Vegetarianism and Nutrient Deficiencies

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I decided to go vegetarian when I was 18 and vegan soon after, believing I would save the animals, the environment and my health. I thought that my low intake of saturated fat would protect me from heart disease and that my low intake of animal protein and high intake of soy isoflavones would protect me from tooth decay and bone loss. Instead, over the next two years my health took a series of blows: my digestion fell apart; fatigue set in; anxiety took hold; and tooth decay overran my entire mouth—a single visit to the dentist yielded a treatment plan that would take the following year to complete. I was a mess, and I didn’t know why.

When I read Weston Price’s Nutrition and Physical Degeneration about three years after first removing animal products from my diet, I finally understood why my health had fallen apart. I had always associated nutrition with fruits and vegetables. Meat was for protein; milk for calcium; but vitamins were something you got from plant products. Yet the groups that Price studied had a very different idea of nutrition. They valued foods like liver, shellfish and deeply colored butter for their life-promoting qualities. Price used cod liver oil, butter oil and organ meats to supply the fat-soluble vitamins to his patients. These were mostly foods I had never eaten, and the foods with only small amounts of important animal-based nutrients—meat, eggs, and milk—were precisely the ones I had banished from my diet.

Not all vegetarians develop overt health problems in such a short length of time from abandoning animal foods and some—especially those who eat eggs, milk, or occasional fish and shellfish—may maintain good health for decades. A strictly vegetarian diet, however, clearly lacks nutritional qualities that an omnivorous diet possesses. If the people most sensitive to deficiencies of these nutrients suffer the types of problems that I did, those who are less sensitive and not suffering obvious problems may nevertheless fail to achieve optimal health without optimal levels of nutrients from animal sources. This article will discuss those nutrients, their functions and their sources, starting at the beginning of the alphabet with vitamin A.

Vitamin A

The roles of vitamin A in vision, growth, immunity, reproduction and the differentiation of cells and tissues are well known.1 Vitamin A also plays a number of lesser known functions: it is a powerful antioxidant in cell membranes,2,3,4 protects against environmental toxins,5 contributes to the regulation of bone growth,6 protects against asthma and allergies,7,8 prevents the formation of kidney stones,9 and protects against fatty liver disease.10

“Fat-soluble A” originally referred to the ability of butter or egg yolks to support weight gain and prevent mortality in laboratory rats. One of the discoverers of vitamin A, Elmer Verner McCollum, initially attributed the ability of cod liver oil to treat both the eye disease xerophthalmia and the bone disease rickets to its content of this vitamin. Eventually, researchers recognized vitamins A and D as two different vitamins because heating cod liver oil destroyed its ability to cure xerophthalmia but not its ability to cure rickets. Although they would determine over time the fact that the vitamin D content of butter depends on the season and the condition of the cows producing it, the observation that both cod liver oil and butter could cure xerophthalmia but only cod liver oil could cure rickets also contributed to the differentiation of vitamins A and D.11 Vitamin A, then, was originally discovered because of the life-promoting properties of three animal fats.

Research conducted soon after, however, showed that the yellow lipid fraction extracted from yellow-orange vegetables possessed the same activity.12 These vegetables contain betacarotene and other carotenoids that humans and animals can convert into retinol, the functional form of vitamin A found in animal products. In 1949, Hume and Krebs induced vitamin A deficiency in three human subjects; they treated one with retinol and treated the other two with a concentrated dose of beta-carotene dissolved in oil. They concluded that 3.8 units of carotene are required to produce one unit of retinol. A similar experiment conducted in 1974 established a conversion factor of two and several others established conversion factors between two and four.13

In 1967, the United Nations Food and Agriculture Organization (FAO) and World Health Organization (WHO) released a joint recommendation stipulating that six units of beta-carotene and twelve units of other carotenoids with vitamin A activity should be considered equivalent to one unit of retinol, a recommendation they renewed unchanged in 1988. This led H.P. Oomen, the prominent researcher who first highlighted the problem of vitamin A deficiency in the Third World, to write, “The whole procedure of vitamin distribution would be wholly superfluous if adequate carotene were present in the children’s diet.” Oomen believed that just 30 grams per day of dark green leafy vegetables would be sufficient in and of itself to provide adequate vitamin A to undernourished children.14

Yet in the 1990s, this view began to change. In 1994, Suharno and others observed that pregnant Indonesian women were consuming enough carotenes to yield three times the recommended amount of vitamin A based on the WHO’s conversion factor, yet large numbers of them were suffering from marginal vitamin A deficiency. Subsequent intervention studies aimed at Indonesian school children and breastfeeding women in Vietnam found that the conversion factor for carotenes to vitamin A in vegetables was 26 and 28 respectively, and 12 when the carotenes were consumed in fruit. In 2002, the U.S. Institute of Medicine (IOM) established a conversion factor of 12 for beta-carotene, 24 for other carotenoids with vitamin A activity, and two for beta-carotene dissolved in oil. West and others criticized the selective use of studies employed by the IOM, and suggested that beta-carotene from fruits and vegetables in a mixed diet has a conversion factor closer to 21.14

In 2003, Tang and colleagues showed that even the efficiency of beta-carotene dissolved in oil had been grossly overestimated. The researchers gave a concentrated dose of radio-labeled beta-carotene dissolved in oil to 22 adult volunteers and traced its conversion to vitamin A both in the intestine and after intestinal absorption. The mean total conversion rate for the oil-soluble carotene in this experiment was 9.1, and individual rates varied from 2.4 to 20.2.13

Figure 1 compares the vegetables richest in carotenes to the animal foods richest in vitamin A. Eating liver once a week or taking a half teaspoon of high-vitamin cod liver oil per day provides the RDA of 3,000 IU. To obtain the same amount with plant foods, one would have to consume two cups of carrots, one cup of sweet potatoes, or two cups of cooked kale every day. The presumed conversion rate, however, is just an average—by definition, many people will convert carotenes more efficiently than the average and many will convert them less efficiently than the average. People who convert carotenes poorly may suffer from vitamin A deficiency even if they are careful to eat large amounts of carotene-rich foods every day.

Many traditional diets contained much more vitamin A than our government recommends. In 1953, for example, Greenland Inuit subsisting on traditional foods consumed an average of 30,000 IU per day.15 Since researchers are still discovering new roles for vitamin A and still poorly understand many of those already discovered, it would be prudent to assume that the ten-fold increase over the RDA found in traditional diets may have some benefit—providing it is accompanied by a rich array of other fat-soluble vitamins, especially vitamin D, which protects against its toxicity.16

It would be virtually impossible to obtain this amount of vitamin A from plant foods without either juicing or using supplemental beta-carotene. Even these methods may be insufficient, however, since larger doses of carotenes are converted less efficiently than smaller ones.13 Massive doses of beta-carotene, moreover, increase levels of oxidative stress and stimulate the production of enzymes that degrade true vitamin A. By inducing a cellular vitamin A deficiency, large doses of beta-carotene cause cancerous changes in lung tissue even worse than those seen from cigarette smoking. For this reason, high-dose beta-carotene supplementation led to increases in cancer mortality and total mortality in two human trials.17 Although no studies have demonstrated this type of harm from juicing, carrot juice has the potential to raise blood levels of beta-carotene to the extremely high levels found in the aforementioned trials and large amounts of it may theoretically pose a risk.18 By contrast, the amount of beta-carotene found in a diet rich in vegetables protects against oxidative stress and cancer.17

The best plant source of vitamin A is red palm oil. Its oily matrix makes its carotenes more readily converted to vitamin A and its high content of vitamin E and low content of the polyunsaturated linoleic acid further augment the convertibility of its carotenes and also protect against their potentially destructive effects. It is pure speculation, however, to suppose palm oil can be considered functionally equivalent to vitamin A-rich foods such as liver and liver oils. Vegetarians should use red palm oil, but those who are willing to include liver or liver oils in their diet would be better off for doing so.

Vitamin D

Vitamin D is best known for its relation to calcium metabolism. By supporting the absorption of calcium from food, it prevents and cures the childhood bone disease rickets and its adult counterpart osteomalacia. It also protects against tetany, convulsions and heart failure in newborns, helps prevent osteoporosis in the elderly, prevents the development of type 1 diabetes, and is believed by some researchers to have additional roles in protecting against cancer, heart disease, high blood pressure, obesity, arthritis, multiple sclerosis and various other diseases.19

Vitamin D was originally associated with cod liver oil and exposure to ultraviolet light. It is found in the highest amounts in fish livers, the flesh of fatty fish, and the blood of land animals; and in smaller amounts in butter and lard from animals raised with plenty of exposure to sunshine. Skin contains a precursor to cholesterol called 7-dehydrocholesterol that converts to vitamin D upon exposure to sunlight in the UV-B range, which is available year-round in the tropics but absent during an increasing portion of the year with increasing distance from the equator.19

While humans and animals synthesize vitamin D3, a second form of the vitamin called vitamin D2 is found in some vegetarian foods, especially mushrooms that have been exposed to ultraviolet light. Although the relative safety and efficacy of the two forms is still controversial, vitamin D2 appears to be five to ten times less effective at supporting long-term nutritional status.19

The RDA for vitamin D is 200 IU for infants and adults through the age of 50, 400 IU for adults between the ages of 50 and 70, and 600 IU for adults over the age of 70. Evidence strongly suggests, however, that the true requirement is far higher. Supplements of 2,000 IU per day in infants under the age of one nearly obliterate the life-long risk of type 1 diabetes while supplements of 800 IU or higher are required to reduce the risk of fracture in the elderly. Nebraskans need to supplement with 1,000 IU per day during the coldest six months of the year to achieve blood levels that maximize calcium absorption and with almost 5,000 IU per day during the same period of time to achieve blood levels similar to those achieved in sun-rich living conditions without supplementation. These amounts of vitamin D should only be consumed in the context of a diet rich in vitamin A and vitamin K2 for maximal efficacy and safety.19

Figure 2 shows the distribution of vitamin D in foods. The easiest way to obtain dietary vitamin D is to eat fatty fish or supplement with high-vitamin cod liver oil. Obscure mushroom products can provide large amounts of vitamin D2, but the safety and efficacy of this form is questionable. For most people living outside 35 degrees latitude from the equator, animal foods supply needed vitamin D in the diet.

Vitamin K2

Vitamin K is the king of the fat-soluble vitamins. Vitamins A and D cooperate to tell cells which proteins to make; vitamin K is responsible for activating these proteins and making them functional by conferring upon them the ability to bind calcium. In addition to its classically understood role in blood clotting, vitamin K is necessary for the deposition and organization of calcium salts in bones and teeth; the protection of blood vessels, kidneys and other soft tissues from abnormal calcification; and the synthesis of important lipids involved in brain metabolism.20

Vitamin K comes in two forms: K1 and K2. Vitamin K1 is found in green plants, while vitamin K2 is found in animal fats and fermented foods. Vitamin K1 is preferentially used for the activation of blood clotting factors, while vitamin K2 is preferentially used for all of vitamin K’s other functions. The two K vitamins are therefore not interchangeable. The clearest demonstration of this is the fact that only vitamin K2 is associated with a reduced risk of heart disease. In the Rotterdam Study, subjects consumed nearly ten times more K1 than K2; a high intake of K2 reduced the risk of severe arterial calcification by 52 percent and reduced heart disease mortality by 57 percent, while a high intake of K1 had no effect.21

Figure 3 shows vitamin K2 contents of selected foods. Animal products dominate the list—especially goose liver and goose meat, cheeses and egg yolks—but natto, a strong-tasting fermented soy food common in Eastern Japan, actually has the highest amount. Natto contains a specific form of vitamin K2 called menaquinone (MK-7), rather than MK-4, the form found in animal products; the relative efficacy of these two forms is currently unknown. It is therefore possible for a vegetarian diet to be rich in vitamin K2. Most vegetarians do not consume natto, however, and most vitamin K2 consumed by participants in the Rotterdam Study came from meat, eggs and cheese.

Vitamin B12

Vitamin B12 is required for the synthesis of new DNA, the degradation of certain amino acids, the production of energy, the formation of red blood cells and the formation of myelin, the sheath that insulates neurons. Its deficiency occurs in four stages, beginning with declining blood levels of the vitamin (stage I), progressing to low cellular concentrations of the vitamin (stage II), an increased blood level of homocysteine and a decreased rate of DNA synthesis (stage III), and finally, pernicious anemia (stage IV). Irreversible nervous system degeneration also occurs in cases of severe deficiency.24

Pernicious anemia is a condition in which red blood cells are immature, oversized and cannot function properly. Because DNA synthesis is compromised, the cells do not divide as they should. The disease was first identified in 1824 and was considered incurably fatal until the 1930s when physicians discovered that it could be treated with liver. Soon after, they found that stomach juice could be used in conjunction with the liver to enhance its effect.25

Conventional nutritional wisdom considers vitamin B12 as the one vitamin found exclusively in animal products. There are some bacteria in the small intestine that synthesize absorbable B12, but their presence is unreliable and they face competition from bacteria that synthesize inactive analogues that compete with B12 for absorption.26 Most supplements supply cyanocobalamin, in which each molecule of B12 is attached to a molecule of cyanide. Since vitamin B12 detoxifies cyanide by binding it and causing its excretion in the urine, this form might have very poor bioavailability in many people. Cyanide can also be detoxified in the liver by the enzyme rhodanese or by the amino acid cysteine,27 so people with a low activity of this enzyme or a low intake of animal protein to supply the cysteine might be especially unable to derive any benefit from cyanocobalamin. Thus, even vegetarians who supplement with standard B12 supplements could be at risk for deficiency. Those needing B12 supplements should take methylcobalamin, dibencozide or hydroxycobalamin, forms that are more easily utilized by the body; additionally, some people with certain genetic defects or heavy metal toxicity may require methylcobalamin specifically.

The role of vitamin B12 in DNA synthesis and red blood cell production is primarily to recycle folate. A high intake of folate, however, can compensate for insufficient folate recycling. Unfortunately, this means that a high-folate diet can forestall the development of anemia, which is easily detectable with a simple blood test, while potentially irreversible nervous system degeneration progresses without warning. Vegetarians who consume large amounts of folate-rich green leafy vegetables could therefore be at risk for a form of vitamin B12 deficiency that is not considered severe until it is too late.24

A recent study using a biochemical blood test for B12 deficiency—a test that is not vulnerable to the confounding effect of a high-folate diet—found that 16 percent of the elderly, 43 percent of lacto-ovo vegetarians and 64 percent of vegans are deficient in B12.28 Since deficiency can take decades to fully develop, the proportions of vegans and vegetarians who develop deficiency over time if they stick with the diet is probably close to 100 percent.

Some vegetarians and vegans maintain that these diets must be raw in order to be truly healthy. But raw foodists are no better off. The only large-scale study of raw foodists to date examined the B12 status of over 200 men and women. Although 58 percent of the subjects consumed some meat and fish and only 21 percent were lacto-ovo-vegetarian and only 21 percent were vegan, a full 97 percent of all foods consumed were plant products. Those eating a mixed diet were thus eating very little animal food. Nevertheless, vegetarians were 3.1 times as likely and vegans were 5.4 times as likely to have deficient blood levels of B12. Twelve percent of the subjects, all of whom were vegans, had stage IV B12 deficiency.29 Even though the average length of time the subjects had followed the raw food diet was only 3.6 years, over half the vegans were developing pernicious anemia; if many of them were eating folate-rich diets, the proportion of vegans developing irreversible nervous system degeneration might have been even higher than the proportion the study suggested were suffering from severe deficiency. Clearly, animal foods must be used if even in small amounts to prevent the worst form of B12 deficiency from destroying a person’s mental and physical health.

Vitamin B6

Vitamin B6 contributes to myriad functions within the body. It is necessary for the production of histamine, which is involved in inflammation in most of the body but is essential to alertness in the brain; the production of dopamine, which is a precursor to adrenaline and noradrenaline in the adrenals, a precursor to melanin in pigmented tissues, and is involved in memory, attention, and problem-solving in the brain; the storage of carbohydrate as glycogen; the production of the elongated versions of essential fatty acids such as arachidonic acid (AA) and docosohexaenoic acid (DHA); the synthesis of cysteine, the precursor to glutathione, which is the master antioxidant of the cell; the synthesis of glycine, which is involved in detoxification in the liver; the synthesis of heme, which carries oxygen throughout the body in hemoglobin and is a component of drug- and steroid-metabolizing, energy-producing, and antioxidant enzymes; the synthesis of carnitine, which helps burn fat for energy; and the synthesis of taurine, which plays important roles in the brain and eye and assists the digestion of fat and assimilation of fat-soluble vitamins in the intestines. The requirement for B6 is directly proportional to the intake of protein and increases with the use of oral contraceptives and under conditions of hyperthyroidism, liver disease, trauma and stress.24

Vitamin B6 occurs in three forms: pyridoxine, pyridoxamine and pyridoxal. Plant foods contain pyridoxine, while animal foods contain a mix of pyridoxal and pyridoxamine. Most reactions within the human body require pyridoxal but some require pyridoxamine. Pyridoxine, by contrast, plays no role in the body whatsoever but can be converted into the other two forms in the liver using vitamin B2.24

The plant form of vitamin B6 has three strikes against it, making it inferior to the form found in animal foods: its conversion to the active form depends on B2 status, and vitamin B2 levels tend to be higher in animal foods; most plant foods simply contain much less B6 than most animal foods; and most plant foods contain much of their B6 bound up with sugars that make it difficult or impossible to absorb. Figure 4 shows some of the foods richest in vitamin B2. Supplementation with baker’s yeast and the use of enriched white flour can boost B2 intake, but the level found in natural plant foods is much lower compared to the levels in many animal foods. Figure 5 compares the plant foods richest in B6 to the animal foods richest in the vitamin. Tuna and liver are the best sources, and, in general, animal foods contain twice as much as plant foods. Figure 6 shows the proportion of pyridoxine bound to sugars in various plant foods, which ranges from zero percent in almonds to 82 percent in cauliflower.

The sugars that bind to pyridoxine can be broken down by microbial enzymes and the mammalian intestine appears to produce a limited quantity of the enzyme as well.30 Studies conducted with humans suggest that the sugar-bound form has at most fifty percent bioavailability and at worst, none at all. One study conducted in men with a purified form of glucose-bound pyridoxine, for example, examined the urinary output of a B6 breakdown product and found that roughly half of the pyridoxine was absorbed. A more realistic study conducted in women using whole plant foods, however, examined not only the urinary output of breakdown products, but also the concentration of the active form in red blood cells and the activity of enzymes dependent on it. This study suggested that the portion of plant-based B6 in the diets bound to sugars had no activity at all.30

Heating destroys vitamin B6. The effect is rather mild, leading to only five percent loss in scrambled eggs, ten percent loss after heating of milk for ten minutes and 45 percent loss after heating milk for one hour.31 The true effect on the biological activity of B6, however, is much greater because heat-damaged B6 can interfere with true B6 and when fed in purified form can actually accelerate the symptoms of deficiency.32 Cooking most animal foods leads to a 25-30 percent decrease in activity while cooking soybeans leads to a 40 percent decrease in activity.33 Many plant foods require more extensive cooking than animal products, which could further decrease the yield of active B6 in vegetarian diets.

One striking comparison between lactating Nepalese vegetarian women and their American omnivore counterparts illustrates the low bioavailability of B6 from plant foods. The Nepalese women in this comparison were consuming twelve percent more B6 but had 35 percent lower serum levels of the active form after three months of lactation and 77 percent lower levels after six months. Their breast milk had the same amount of B6 as that of American women, but a large proportion of it was glucose-bound pyridoxine. Despite the fact that the Nepalese vegetarians were consuming more B6 in the diet and had equivalent levels in their breast milk, their infants had 83 percent lower levels of the active form at four months and 87 percent lower levels at six months.33

Vegetarians should select plant foods that have the least amount of their pyridoxine bound up in sugar complexes. Bananas are an excellent source because the sugar-bound form is low, their total content is comparable to many meats, and they are typically eaten raw. Most plant foods are relatively poor sources, however, and B6 intake would be much higher on a mixed diet including muscle meats, seafood and organ meats.


Zinc is a cofactor for literally hundreds of enzymes. It is an essential structural component of all nuclear hormone receptors as well as some hormones themselves, such as insulin. It acts as an antioxidant in cell membranes by displacing pro-oxidant metals like iron and mercury and is also a cofactor for the antioxidant enzyme superoxide dismutase. A small sample of its biological functions include cell and tissue growth, cell replication, bone formation, skin integrity, immunity, digestion, glucose tolerance, maintenance of a high basal metabolic rate and taste acuity.24

Figure 7 shows the distribution of zinc in foods. Although present in grains, legumes, fruits and vegetables, it is found in much lower amounts compared to animal foods and is much less bioavailable. Oysters contain between four and twenty times as much zinc as beef, while beef contains two to four times as much as other meats, four times as much as eggs, ten times as much as milk and four or more times as much as virtually all plant products. Moreover, zinc absorption is inhibited by plant compounds such as phytate, oxalate, polyphenols and fiber, and enhanced by compounds present in meat. Its absorption is greater than 50 percent in the absence of inhibitors but less than 15 percent in the context of a high-phytate meal.34 While a well planned vegetarian diet may escape overt zinc deficiency, it would be virtually impossible to maintain a truly robust zinc status without the inclusion of animal foods.

Essential Fatty Acids

The essential fatty acids as a group are a double-edged sword. On the one hand, small amounts of them are required for the synthesis of various biologically important hormones and hormone-like molecules; on the other hand, they are highly unsaturated and their multiple double-bonds are highly vulnerable to oxidation. Even fresh, non-oxidized DHA, eicosapentaenoic acid (EPA), and omega-3-rich perilla oil increase oxidative stress markers when fed to rats.35

Since it is the elongated forms of the essential fatty acids that are especially important—including AA, DHA, EPA, and dihomo-gammalinolenic acid (DGLA)—and since the conversion of precursors in plant oils is inefficient, it makes sense to consume small amounts of these fatty acids preformed from animal foods so we can reduce the total amount of polyunsaturated fatty acids (PUFA) we need to obtain them. Moreover, some people with particularly low levels of the enzymes that make these conversions may be vulnerable to an actual deficiency of the elongated forms even while consuming plenty of pro-oxidant PUFA from plant oils.

Vegetarians have 30 percent lower levels of EPA and DHA than omnivores, while vegans have over 50 percent lower EPA and almost 60 percent lower DHA. By contrast, vegetarians have 10 percent higher levels and vegans have over twenty percent higher levels of linoleic acid, the omega-6 precursor fatty acid.36 If this situation is characteristic of omnivores eating a standard diet high in polyunsaturated oils, we can imagine what the comparison might look like between vegans and vegetarians with a population that avoids PUFA-rich vegetable oils and consumes elongated EFA-rich liver, egg yolks, and small amounts of cod liver oil. The latter diet allows no deficiency of these fatty acids but provides a minimum of total PUFA, and therefore a minimum of oxidative stress and aging-related damage.

Conditionally Essential Amino Acids

There are a number of amino acids and related compounds that are not technically essential, but are useful in the diet, possibly essential under certain conditions, and found exclusively or almost exclusively in animal products. These include carnitine, taurine, creatine and carnosine.37

Carnitine shuttles fatty acids into the mitochondria, the so-called “power house of the cell,” to be burned for energy, and recycles pantothenic acid, an important B vitamin. Omnivorous diets provide between two and twelve times as much carnitine from meat as the body can produce by endogenous synthesis. Moreover, its synthesis requires vitamins C, B12, and B6. Vegetarian diets tend to be rich in vitamin C but poor in these B vitamins, so synthesis could be compromised. A reduced rate of synthesis and little or no intake could lead to an impaired ability to utilize fat for energy and a lower pantothenic acid status.37

Taurine and glycine are both incorporated into bile acids, but those incorporating taurine are absorbable much further down in the intestines and are therefore much more effective at maximizing the absorption of fat and fat-soluble vitamins. Taurine is also involved in preventing drug-induced cardiac arrhythmia, maintaining the electrical activity of the retina and supporting the development of the brain. The developing brain contains three to four times as high a concentration of taurine as the adult brain, so taurine is particularly important for nursing infants. It is found almost exclusively in animal products and its endogenous synthesis requires vitamin B6. The serum concentrations of vegans and infants nursing from them are lower than that of their omnivore counterparts, which may compromise the development of the nervous system.37

Creatine is necessary for the maintenance of the cellular energy supply, especially during bursts of physical activity, and its supplementation is therefore useful for athletic performance. The endogenous synthesis is one to two grams per day while meat provides one gram per serving, so meat-inclusive diets make a substantial contribution to total creatine status. While vegetarians may not be at risk for an actual creatine defi-ciency, the additional creatine from meat could be helpful in boosting physical performance.37

Carnosine functions as a neurotransmitter and is a powerful inhibitor of a process called glycation, whereby sugars and PUFA bind up with proteins and produce advanced glycation end products (AGEs), which are believed to contribute to the adverse effects of aging. It is found exclusively in animal products, which may be one reason why vegetarians and vegans have higher levels of AGEs than omnivores.37,38


Most people make enough cholesterol to fulfill their body’s needs; cholesterol is therefore not considered an essential nutrient. There are, however, millions of people with genetic defects in cholesterol synthesis for whom dietary cholesterol is likely an essential nutrient.

Smith-Lemli-Opitz Syndrome (SLOS) is the best-understood cholesterol deficiency syndrome. It results from a genetic defect in the enzyme that converts 7-dehydrocholesterol (a common precursor of vitamin D and cholesterol) to cholesterol. Most commonly, it results in spontaneous abortion within the first sixteen weeks of gestation so it shows up in only one in 60,000 live births. Children who are born with the defect may suffer from mental retardation, autism, facial and skeletal malformations, visual dysfunctions and failure to thrive. The current treatment is dietary cholesterol.39

Because both parents must supply a defective copy of the gene in order for SLOS to manifest, and because most pregnancies that would result in an SLOS birth are spontaneously terminated, the number of people who carry a single copy of the defective gene is far higher than the number of people with the full-blown syndrome. One in a hundred North American Caucasians and as many as one in fifty or even one in thirty Central Europeans carry the defective gene. These people, called “SLOS carriers,” have a decreased rate of cholesterol synthesis, but still synthesize enough to escape the severe risks and abnormalities that characterize clinical SLOS.40

One small study has examined possible mental health effects in 105 SLOS carriers. Carriers were more than three times as likely to have attempted suicide as those who do not carry the gene, and the methods of committing suicide were more violent. Unfortunately, the study was not statistically powerful enough to conclusively determine whether or not these associations were due to chance, but it was powerful enough to show a conclusive relationship between carrying the gene and having biological relatives who attempted suicide. Carriers were more than four times as likely as controls to have at least one biological relative and almost six times as likely to have a first-degree relative who attempted or committed suicide.41

It may be the case, then, that dietary cholesterol is an essential nutrient for one to three percent of the population. There may also be additional genetic defects or variations in cholesterol synthesis that may make dietary cholesterol essential. For these groups, animal foods are absolutely necessary.

The Essentiality of Animal Foods

When Weston Price traveled to the South Sea Islands of the Pacific, he hoped to find “plants or fruits which together, without the use of animal products, were capable of providing all of the requirements of the body for growth and for maintenance of good health and a high state of physical efficiency.” He was disappointed. On the island of Viti Levu, he instead found inland-dwelling groups relying largely on plant products who found it so essential to consume shellfish at least once every few months that they would trade plant foods from the mountains for shellfish with coast-dwelling groups even when these groups were at war with each other. Shellfish are especially dense in animal-based nutrients. One serving of clams per month provides the same amount of vitamin B12 as two servings of salmon per week. One serving of oysters per week likewise provides the same amount of zinc as a quarter pound of beef per day. People who wish to minimize their intake of animal products would do best to consume small amounts of shellfish to obtain these nutrients. For those who do not wish to eat shellfish, the requirement for animal products might be much higher.

Price’s research led him to the following conclusion about vegetarianism: “As yet, I have not found a single group of primitive racial stock which was building and maintaining excellent bodies by living entirely on plant foods. I have found in many parts of the world most devout representatives of modern ethical systems advocating restriction of foods to the vegetable products. In every instance where the groups involved had been long under this teaching, I found evidence of degeneration in the form of abnormal dental arches to an extent very much higher than in the primitive groups who were not under this influence.”

Thus, we can conclude from Dr Price’s studies and a large body of subsequent research that animal foods should be used throughout childhood development, especially those animal foods that are richest in vitamins and minerals, such as liver, shellfish, egg yolks, bone broths, and high-quality dairy products. Depending on their individual constitutions, adults may have varying needs for animal products and those who object to the use of meat should either consume shellfish on a weekly or monthly basis, or high-quality dairy and egg products on a daily basis. Additionally, red palm oil and bananas would respectively be useful sources of carotenoids and vitamin B6.

Many people may last a long time on a diet that does not contain optimal levels of animal products, while others like myself may develop health problems very quickly. Given all the nutrients that are so much more easily obtained from animal products, it should not be surprising that some people adopting a vegetarian or vegan diet may develop deficiencies very quickly. Each person has to pay careful attention to his or her own body and give it the nutrients it needs—and for many people this will mean giving up on the myths of vegetarianism and consuming the animal products we require by nature.


Figure 1. Vitamin A Yield of Plant and Animal Foods

All values are derived from the USDA National Nutrient Database for Standard Release 17, except cod liver oil, which is derived from the information provided by commercial manufacturers. All values of vitamin A yield are expressed per 100 grams of food, except cod liver oil, which is expressed per teaspoon. Vitamin A yield values follow West et al. (2002) in assuming that the retinol activity equivalent (RAE) figures for vegetables overestimate the true conversion by 75 percent. These values, however, represent an average conversion factor from a mixed diet and therefore do not represent differences in bioavailability between specific foods—the carotenoids in carrots, for example, are five times more bioavailable than those in spinach.

Plant Foods Vitamin A Yield IU per 100g Animal Foods Vitamin A IU per 100g
Sweet Potatoes 1,500 Turkey Giblets 35,800
Carrots 1,145 Beef Liver 25,800
Kale 1,295 High-Vitamin Cod Liver Oil (1 tsp) 5,750
Spinach 997 Commercial Eggs 570
Collard Greens 770 Commercial Butter 330

Figure 2. Vitamin D Content of Selected Foods

These figures are obtained from Reinhold Vieth’s chapter in the second edition of the textbook, Vitamin D, edited by Feldman and others, except cod liver oil, which is taken from information provided by commercial manufacturers, and pork or bovine blood, which is estimated based on blood concentrations expected in a sun-rich environment. All values are assumed to be vitamin D3 unless otherwise specified.

Food (100g unless otherwise specified) Vitamin D (IU) Food (100g unless otherwise specified) Vitamin D (IU)
Dried Woody Ear or Silver Ear Fungus 16,000 (D2) Grunt and Rainbow Trout 600
Anglerfish Liver 4,400 Eel 200 – 560
Summer Pork or Bovine Blood (1 cup) 4,000 Cultured Red Sea Bream 520
High-Vitamin Cod Liver Oil (1 tbsp) 3,450 Mackerel 345 – 440
Indo-Pacific Marlin 1,400 Salmon 360
Chum Salmon 1,300 Canned Sardines 270
Standard Cod Liver Oil (1 tbsp.) 1,200 Chicken Egg 120
Herring 1,100 Common Mushroom 100 (D2)
Cultured Bastard Halibut 720 Pork Liver 50
Fatty Bluefin Tuna 720 Unfortified Summer Milk (1 liter) 40
Duck Egg 720 Beef Liver 30
Dried Shitake Mushroom 640 (D2) Pork 28

Figure 3. Vitamin K2 Content of Selected Foods

Values taken from references 22 and 23. MK-4 is the type of vitamin K2 synthesized by animal bodies from vitamin K1. Whether it has special value apart from other forms of vitamin K2 has yet to be determined.

Food Vitamin K2 (mcg/100g) Percentage MK-4 Food Vitamin K2 (mcg/100g) Percentage MK-4
Natto 1103.4 0% MK-4 Chicken Liver 14.1 100% MK-4
Goose Liver Paste 369.0 100% MK-4 Salami 9.0 100% MK-4
Hard Cheeses 76.3 6% MK-4 Chicken Breast 8.9 100% MK-4
Soft Cheeses 56.5 6.5% MK-4 Chicken Leg 8.5 100% MK-4
Egg Yolk (Netherlands) 32.1 98% MK-4 Ground Beef (Medium Fat) 8.1 100% MK-4
Goose Leg 31.0 100% MK-4 Bacon 5.6 100% MK-4
Curd Cheeses 24.8 1.6% MK-4 Calf Liver 5.0 100% MK-4
Egg Yolk (US) 15.5 100% MK-4 Sauerkraut 4.8 8% MK-4
Butter 15.0 100% MK-4 Salmon 0.5 100% MK-4
Mackerel 0.4 100% MK-4

Figure 4. Vitamin B2 Content of Selected Foods

Vitamin B2 is necessary for the conversion of pyridoxine found in plant foods to pyridoxal, the active form of B6, which is found preformed in animal foods. Data from the USDA National Nutrient Database for Standard Release 17.

Food Riboflavin (mg/100g) Food Riboflavin (mg/100g)
Baker’s Yeast 5.47 Pork Ribs 0.38
Beef Liver 3.42 Veal 0.35
Chicken Liver 1.99 Boiled Mushrooms 0.30
Pork Liver Sausage 1.53 Boiled Beet Greens 0.29
Turkey Giblets 1.50 Boiled Soy Beans 0.28
Chicken Giblets 1.05 Boiled Spinach 0.24
Fried Shrimp 0.55 Skim Milk Yogurt 0.23
Enriched White Flour 0.51 Ricotta Cheese 0.20
Eggs 0.48 Milk 0.18
Roasted Duck 0.47 Salmon 0.17
Clams 0.43 Tomato Paste 0.15

Figure 5. Vitamin B6 Content of Selected Foods

The richest animal foods tend to be about twice as rich as the richest plant foods. Although not shown in the table, the plant foods contain pyridoxine rather than pyridoxal and pyridoxamine, which must be converted to the active forms in the liver, and contain it in varying amounts bound up to sugars, making it unavailable. Data taken from the USDA National Nutrient Database for Standard Release 17.

Plant Foods B6 mcg/100g Animal Foods B6 mcg/100g
Buckwheat Flour 582 Fresh Tuna (Dry Cooked) 1,038
Roasted Chestnuts 497 Beef Liver (Pan Fried) 1,027
Canned Chickpeas 473 Beef Top Sirloin (Broiled) 631
Hash Browns 472 Pork Chops (Bone In) 513
Banana (Raw) 367 Pacific Cod (Dry Cooked) 462
Whole Wheat Flour 340 Roasted Turkey 460
Sweet Red Peppers 291 Roasted Ham 449
Brussels Sprouts 289 Halibut (Dry-Cooked) 435
Spinach (Boiled) 242 Rainbow Trout (Dry-Cooked) 435
Soy Beans (Boiled) 234 Chicken Breast With Skin 430
Pinto Beans 229 Swordfish (Dry-Cooked) 381
Prune Juice 218 Haddock (Dry Cooked) 346
Carrot Juice (Canned) 217 Pacific Rockfish (Dry Cooked) 270
Tomato Paste 216 Roasted Duck 250

Figure 6. Percentage of Vitamin B6 in Plant Foods that Exists as Pyridoxine Glucoside

Pyridoxine glucoside is the sugar-bound form that has little if any bioavailability in humans. Data taken from reference 33.

Food % Pyridoxine Glucoside Food % Pyridoxine Glucoside
Cauliflower, frozen 63-82 Peanut butter 18
Carrots 51-75 Whole wheat bread 17
Orange juice, fresh 37-69 Bananas 3-16
Soy beans, cooked 57-67 Peas, frozen 15
Broccoli, frozen 65 Apricots, dried 14
Raisins 65 Rice (white), cooked 14
Green beans, canned 28-58 Whole wheat flour 11
Broccoli, raw 35-57 Green beans, raw 10
Orange juice, concentrate 47-53 Corn, frozen 6
Cabbage 46 White bread 6
Navy beans, cooked 42 Fortified wheat flakes cereal 5
Wheat bran 37-36 Cauliflower, raw 5
Spinach 35 Rice bran 4
Tomato juice 32 Filberts, raw 4
Shredded wheat cereal 28-31 Avocados, fresh 3
Dark rye bread 23 Walnuts 1
Peaches, canned 21 Almonds, raw 0

Figure 7. Zinc Content of Selected Foods

The zinc content of animal foods is not only much more bioavailable than that of plant foods, but also much higher. Data taken from reference 24.

Animal Foods Zinc (mg/100g) Plant Foods Zinc (mg/100g)
Oysters 17.0-91.0 Legumes (Cooked) 0.6-1.0
Crabmeat 3.8 – 4.3 Rice and Pasta (Cooked) 0.3-0.6
Shrimp 1.1 Whole Wheat Bread 1.0
Tuna 0.5 – 0.8 White Bread 0.6-0.8
Liver 3.1 – 3.9 Vegetables (All) 0.1-0.7
Chicken 1.0 – 2.0 Fruits (All) <0.1
Ground Beef 3.9 – 4.1
Veal 3.1 – 3.2
Pork 1.6 – 2.1
Eggs 1.1
Milk 0.4
Cheeses 2.8 – 3.2


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This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Spring 2008.

20 Responses to Vegetarianism and Nutrient Deficiencies

  1. Brandy Gunderson says:

    It was interesting reading your antecdotal evidence in the first paragraph of this article. For me, I had the opposite effects. After having started a vegetarian diet, I lost 15 pounds, had a ton more energy, more mental clarity, better bowel habits, less indigestion, less depression, and an overall general feeling of wellness. I admit, I do track my intake of nutrients to assure proper complete protein, amino acids, and vitamin consumption, and I also contribute much of the benefits I mentioned to the increase in my diet to 30 – 40 grams of fiber daily. But, I still think that it would seem there is no black or white, one-size-fits-all approach to diet or nutrition. I assure you that my serum vitamin levels, hemoglobin and hematocrit, and hormones are well within normal limits. So, it may just be that a vegetarian diet is not as dreadful to all humans as you might lead others to believe.?!

  2. Daniel Sanelli says:

    What were you eating before?

    What was your diet like before you went vegetarian? And how long have you been eating that way? I had similar improvement when I went vegetarian because my diet was really crappy before that. But after years on that diet I began to notice the effects of deficiency in my almost vegan diet. When I returned to a balanced, healthy, mostly plant based with healthy animal protein, that’s when I felt the best.

    But you’re correct that some people can do better on a vegetarian diet than others, so maybe that is the case with you. I think the key is to find the diet that is best for the individual – optimal health for each individual. At least that is what my studies have shown me.

  3. jennifer says:

    Vegetarian diet is not as dreadful to all humans as you lead others to believe????
    Hi there as a holistic lifestyle coach and personal trainer for 25 years, I have seen nothing come of eating grains/vegan based diets. I also work for a major organic grocery store chain and it is more prolific there as well!!

    I have never seen a more lethargic unhealthy bunch of people. They just don’t look good. Vitality is awash and they have no happy moods what so ever. “They” being the vegetarians, though I am over simplifying this matter, it has been more often than not, that health problems have abounded due to the low fat, high grain, extreme vegan diet they consume. I am forty and I have been in the fitness idustry since I was 18 and it has only gotten worse!!

    Not only am I 40, but I look darn good for having three girls under 8!!!

    😉 🙂

  4. Charles Fraser says:

    meat-eaters are known to be more likely to have a vitamin B12 deficiency – this has been known since 1959!!(
    “All of the Vitamin B12 in the world ultimately comes from bacteria. Neither plants nor animals can synthesize it. But plants can be contaminated with B12 when they come in contact with soil bacteria that produce it. Animal foods are rich in B12 only because animals eat foods that are contaminated with it or because bacteria living in an animal’s intestines make it.”
    – From “The Vegetarian Way: Total Health for You and Your Family” -1996, Virginia Messina, MPH, RD, & Mark Messina, PhD p. 102

    ‘Stop Building Disease’ – Tom Lodi MD

    A whole lifetime’s requirement of B12 add up to a 40 milligram speck of red crystals, about one-seventh the size of an average tablet of aspirin!

    A B12 deficiency can be caused by antibiotics (from the drugs themselves and contained in milk and meat), alcohol (alcohol damages the liver, so drinkers need more B12) and smoking (and all high temp cooked food is smoky) and stress also raises B12 needs).

    The author does not believe that a vitamin B12 deficiency is more widespread in vegans or vegetarians – this is probably just another marketing lie! In fact, many so-called studies ‘showing vegans deficient’ have to be carefully studied themselves – many of them do not prove vegans to be deficient at all! In fact, contrary to meat and dairy industry propaganda, meat-eaters are known to be more likely to have a vitamin B12 deficiency – this has been known since 1959!!

    this is independent to the studies from hiprocates, and bot say that meat eaters are more likely to be deficient

    The author contends that animal and dairy produce is a poor source of Vitamin B12 since they are normally cooked and thereore the vitamin is contained in nutrient-deranged foodstuffs which will inevitably destroy the usability of the vitamin.

  5. Zusa says:

    Listening to the lecture given by Dr. Gonzalez at the 2010 conference, (part 3, I think, but maybe starts in part 2), my eyes were opened even more to bio-individuality and especially in regards to metabolic types (and not just anyone’s version of this). His speech was so fascinating and I will never see diet and nutrition in the same way! If I remember correctly, he said we lose health in two ways — one is not eating whole, pure foods and the other is eating incorrectly for our type.

  6. t0mmy says:

    I can’t imagine what kind of mess you were eating when you went vegetarian, but at a much younger age when I went vegan I became much healthier and actually got some meat on my bones (I was very skinny before being vegan). I don’t need to see a dentist because my teeth are great and all it took was a more natural diet (lots of fresh veggies).

    The diet of GMO soybeans probably didn’t do much good for you. I’d suggest trying it again but add in plenty of nuts, seeds, legumes, fruits and veggies… you know, the stuff that has a wealth of the nutrients you mysteriously left off your comparison list 😀

  7. michael says:

    That’s great that you feel more energetic and everything, but I just want to ask all the vegetarians: why would you want to restrict yourself from eating foods that are more bioavailable, have higher concentrations of important vitamins and minerals and are what humans have been eating for thousands of years, before our modern commercial food took over?

  8. Joe says:

    I think the thing with vegetarianism is that it just takes a lot of work and attention for something that should be so basic as eating. It seems so complex having to track nutrients all the time, discover the best combinations for this and that, and so on. From reading this site and looking into what Weston A. Price found, great health ultimately ends up being a matter of nutrient density. As demonstrated in this article, it takes a LOT of vegetables to equal the nutrient density of a much smaller animal product (like liver and vitamin A), not even considering that the animal product likely has proper fat and cholesterol attached for absorption purposes. Despite being expensive to buy all those vegetables, the roulette of how much nutrients are actually IN the vegetable (mainly an issue due to poor growing practices, transport, artificial ripening, and many other factors), and that many vegetables are unavailable to all people at all times, and it just becomes too much. People could just incorporate some animal product into their diet, a cheaper, more effective route than supplementation.

    Which leads me to the crazed B12 person Charles Fraser. I have no idea where you get your information from, but you couldn’t be more wrong about any of it. Just taken from the Wikipedia page on B12 deficiency, of which I’m removing the citations to academic journals and vegan groups (yes, vegan groups are saying the following):

    “The Vegan Society and other leading researchers in vegan nutrition have concluded that there are no known sources of naturally occurring vitamin B12 in plants that will satisfy even the minimum B12 nutritional requirements of human beings. The National Institutes of Health in the United States state clearly that “Vitamin B12 is generally not present in plant foods.” Vitamin B12 is found in small quantities in certain algae such as nori, yet there is no evidence that the form of B12 naturally present in these plant substances is bioavailable to human beings. In fact, at least one study suggests that nori is not a source of bioavailable B12 for human beings. Other claimed sources of B12 that have been shown to be inadequate or unreliable through direct studies of vegans include barley grass and human intestinal bacteria (human colonic bacteria produce B12, but it cannot be absorbed from the colon). The present scientific consensus is that any B12 that may be present in specific plant foods is likely to be unavailable for the purposes of human nutrition, at least in part because these foods may contain structural analogues to B12 that compete with B12 in the human body and inhibit B12 metabolism. While vegetarians often get enough B12 through consuming dairy products, the existing scientific evidence suggests that vegans will almost certainly experience a B12 deficiency unless they consume B12-containing dietary supplements or B12-fortified foods.”

    Again, vegan groups agree with this statement.

    What magical red crystals are you even talking about? A lifetime supply of B12 in 40 mg?

    B12 is needed in the diet. Meat eaters are certainly not going to be more likely to be B12 deficient if vegans aren’t even eating it. I don’t know what branch of logic that even follows. Anyways, deficiencies in B12 are a result of intake (you have to eat animal foods, period), absorption, and how much gets secreted by the liver. With vegans relying on foods that inhibit B12 absorption (look at the quote above), they have double-trouble. Well, they would if they were getting any in their diet anyways.

    But, how do you aid absorption? Eat plenty of nutrients so you’re not malnourished (you mentioned alcoholics, which isn’t exactly true; it’s any resulting malnutrition caused by excess alcohol) and have plenty of “enablers” to utilize what nutrients (including B12) you intake. Those enablers are animal fats.

    Vegan diets can’t work long term without health consequences, at all. Unless you’re eating over 10 pounds of a variety of vegetables, each, it ain’t going to happen, much less all the things plants, nuts, seeds, grains, etc. do to make sure they are NOT eaten or to ensure their nutrients stay locked up and out of reach, both things that inhibit total absorption by humans. (Ever see a documentary where a bird or animal eats a plant and they say that its seed is spread through its droppings? Think similar nutrient protective measures like that don’t happen with us?) Plants don’t WANT to get eaten; they want to propagate, like animals do, and they have measures to protect against that.

    It all goes back to the purpose of the research presented on this site and lived out by many traditional peoples: proper food preparation is key to make sure that you get all the nutrients you can out of any given food.

  9. Alexandra says:

    To tommy’s comment:
    “I’d suggest trying it again but add in plenty of nuts, seeds, legumes, fruits and veggies” — Tommy

    Hi Tommy. Have you lived in a place with nut and fruit trees (not commercial operations, but natural environments). I did. You barely get any nuts and fruits at all. My friends and I always did a mad rush to the fruit/nut trees as soon as they produced, and it was gone, gone, gone! There is barely more than a few pieces per person. Doesn’t even last a day or two. I was always very excited when the blackberries, chestnuts, plums, tangerines, walnut and apple trees started producing, my brothers and I ran there to make sure we would get some before the others ate them all. That’s because there are barely any. So I very much doubt that this is the foods we are supposed to be eating, it’s not enough to feed a person. Now you can buy huge cans of mixed nuts and there is lots of fruit available at the grocery store, but that’s not the case in nature, even if you do it on purpose it’s just doesn’t grow that much. So there is no way that it’s the intended diet for humans because there wouldn’t be enough to feed one person, let alone many people.

    And if you think legumes and seeds can provide everything you need, then you clearly have not read this article. Read it again and you’ll see there are things animal products give that legumes and seeds do not.

    You can see that the author included comparison between animal products and all those things you mentioned, that is, “nuts, seeds, legumes, fruits and veggies”. Read again, more carefully, and you’ll see 🙂


  10. Jess says:

    So, what you’re saying is that EVEN THOUGH all of these nutrients are readily available in plant foods, it’s way better to kill and consume another living, sentient being to get them, just because it takes less effort? What about all of the risks that go along with eating animal products (which I am aware that the WAPF mistakenly denies)? The liver of an animal is where all of the environmental toxins are stored~ it DOESN’T MATTER if they are “grown” organically! There are STILL toxins in the air they breathe and the water they drink! As far as your B12 section, I just LOVE that all of the focus is on veg’s yet no mention at all is made of B12 studies in “omnivores”, so how is this proof that meat-eaters are not deficient? Everyone has the potential to be deficient in B12, due to degraded soil. What is the WAPF’s excuse for our long digestive tract, which takes meat 3 days to pass through, rotting and putrifying the entire time? I have yet to hear an explanation on that one. Look, bottom line is that these days, we have access to ALL of the plant foods we need in order to thrive. Back in the day, people had to do what they did for survival. That doesn’t mean that it was the healthiest diet! Look at our modern inventions, like juicers~ with which we can easily obtain ALL of the nutrients we need from plant foods~ and grocery stores and the internet, where we can easily obtain a wide variety of foods that weren’t readily available in our ancestors’ days! We no longer NEED to slaughter other creatures to be healthy! Let’s EVOLVE NOT DEVOLVE!! Why are we looking backwards when we should be looking forward? We live in a completely different day and age! Has anyone ever heard of the Rastafarians? They are completely vegan, and THRIVING. As am I. On a proper, well thought out and planned raw vegan diet. Life, IMHO, is much more important than CONVENIENCE.

    • KaD says:

      Some of us have mentally evolved beyond vegan. We realize that plants are conscious too, consciousness is inherent in creation; even in the things we don’t think of as ‘alive’. We realize you cannot live in this world without taking life; that is not a sin it is simply the way it is and the cycle of life that has existed since the earth had life on it.

    • Diane says:

      If I can survive and be healthy, thriving even, on a plant based diet with supplements to enhance the things that are harder to obtain from these sources, why would I ever choose to kill and eat another creature to sustain myself? These animals don’t want to die any more than you or I do.

  11. Pat C. says:

    Thanks for presenting many valuable points and have packed your article with helpful information and statistics. I agree that animal foods are essential for health.

    The zinc area of the article overlooks seeds and nuts. Pumpkin and sunflower seeds (among others) are higher in zinc per 100g than all of the animal sources you have listed except oysters. Seeds and nuts are also packed with other important minerals like selenium, magnesium, copper, manganese, and phosphorus, often in levels quite a bit higher than animal sources, and seeds and nuts are something that would have been easier for someone in a large group of hunter/gatherers to come across at a high frequency (daily) compared to organ meats of specific animals. Seeds and nuts are also by far the best source of vitamin E, and high in some B vitamins, such as B6, Thiamin, and Riboflavin. Hopefully the author will make a correction and include nuts and seeds as plant foods across all nutrient sections in order to present a more accurate picture.

  12. Nicola says:

    The above article advised vegans/vegetarians to consume red palm oil. It is now known that red palm oil harvesting is involved with major deforestation and destroying the natural habitat of many animals. There are better choices here is a app which can advise you which foods contain red palm oil

  13. KaD says:

    Anyone can feel great on a vegan diet-for a while. Sometimes years. But the FACT remains that humans evolved by and for eating meat. No one can buck millions of years of evolution indefinitely.

  14. Diane says:

    No mention of the fact that we are descendants of Gorillas. Gorillas are vegetarians. Those canine teeth we all have that people swear mean we are meant to tear apart animal flesh…..have you noticed the ones a GORILLA possesses? Our bodies reject animal flesh much more than they utilize it. And cows milk? You are not a calf. Therefore you have no need to ingest a cows breast milk. Do you really believe your human body was designed for this? We eat parts of animals that are not in any way fit for consumption. Liver? The organ that pulls toxins from the animals system and yet we are cooking and EATING it. Ingesting the very toxins that were rejected by that animals body. And the soy you stated you consumed may be the very thing that caused your health to deteriorate. There are much better options as outlined by another reader, seeds, nuts, coconut and olive oils…legumes….fruits and veggies…etc… If your argument is that eating a diet including animal products is easier, perhaps it is, but I would much rather eat ethically than easily.

  15. Susan says:

    Pat C., It’s not the nutrients IN nuts, seeds or any other food that counts, it’s what you absorb. Nuts and seeds contain phytic acid which blocks absorption of the *minerals* they contain. *Proper* soaking removes the phytic acid. You can read about both phytic acid and oxalic acid (both of which are in common foods, interfering mineral absorption) here in WAPF and numerous other sites online. Also, I do not take my mineral supplements with phytic or oxalic acid containing foods.

    Of course, there are some common, and often *hidden* problems within the body that interfere with absorption of nutrients, such as leaky gut, imbalanced gut microbiome and more. These can be corrected when properly addressed.

  16. Susan says:

    VITAMIN B12 in meat is POORLY absorbed according to research. B12 from dairy and B12 supplements are well absorbed (for people who do not have nutrient absorption problems, and are not dairy intolerant). For people (like me) who cannot have dairy, supplemental B12 is necessary. I eat meat (mostly chicken) and I tested deficient in B12 even by conventional standards. Even sublingual B12 does not raise levels enough for some people who end up doing well with B12 injections.

    • Mal says:

      Chicken is one of the single worst sources of animal B12 unless you’re eating raw livers. B12 is NOT poorly absorbed from meat, it’s destroyed by cooking. Beef liver is the purest, most bioavailable form and can be eaten as things like lightly-cooked livercheese and other such foods. When you say “according to research”, you are dismissing the fact that the one who posted this based it on scientific data obtained from clinical trials.

      If you want better B12 without supplements, stop eating grains and legumes, as they interfere; avoid plant-based because those are just components which the human body does not utilize at all; eat rich, dark, red meats from organ sources rather than muscle, because muscle tissue is nutritionally poor and you need the fat from it to digest it, too; eat copious amounts of fat and moderate protein while keeping carbohydrates extremely low and limited to lots of vegetables and moderate amounts of fruit; the B12 from dairy has to be raw, otherwise it’s denatured and difficult to absorb; you also should reduce intake of leafy green vegetables if you eat a lot, because they interfere with B12 digestibility and mask deficiency.

      You are not a model for all people, you have a serious physiological problem that is not shared with 99% of people. You should be tested for diseases which cause B12 complications, as well as take a look at your diet. I don’t know your diet, but as a nutritionist, that’s the first thing I would fix in a patient such as yourself, starting with laying off the chicken and switching to healthy red meats, instead.

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