosing: About a quarter teaspoon three times daily with meals provides roughly 2,000mg of calcium. The stomach acid from eating helps absorption. Taking it with some sugar or fruit (like orange juice) further improves uptake.

Eggshell calcium recipe. More in Calcium.

Vitamin A and beta-carotene

Vitamin A conversion from plant carotene depends on adequate thyroid function and B12:

"Vitamin A is just needed for making progesterone, which is essential for maintaining good periods... the problem becomes that so many vegetables block your thyroid function. As long as you can keep your thyroid functioning and have vitamin B12, then you can convert carotene adequately to vitamin A to make your hormones."

Excess carotene in a diet very low in preformed retinol is not automatically safe, and can itself become anti-thyroid:

"In a vegetarian diet containing very little vitamin A as retinol, carotene can sometimes become toxic, since its conversion to retinol requires vitamin B12 and other liver functions that seem to depend on adequate thyroid function, and excessive carotene can be anti-thyroid as well as anti-steroidogenic."

Creatine

Vegetarians typically have significantly lower creatine stores, muscle biopsies show some have only about 50% of their muscle creatine capacity filled compared to meat-eaters. This happens because creatine is found almost exclusively in red meat and seafood, and while the body synthesizes about 1 gram daily, that's rarely enough to maintain optimal stores, especially without dietary intake.

The fix is straightforward: supplement with creatine monohydrate, typically 3-5g daily (adjust based on body size). Vegetarians and vegans often see more dramatic benefits from supplementation precisely because they're starting from a more depleted state, improved strength, cognitive function, and muscle gains tend to be more pronounced in this population.

Other supplements to consider

Nutrient	When needed
Vitamin D	2000-5000 IU if sun exposure is limited
Selenium	From food or 100-200 mcg; supports T4 to T3 conversion
Vitamin K2	If not consuming fermented foods or animal fats
Gelatin/glycine	To balance amino acid overabundance from muscle-meat-heavy or dairy-heavy protein; see The gelatin issue
Magnesium	If experiencing cramps or sleep issues

Thyroid function and vegetarian diets

Thyroid health is particularly vulnerable in poorly designed vegetarian diets. A protein-deficient vegetarian diet is itself anti-thyroid, independent of any specific antinutrient:

"Vegetarians are sometimes dangerously deficient in protein, and in that state the body is very resistant to thyroid hormone."

Several more specific mechanisms converge to suppress thyroid function:

Cruciferous vegetables

Brassica vegetables release two distinct goitrogenic compounds. The thiocyanate ion competitively and reversibly inhibits iodine uptake in the thyroid, an effect obviated by adequate iodine intake; everyone carries a measurable baseline level of it in blood, and smokers run higher levels from cyanide metabolism. The more potent goitrogen is goitrin, released from a single glucosinolate (progoitrin) by the plant enzyme myrosinase.

Goitrin content varies sharply by species, not just by "crucifer" as a category:

• Higher progoitrin/goitrin (Brassica rapa and napus): rapeseed/canola, bok choy, mustard greens, collards, Brussels sprouts, and Russian kale (identifiable by its purple stem). Best avoided or eaten sparingly.
• Lower progoitrin/goitrin (Brassica oleracea): broccoli, curly and lacinato kale, cabbage, cauliflower. Minimal thyroid risk at ordinary intakes.

Cooking reduces but does not eliminate exposure: myrosinase is heat-denatured, but analogous glycoside hydrolases from gut bacteria can still release isothiocyanates from glucosinolates after ingestion. Cooked cabbage produces meaningfully less isothiocyanate excretion than raw cabbage in human subjects. Even low-goitrin crucifers should be well cooked and kept to about once a week, not eaten as a daily staple:

"The foods of the cabbage family, such as broccoli, should be well cooked, and used no more often than once a week."

When consuming these vegetables regularly, supplementing with iodine (such as kelp tablets) is recommended.

Soy

Soy formula in infants provides a cautionary example:

"In the 1960s, when soy was introduced into infant formulas, it was shown that soy was goitrogenic... A retrospective epidemiological study by Fort et al. showed that teenage children with a diagnosis of autoimmune thyroid disease were significantly more likely to have received soy formula as infants (31% vs 12-13% in controls)."

The mechanism extends beyond iodine interference:

"The oil itself has a pro-estrogen effect, anti-thyroid effect apart from the isoflavones."

Even healthy adults show effects:

"When healthy individuals without any previous thyroid disease were fed 30 grams of pickled soybeans per day for one month, Ishizuki et al. reported goiter and elevated individual thyroid-stimulating hormone levels... One month after stopping soybean consumption, individual TSH values decreased to the original levels, and goiters were reduced in size."

Estrogenic effects. The "weak estrogen is safe" argument does not hold up under scrutiny:

"Whether weak or strong, the estrogenic response of a chemical, if not overcome, will add extra estrogenic burden to the system... The potential of exposure for humans and animals to environmental estrogen-like chemicals is high."

Traditional soy foods differ from modern processed soy:

"Japanese women's relative freedom from breast cancer is independent of soy products: traditional soy foods aren't the same as those so widely used in the US, for example, soy sauce doesn't contain the so-called soy estrogens."

In males, soy consumption is linked to feminizing effects:

"Soy consumption in males has also been positively associated with things like gynecomastia which is another side effect of estrogen activity within males."

A maternal vegetarian diet during pregnancy has also been linked to a specific male birth defect, hypospadias, in a large UK cohort study, plausibly via phytoestrogen exposure. Mothers who were vegetarian in pregnancy had about five times the adjusted odds of giving birth to a boy with hypospadias.

Does heat treatment help? Yes, significantly for some compounds. The study comparing raw vs heat-treated soy protein isolate found that heat-treated soy protein isolate neither enhanced carcinogenesis nor elevated plasma CCK levels, while raw soy did both. So cooking/heat processing removes some of the worst acute toxicity (likely trypsin inhibitors and lectins). However, heat doesn't eliminate the isoflavones (phytoestrogens); those are heat-stable. Cooked tofu still carries the estrogenic burden, only some antinutrients are removed.

Ranking soy forms, worst to least bad:

1. Soy infant formula (developing bodies, high exposure; 31% of teenagers with autoimmune thyroid disease had received soy formula as infants, vs 12% of healthy siblings)
2. Raw soy protein isolate (concentrated toxicity; enhanced pancreatic carcinogenesis in animal models more than high corn-oil diets; caused epithelial hyperplasia in 29% of women in one study)
3. Soy oil (PUFA bomb, separate from the isoflavone issue; extremely high in linoleic acid, reliably causes diabetes and fatty liver in animal models)
4. Heated soy protein isolate (still estrogenic, but less acutely toxic)
5. Tofu (cooked but unfermented; thyroid effects documented at moderate intakes)
6. Tempeh/miso (fermentation helps somewhat, though isoflavones aren't fully eliminated)
7. Soy sauce (traditional fermentation appears to eliminate the isoflavones entirely; "It's safe in moderate amounts.")

Plant protein isolates in general also tend to contain heavy metals like cadmium and lead bound to the fiber fraction more than whey isolate does. If soy is used at all, traditional fermented forms (especially soy sauce) are the least problematic; soy protein powders and isolates are the worst, and cooking alone cannot remove the estrogenic compounds, only the acute antinutrient toxicity.

Supporting thyroid on a vegetarian diet

"The liver has to convert T4 to T3 for it to be effective. It needs glucose and selenium to make the conversion. Adequate protein, at least 80 grams per day, is necessary. Sea food, once a week will provide selenium, two quarts of milk and a quart of orange juice would provide many of the other essential nutrients."

— Ray Peat

Key supportive foods: milk, orange juice, coffee, adequate salt, and selenium-rich foods.

Antinutrients and absorption concerns

Phytates

Phytates (phytic acid) in whole grains, nuts, seeds, and legumes bind minerals and prevent absorption. This is the primary reason vegetarians require higher intakes of zinc and iron.

"Zinc is much more specifically inhibited by phytate, whereas iron is just broadly inhibited by plants, like almost everything that's in plants inhibits iron absorption, except vitamin C and organic acids." (Chris Masterjohn)

Legumes

Beans, lentils, and other legumes are treated by many "healthy" diets as a default protein source, but Ray Peat considered them one of the most anti-thyroid and immunologically disruptive plant foods, not just a source of phytates and resistant starch:

"Beans and lentils happen to be powerful anti-thyroid agents, so it isn't surprising to see indications of decreased aerobic capacity... in association with the chronic fatigue syndrome (CFS), if that syndrome is caused by chronic exposure to dietary legumes."

The bean lectin phytohaemagglutinin (PHA) and related legume extracts have documented immune and gut-barrier effects:

"An extract of the common bean (phytohaemagglutinin, PHA)... The effects of bean toxin, and other plant toxins... overlap in several ways with viral infection and autoimmune disease. PHA causes, for example, the appearance of large mononuclear cells in the blood, the suppression of DNA synthesis in thymic cells, a slight leucopenia, and hepatic necrosis. Extracts of lentils, broad beans, and fenugreek (used in curry) are as active as PHA, and extracts of common peas, chick peas, lupinus, and soy beans also have some activity."

A researcher cited by Peat went so far as to draw a parallel between bean-extract-stimulated lymphocytes and the cells of Burkitt's lymphoma:

Pulvertaft found "a close similarity between Burkitt cells and human lymphocytes stimulated by bean extract," and judged that "the possibility of a relation between Burkitt's lymphoma and a diet of beans should not be neglected," while emphasizing that other factors must be involved, since most bean-eaters don't develop the disease.

Legumes should be avoided or minimized in a therapeutic bioenergetic diet:

"Make sure her Calcium to phosphorus ratio is good, by having two quarts of low fat Milk per day... with no Grains, legumes, nuts, or muscle meats, and with some well cooked greens regularly."

"Intestinal Inflammation is often behind recurrent tooth infections, and a daily raw Carrot can make a big difference (along with avoiding legumes, undercooked starches and raw or undercooked Vegetables)."

If legumes are consumed despite these concerns, see Preparing food for preparation methods that reduce (but do not eliminate) their antinutrient load.

Lectins (wheat)

Plant defensive mechanisms, modern wheat contains significantly more gluten (a type of lectin) than heritage varieties:

"The wheat that's grown now by big agribusiness since World War II, particularly in the '70s, '80s and '90s, has almost 90% more gluten... these lectins are a plant protein which protect the seed of the plant. They're a sticky protein and make up part of the plant's natural immune system.... When they get in your body they don't know they're in your body, and they travel through your digestive tract, get into your bloodstream, and they're looking for a fight, because by nature they're designed to attach themselves to sugar molecules." - KMUD caller

Protection: Ordinary sugars like sucrose have a protective effect against inflammation-producing factors from lectins and polyunsaturated fats.

"Sucrose is better than even well-cooked starch at protecting the immune system from these irritants and toxins."

The general theory behind all plant defensive chemicals, including lectins, phenols, tannins, and trypsin-inhibitors: plants concentrate their toxins where an animal is most likely to attack and eat their reproductive material.

"In general, the plant's most intense toxins are in its seeds, and the fruits, when mature, generally contain practically no toxins... Special preparation is needed to reduce the toxicity of seeds, and in the case of beans, these methods are never very satisfactory."

This is why fruits, roots, and tubers are generally safer than seeds, grains, nuts, and legumes on a bioenergetic diet.

Hormonal considerations

Estrogen and progesterone balance

Estrogen promotes inflammation and interferes with thyroid function. Progesterone opposes estrogen's effects.

"Estrogen inhibits the release of active hormone, but it doesn't inhibit the creation of the protein called thyroglobulin, which leads to the active hormone. So a high estrogen person, late teens or around menopause, are the times that the estrogen can get out of balance."

Vegetarians consuming significant soy and legumes face an elevated estrogenic burden (see Soy and Legumes above). This can be partially offset by:

• Adequate progesterone-supporting nutrition (vitamin A, thyroid support)
• Avoiding PUFA (which promotes estrogen synthesis)
• Raw carrot salad (binds and excretes estrogen via bile)

No food directly supplies or promotes progesterone, despite popular claims about wild yam:

"Only things that provide energies, sodium, calcium and sugar are necessary for making the thyroid that you need to make the progesterone, but there are no foods that directly go to the progesterone system... the [chemical] in the yams is actually estrogenic and very toxic."

Digestive health

Fiber: soluble vs insoluble

Not all fiber is equal. Insoluble fiber is protective; soluble fiber can be problematic.

Insoluble fiber benefits:

"Insoluble fiber is what we need to consume... it both binds already present LPS and also has antibacterial effect against the microbiome. The latter effect helps reduce production of LPS, even when poorly digestible foods are consumed." - Haidut

Soluble fiber risks:

"Despite the reduction in weight seen in animals fed soluble fiber, at least 40% of them developed liver cancer (HCC). Even worse, when the soluble fiber was combined with high-fat diet, the HCC incidence rose to 65%."

Problematic soluble fibers include: pectin, inulin, fructooligosaccharides (FOS), guar gum, psyllium.

Safe fibers

Raw carrots have unique antibacterial properties:

"Raw carrots... if you've noticed that many vegetables will spoil in the refrigerator while carrots still seem to be completely clean and unattacked by bacteria or molds. That's because there are chemicals that are defensive for those plants. When we eat them, they remain like antibiotics all the way through our intestines."

"It can also bind some of the toxins produced by bacteria so that rather than increasing the amount produced, it can actually bind it and carry it out, subtracting toxins. It's almost like the activated charcoal that's used for detoxifying ingested chemicals. Carrots are a natural way of doing that."

Recommended safe fibers:

• Raw carrots (daily carrot salad) - Recipe
• Cooked bamboo shoots - Recipe
• Cooked mushrooms
• Well-cooked white button mushrooms - Recipe

Endotoxin and bacterial fermentation

Indigestible starches and fermentable fibers feed bacteria that produce endotoxin (lipopolysaccharide):

"Indigestible fibrous materials, types of starch that can't be broken down by animal enzymes or human enzymes become good food for bacteria... About 30 years ago, some Australian studies saw that people who ate a lot of oat bran actually were increasing their risk for bowel cancer."

Certain types of fiber cause such intense growth of bacteria that the bacteria produce many types of toxins, not just the fragment of the bacterial coat that's known as endotoxin, but they can produce modified proteins, modified fats and so on from indigestible food.

— Ray Peat

Transit time matters:

"Because there was a lot of potato in the diet of the Africans and other fibrous foods, their transit time on average was about 12 hours from in to out. The average American at the time the study was done had a transit time of 72 hours."

Physical activity supports intestinal motility:

"People who live in apartments have to take their dogs out for a walk every day because the digestive system tends to slow down when you aren't walking. There are reflexes between especially the legs and the intestine."

PUFA and fat considerations

The vegetarian PUFA problem

Vegetarians often default to seed oils for cooking, dramatically increasing PUFA intake. This creates multiple problems:

"PUFA (and linoleic acid in particular) as the cause of breast, colon, prostate and other cancers. It also provides evidence for greatly increased serum estrogen levels in organisms fed even normal-fat diet with a significant PUFA content."

"When the polyunsaturated fats in the diet are reduced, the amount of them stored in the tissues decreases for about four years, making it progressively easier to keep the metabolic rate up, and stress hormones down."

PUFA sources to avoid

• Soybean oil
• Corn oil
• Safflower oil
• Sunflower oil
• Cottonseed oil
• Most nut oils (except macadamia)
• Most nuts and seeds (high PUFA)

Of nuts specifically, only macadamias are considered reasonably safe on this basis:

"Nuts have a lot of polyunsaturated fatty acids that are very estrogenic... the only nuts that I know of that are fairly safe for the fats would be the macadamias. They're pretty saturated."

Safe fats for vegetarians

"Coconut (oil and whole) is highly favored for its high saturated fat content and low PUFA content (around 1-3%). Coconut is considered the premier tropical saturated-fat source." (Original wiki content)

Recommended fats:

• Coconut oil (1-2% PUFA)
• Butter
• Cocoa butter/chocolate fat (mostly stearic acid)
• Olive oil (~10% PUFA, mostly monounsaturated)
• Macadamia nuts (low PUFA for a nut)

"Monounsaturated fats are fine. They're a part of our nature. If we eat nothing but sugar, we'll make monounsaturated fats of our own. And those are the N-9 fats like in olive oil and butter."

Omega-9 production

When PUFA intake is minimized, the body produces its own beneficial omega-9 polyunsaturated fats (mead acid series) which have anti-inflammatory properties:

"From that N-9 series of fats, we produce our own polyunsaturated fats called the N-9 or the omega-9 series. And it's the lack of those partly which is the damage done when we eat things like soy oil and safflower seed oil... They inhibit our ability to produce our own polyunsaturated fats which are stable and beneficial."

The gelatin issue

Gelatin comes exclusively from animal collagen (bones, skin, connective tissue), so strict vegetarians cannot consume it. Since gelatin's tryptophan-balancing and gut-barrier benefits (see above and Digestive health) are otherwise hard to replace on a vegetarian diet, this is one of the few places where supplementation genuinely substitutes for a food-based nutrient:

Need	Animal source	Vegetarian alternative
Glycine	Gelatin, bone broth, collagen	Synthetic glycine powder (3-10g daily; 3-5g per meal for blood sugar stability, 3g before bed for sleep)
Tryptophan balance	Gelatin balances muscle meat amino acids	BCAAs (eggs, dairy, macadamia nuts), glycine, niacinamide (100-500mg with meals), small doses of aspirin with meals, dairy protein (if lacto)
Gut barrier support	Bone broth	Glycine + insoluble fiber + vitamin E + coconut oil
Collagen synthesis	Collagen peptides	Egg membrane collagen (rich in glycine, proline, hydroxyproline) / Glycine + vitamin C + copper + adequate protein

Gelatin itself is absorbed better than isolated glycine, and Ray Peat generally did not recommend supplementing isolated amino acids over whole-food sources; taurine is a partial substitute for those who cannot tolerate gelatin or glycine, sharing some of glycine's anti-inflammatory and calming properties. Endogenous glycine synthesis from glucose depends on adequate vitamin B6, folate (not just methylfolate), niacin (for NAD+), and B12, the last of which vegetarians are already prone to running short on, compounding the problem.

Making vegetarianism work

The critical role of eggs and dairy

Eggs and dairy resolve most of the nutritional challenges of vegetarian diets:

"I've changed my stance on dairy, I've changed my stance on eggs because I've realized... even the American Heart Association says if you're vegetarian you want to eat eggs that's actually really healthy, it's heart healthy." (Dr. Amy Shah)

Eggs:

"It's considered the highest quality protein of all."

Eggs from well-raised chickens (pastured, eating bugs and vegetables rather than corn and soy) are superior:

"When I'm in Mexico and know where the eggs come from, the chickens get tortillas and vegetables and lots of bugs and so on, then I'll eat four or five eggs a day and it's okay to eat more."

Timing consideration: Eggs can lower blood sugar, which may disrupt sleep if eaten at night without adequate carbohydrates:

"Eggs at night... tend to hold your blood sugar down all night... many people told me the same effect."

Solution: Combine evening eggs with adequate sugar (fruit, orange juice, or ice cream).

Labeling note: "Vegetarian-fed" on an egg carton typically means the hens were fed a soy-based (rather than fishmeal-based) feed, not that the feed is otherwise better; it does not indicate a low-PUFA diet for the hens, since soy feed is a significant PUFA source. Egg yolk fatty-acid composition follows the hen's diet, so this label is not a useful proxy for PUFA content.

Egg whites vs yolks:

• Egg yolk protein promotes iron and zinc absorption
• Egg white protein inhibits iron absorption
• Egg whites contain avidin, which binds biotin
• For those eating many eggs daily, emphasizing yolks is preferable

Dairy:

"The calcium, accompanied by some saturated fat, is a major benefit of milk and cheese."

— Ray Peat

"I have averaged two quarts a day for a long time."

— Ray Peat

Milk provides: calcium, high-quality protein, B12, saturated fat, and thyroid-supporting factors.

A1 vs A2 milk: Some people react to A1 beta-casein in conventional cow dairy but tolerate goat, sheep, or A2 cow milk well.

More in Milk.

Preferred foods and food selection

Fruits and tubers:

Good quality, consistently available fruits include:

• Pineapples (Del Monte being consistently good)
• Caribbean papaya (Asian papaya is considered "iffy")
• Oranges and orange juice
• Ripe tropical fruits

Leaves (greens):

Eating leaves is recommended, both raw and sometimes steamed. Raw kale, arugula, and spinach are specifically mentioned. A pound of raw kale alone contributes significantly to daily nutrition, including:

• Folate (easily exceeded by consuming leaves)
• Calcium (can supply RDA)
• Vitamin A as beta-carotene (conversion is tightly regulated to prevent toxicity; see above)

Starch and carbohydrates:

It is important to minimize refined carbohydrates and poorly digestible starches. Raw starches found naturally in some fruits and roots are preferred over cooked starch from grains and beans.

"Things like fruit are so quickly digested by most people. The liquid parts, minerals and sugars can be largely absorbed before you get down to the bacterial area of the intestine."

Well-tolerated starches:

• Well-cooked potatoes
• Well-cooked white rice
• Masa (nixtamalized corn)

Problematic starches:

• Beans and legumes (see Legumes above)
• Whole grains (phytates, lectins, difficult to digest)
• Undercooked potatoes

Safe carbohydrate sources

Fruits:

• Provide minerals that stabilize metabolism
• Sugar from fruit is turned into saturated fats by the body
• Fructose enhances glucose utilization

"Sugar, from whatever source, but especially from fruits because of the minerals that help to stabilize and organize the metabolism, sugar is naturally turned into saturated fats and we immediately create an omega-9 type of fat when we synthesize fat from sugar."

Dairy sugars:

• Lactose in milk
• Ice cream (high-quality brands like Häagen-Dazs or DIY)

Simple sugars:

• Honey
• White sugar (in moderation, with adequate minerals)
• Orange juice

Daily carrot salad

A cornerstone practice for vegetarians to support hormonal balance and digestive health:

Recipe:

• 1 medium raw carrot, shredded lengthwise
• 1 tablespoon coconut oil or olive oil
• 1 teaspoon vinegar
• Pinch of salt

Link to full recipe

Benefits:

• Binds endotoxin in the intestine
• Binds and helps excrete excess estrogen
• Provides antibacterial fiber
• Supports regular bowel movements

A daily raw carrot salad should keep the small intestine fairly sterile.

Preparing food

Proper preparation can reduce antinutrient content, though it cannot fully eliminate it, especially for beans:

"Special preparation is needed to reduce the toxicity of seeds, and in the case of beans, these methods are never very satisfactory."

For grains and legumes (if consumed):

• Soaking overnight reduces phytates
• Sprouting further reduces antinutrients
• Thorough cooking is essential
• Fermentation (as in traditional sourdough) reduces lectins and phytates

For vegetables:

• Cooking reduces goitrogen content in cruciferous vegetables (see above)
• Boiling leafy greens and drinking the cooking water, with a pinch of baking soda added to neutralize oxalic acid, improves calcium/magnesium yield (see Calcium above)
• Raw carrots retain their antibacterial properties
• Steaming preserves more nutrients than boiling

Link to recipe: Ray Peat's leafy greens

For eggs:

• Light cooking is fine
• Excessive cooking (hard, rubbery texture) may increase oxidation
• Raw egg yolks are well-tolerated by many

A note on fermented vegetables: unlike fermented soy, fermented vegetables (sauerkraut, kimchi) offer little independent nutritional benefit and carry a contamination risk:

"Some of them taste very nice, like sauerkraut. But I don't think there is much nutritional value in them. And there's a risk of getting bad fungus contamination in them. In Asia, where fermented vegetables are very popular, they've seen a lot of stomach and throat cancer that comes from the fungal contamination of fermented vegetables."

Long-term health outcomes

Bone fracture risk

The EPIC-Oxford cohort found vegans at 2.3 times higher hip fracture risk than meat-eaters, with vegetarians and pescatarians also elevated; the effect was substantially reduced by higher BMI and higher calcium and protein intake. A protein/calcium-deficiency mechanism fits better than something intrinsic to plant food itself.

Stroke risk

A large study found unexpected cardiovascular risks:

Vegans and vegetarians have a higher risk of stroke. The Oxford study, a major long-term research project looking at diet and health. Half of participants, recruited between 1993 and 2001, were meat-eaters, just over 16,000 vegetarian or vegan, with 7,500 who described themselves as pescatarian.

The elevated stroke risk likely relates to the increased estrogenic burden from plant-heavy diets and potential B12/homocysteine issues.

Depression and processed meat substitutes

Vegetarians who ate plant-based meat analogues (PBMAs, such as Beyond Meat) had a 42% higher risk of depression than vegetarians who avoided them, in a UK Biobank analysis, along with higher blood pressure and C-reactive protein and lower apolipoprotein A. Mushroom-based products were not implicated; mushrooms are nutritionally distinct from plant foods generally (see Protein from plant sources).

Cognitive function

The brain has high energy demands and depends on adequate B12, zinc, iron, cholesterol and even creatine:

The brain constitutes 2% of the body's weight, but 20% of its energy demand. Around two-thirds of that energy demand is to fuel the activities of neurons.

The Honolulu-Asia Aging Study found that men who ate tofu at least twice weekly in midlife had more cognitive impairment and lower brain weight decades later than men who rarely ate it, an effect roughly equivalent to five years of additional brain aging. Long-term vegetarians should monitor cognitive function and ensure adequate intake of brain-supporting nutrients.

Longevity research

"Humans have evolved and thrived over millions of years because of their significant consumption of meat... It highlights that meat has its own components contributing to our overall health beyond just the number of calories consumed, and that without meat in our diet, we may not thrive."

A separate cohort study similarly found meat-eaters more likely to reach centenarian age than vegans. Studies finding benefits from vegan diets often fail to account for socioeconomic factors:

"Educated, well-paid people in developed countries can spend time and money on finding plants that can somewhat mimic the composition and nutritional profile of meat, and thus have an overall beneficial effect on health. However, eating even those carefully chosen plant diets cannot match the full benefits meat eating has on health and lifespan."

— Haidut

The good and the bad (recap)

A condensed pro/con summary; each point is sourced and expanded in the sections above.

The good:

• Restricting protein intake lowers overabundant amino acids like histidine, methionine, and tryptophan
• Lower and better-absorbed iron load from plants (protective if iron is already high)
• Ton of fruit and natural sugar
• Vegetarians had 29% lower ischemic heart disease mortality in one cohort

The bad:

• B12 deficiency, calcium deficiency, low creatine stores, no dietary gelatin
• Very low protein bioavailability: up to 30% lower bioavailability and 40-60% lower cellular uptake/utilization compared to animal protein
• High PUFA load, especially from seed oils and fake meat products
• Elevated bone fracture and stroke risk, mainly tied to protein/calcium deficiency rather than plant food per se

Travis claims

B12, homocysteine, and birth defects

Citing "B-Vitamin Status and Concentrations of Homocysteine in Austrian Omnivores, Vegetarians and Vegans": vegans show slightly lower B12 and slightly higher homocysteine than omnivores, but higher folate. In Travis's view, a high-methionine, low-folate, low-choline diet (more typical of high-protein omnivorous eating) may raise homocysteine and cause more birth defects than vegan B12 shortfalls do, citing a primate study where plasma homocysteine rose from 4.06 to 10.66 μM on such a diet, and citing "Prevalence of Spina Bifida and Anencephaly During the Transition to Mandatory Folic Acid Fortification in the United States" to suggest vegans' higher folate intake may lower spina bifida risk. Travis could not find data directly comparing birth defect rates between the two groups.

Vitamin A from carotene

Travis argues vitamin A is "the last thing a vegan should worry about," citing a Cronometer estimate that one pound of kale provides 1500% RDA of vitamin A as carotene equivalents, and citing "Influence of vegetarian and mixed nutrition on selected haematological and biochemical parameters in children" as showing vegetarian children have higher serum vitamin C, E, and A than omnivore children. Separately, he offers his own re-derivation of a 2002 UC Davis beta-carotene absorption study (Hickenbottom et al.), arguing its reported ~4% mean beta-carotene-to-vitamin-A conversion rate is misleadingly low and that pre-formed retinol absorption looks comparably poor by the same method for some subjects.

Vitamin C and raw veganism

Extrapolating from endogenous vitamin C synthesis rates in animals that can synthesize it (cats, dogs) onto humans (who cannot), Travis argues humans likely need much more vitamin C than typically consumed, "except for some raw vegans perhaps" eating enough raw fruit to approach that level; he notes ascorbate is heat-labile so cooked/pasteurized foods lose most of it.

Protein adequacy from fruit

Citing Rand, Pellett & Young, "Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults" (Am J Clin Nutr 77.1, 2003): nitrogen balance is reached around 625 mg N/kg/day (~44g protein for a 70kg person), which Travis says is "easy to do with raw fruit and vegetables," though "with just fruit alone you can barely squeak by."

Methionine restriction as a pro-longevity argument for veganism

Cites McCarty, Barroso-Aranda & Contreras, "The low-methionine content of vegan diets may make methionine restriction feasible as a life extension strategy," Medical Hypotheses 72.2 (2009): 125-128, as a pro-vegan argument compatible with methionine/lifespan concerns. Elsewhere, in Travis's view, the low methionine, tryptophan, and linoleic acid intake of low-fat raw vegan diets "should make them almost cancer-proof," via a mechanistic chain (methionine to SAM to polyamines to cancer; tryptophan to pituitary to growth hormone to cancer; linoleic acid to arachidonic acid to eicosanoids to cancer).

Crohn's disease and IBD remission

Relaying an unnamed forum interlocutor's claim, sourced only to a Nutritionfacts.org video: vegetarian diets can put Crohn's disease and IBD into remission, possibly via reduced arachidonic acid intake.

Endotoxin counter-argument

In response to a claim that vegan diets raise endotoxin load, Travis counters: "Vegans eliminate the foods highest in endotoxins," framing meat and dairy, not plant fiber, as the primary dietary endotoxin source.

Travis's own practical diet

Travis describes his own long-term diet (self-described as vegan "for about ten years minus a few winters of heavy cheese eating and the occasional egg-eating") as centered on coconuts, pineapple, dates, raw kale and arugula, potatoes, and coffee, built around minimizing iron, PUFA, and estrogen/growth-hormone-containing foods.

Summary

Vegetarian diets can support health when constructed with awareness of their inherent limitations:

Non-negotiables:

• B12 supplementation (especially for vegans)
• Adequate zinc (supplement if needed)
• Attention to iron status
• Iodine if consuming goitrogens
• Avoiding seed oils and high-PUFA foods

Strongly recommended:

• Including eggs and dairy (lacto-ovo approach)
• Daily raw carrot salad
• Emphasizing fruits, potatoes, and mushrooms over grains and legumes
• Using coconut oil as primary cooking fat
• Minimizing soy and legume consumption

Monitor:

• Thyroid function (temperature, pulse, TSH)
• B12 and homocysteine levels
• Iron, zinc, and calcium status
• Cognitive function over time

For the ambitious vegetarian, eggs, dairy and B12 supplementation are not viewed as compromises, just biological necessities that make the diet sustainable long-term. Those who choose strict veganism should approach it as a temporary practice requiring careful supplementation rather than a permanent dietary framework.