Vegetarian nutrition is a subject of importance to both vegetarians and dietitians.

According to the American Dietetic Association (ADA), American Heart Association, National Institutes of Health, British Medical Association and the Mayo Clinic, vegetarian diets offer a number of health benefits compared to non-vegetarian diets.

As an example, vegetarians tend to have lower body mass indices, lower levels of cholesterol, lower blood pressure, and less incidence of heart disease, hypertension, some forms of cancer, type 2 diabetes, renal disease, osteoporosis, dementias such as Alzheimer’s Disease and other disorders that may be diet-related.

The Journal of the ADA also reports that children raised as vegans have approximately 20 more points of IQ than average. (source: JADA 1980; 76:142-7)

As with all diets, vegetarians should have a diverse and well-planned food intake for optimal health. Most western governments provide a recommended nutritional intake for their citizens. For vegetarians there are foods that a consensus of medical dietitians advise should be supplimented or concentrated upon. These foods are especially recommended for vegans, fruitarians, raw-foodists, macrobiotics and other "restrictive" forms of vegetarianism.

Protein

The typical vegetarian and vegan gets adequate protein if caloric intake is adequate and a variety of foods are eaten. However, a typical vegetarian gets less protein than the typical non-vegetarian. This is generally considered a benefit for two main reasons:

• Due to excess protein intake, people in affluent societies commonly lose about 30 percent of their kidney function by the time they reach their 80s (J Gerentol 31:155, 1976). The amount of protein typically consumed in the American diet, 12% to 15% protein, is probably a partial cause of this (New Eng Jrnl Med 307:652, 1982); by contrast, some high-protein diets, such as the Atkins diet recommend a 30% intake.
• Excessive protein intake — particularly sulfurous amino acids which predominate in animal proteins — causes systemic acidity. To counter this acidity the body then leaches calcium from bones, potentially causing osteoporosis.

Sources: Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Milk, Dietary calcium, and bone fractures in women: a 12-year prospective study. Amer Jrnl Public Health 1997;87:992-7. See also follow-up in February, 2003 issue of the American Journal of Clinical Nutrition (Vol. 77, No. 2, 504-511), which includes 72,000+ people and 18 years of data. Cumming RG, Klineberg RJ. Case-control study of risk factors for hip fractures in the elderly. Amer Jrnl Epidemiology 1994;139:493-503. Studies suggest that the Rural Chinese Diet - low-protein, no milk, and nearly vegan - results in less osteoporosis than the average Westerner's diet, as well as other health benefits similar to vegetarianism .

Protein is essential to both the structure and function of all living cells. Some soy-based meat analogues contain more protein per pound than beef (eg soy concentrate, which is similar to TVP). Sea vegetables also can provide even more protein per pound than beef. Wheat, rice, beans and nuts are also

Combining Proteins

A widely held myth in the United States about protein - and vegetarianism itself - is that vegetarians must carefully 'combine' various plant foods in their diets by consuming them within a few hours of each other in order to make a 'complete' protein which contains all 8 "essential amino acids". While this myth has been extensively published, it has never been substantiated by research, and cites research which refutes this myth. All plants contain varying levels of amino acids, and the modern PDCAAS rating attempts to evaluate proteins according to their digestibility by humans. A rating of "1" is the highest (including foods such as soybean plant and eggs). Sources suggest that even vegans who do not eat foods such as soy do not need to plan for 'complementary proteins' so long as their diet remains diverse . It is recommended that all diets, from veganism to meat-eating, should contain such diversity.

The protein combining myth was brought to popular attention in Frances Moore Lappe's 1971 besteller Diet for a Small Planet. In later editions of the book, as early as 1981, Lappe reversed her opinion that protein 'combining' is necessary. John McDougall MD, in The McDougall Plan, uses research to concur with Lappe's 1981 conclusion. McDougall says "many people believe that animal foods contain protein that is superior in quality to the protein found in plants. This is a misconception dating back to 1914, when Osborn and Mendel studied the protein requirements of laboratory rats. (11) .. It has since been shown that the initial premise that animal products supplied the most ideal protein pattern for humans, as it did for rats, was incorrect."

Even today, McDougall still aggressively challenges those who perpetuate the protein combining myth by demanding that they produce evidence to support their claims .

Iron

Surprisingly, even vegans seem not to suffer from iron deficiency any more than non-vegetarians do (source: Am J Clin Nutr. 1994;59 (suppl):1233S-1237S), but meat is the only source of heme iron; plants contain non-heme iron. The human body absorbs non-heme iron less efficiently.

However, heme iron has been shown to increase colon cancer risk due to cytotoxic factors (source: ). Non-heme iron is more sensitive to both inhibitors and enhancers of iron absorption; Vitamin C is an iron absorption enhancer, whilst inhibitors include tannins (tea, wine), phytates (legumes, grains), calcium and polyphenols.

Iron is an integral part of many proteins and enzymes which maintain good health. In humans, iron is an essential component of proteins involved in red blood cells' oxygen transportation. Iron also helps regulate cell growth and differentiation. Vegetarian sources of iron include tofu, potato skins, nuts and seeds, some beans and peas, green leafy vegetables, sea vegetables, whole-grain and enriched breads, miso, raisins, wheat germ and even foods cooked in cast-iron containers.

Excess amounts of iron can be toxic and even result in death.

Zinc

Vegetarians and vegans seem not to suffer from zinc deficiencies any more than meat-eaters (source: Freeland-Graves JH, Bodzy PW, Epright MA. Zinc status of vegetarians. J Am Diet Assoc. 1980;77:655-661). However, phylate in many whole-grains and fiber in many foods may interfere

Zinc is essential for building many enzymes, protein synthesis, reproductive health, immune system, speeds healing as a topical application, and may be an anti-oxidant. Plant sources of zinc include cooked dried beans, sea vegetables, fortified cereals, soyfoods, nuts, peas, and seeds.

High doses of zinc are thought to be a cause of cancer.

Vitamin B₁₂

Vitamin B-12 is produced only by bacteria, which are found in animals and plants alike (source: Mozafar, A. 1994. Enrichment of some B-vitamins in plants with application of organic fertilizers , Plant and Soil 167:305-311).

However, pesticides can kill these bacteria when applied to plants (ibid). If animals eat these B12-deficient plants, they may become B12-deficient themselves, and if humans eat these B12-deficient animals (or if humans eat only the deficient plants) humans may also become B12-deficient. Non-vegans have prevalent B12-deficiency (source: USDA-ARS Human Nutrition Research Center on Aging at Tufts University, and Framingham (Massachusetts) Offspring Study; as cited in: "Are You Vitamin B-12 Deficient?"; Aug. 2000 issue of Agricultural Research magazine). There is no reliable source of B-12 without dietary supplementation; B12-supplementation is recommended for people of any diet.

Although humans are able to absorb B12 from the beneficial bacteria within our intestines, and re-absorb nearly 100% of that which is digested, then excreted back into our intestines for re-usage (sources: Nature 1980 Feb 21;283(5749):781-2, Vitamin B12 synthesis by human small intestinal bacteria. Albert MJ, Mathan VI, Baker SJ. See also ), animals, including humans, must also ingest a minuscule amount of B-12 to maintain proper B-12 levels (source: Callender ST, Spray GH. Latent pernicious anemia. Br J Haematol 1962; 8: 230-240). However, someone of any diet, starting with a healthy level of B-12, typically lasts for decades without running critically deficient in this important nutrient. (source: Am J Clin Nutr 1988; 48: 852-858. Herbert V.; Vitamin B-12: Plant sources, requirements and assay).

Vitamin B-12 is necessary for DNA replication, so deficiencies can prevent rapid cell division, particularly of blood cells, which causes anemia. The human body also uses B-12 in the natural protein sheaths around nerves, so deficiencies can lead to potentially irreversible nerve degeneration. Vegetarian sources of Vitamin B-12 include eggs, dairy products, tempeh, some sea vegetables, Marmite and Vegemite, and pills fortified with synthetic supplements of Vitamin B-12.

Omega-3 fatty acids

Vegetarian sources of Omega-3 fatty acids include flaxseeds and flaxseed oil, walnuts, canola (rapeseed) oil and eggs. A well-known source for non-vegetarians is fish. Vegetarians recognise that humans need only consume one-third the weight of walnuts compared to salmon to get the same amount of Omega-3s; and flax seeds have even more highly-concentrated Omega-3s than walnuts (source: ).

However, vegetarian sources of Omega-3 fatty acids are primarily the short chain variety and likely to have lower concentrations of the particular essential fatty acids (EFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The body can synthesize small quantities of EPA and DHA from other Omega-3 fatty acids, such as alpha-linolenic acids, which are present in vegetarian sources of Omega-3 fatty acids.

The human body can also convert DHA into EPA. DHA supplements derived from DHA-rich microalgae are available. Whilst the human body can in theory do this conversion, in practice modern diets and lifestyles reduce the effectiveness of the conversion systems. Roughly ten times more of the short chain Omega-3s must be consumed to have the same effect as the long chain form from fish oil.

While there is no scientific consensus on the role of Omega-3 fatty acids, it is generally believed that they may reduce the risk of coronary heart disease, lower triglycerides, stabilize mood and help prevent depression, help prevent ADD, reduce joint pain and other rheumatoid problems and reduce the risk of dementia in older age.

Vitamin D

The human body can synthesize Vitamin D when skin is exposed to ultraviolet radiation from the sun. Vegans who do not eat foods or pills fortified with synthetic vitamin D and with little exposure to the sun's ultraviolet radiation, eg who don't expose their extremities for at least 15-30 minutes per day or those living at latitudes close to the poles, are vulnerable to Vitamin D deficiencies.

Vitamin D acts as a hormone, sending a message to the intestines to increase the absorption of calcium and phosphorus, which produces strong bones. Vitamin D also works in concert with a number of other vitamins, minerals, and hormones to promote bone mineralization. Research also suggests that vitamin D may help maintain a healthy immune system and help regulate cell growth and differentiation.

Iodine

Whilst very rare, some vegetarians (and some non-vegetarians), especially those who eschew iodized salt, do not get enough iodine (source: ). Two groups who often minimize salt intake are naturalists and those fearful of the fact that excessive salt contributes to hypertension. Both groups are commonly thought of as people who adopt a vegetarian diet. A good iodine source are sea vegetables, but many people, vegetarian and non-vegetarian alike, eat few or no sea vegetables. Some vegetarians and a few meat-eaters are further at risk due to eating too much soy or other foods containing goitrogens; goitrogens are thought to interfere with iodine uptake.

Lack of iodine in any diet may cause hypothyroidism, but excessive salt, iodized or not, may cause hypertension. Moderate amounts of iodized salt, an iodine supplement or other iodine intake usually avoids iodine deficiency. Until recent years, iodine used as a disinfectant on bread, meat and dairy processing equipment also provided iodine (ibid).

Diet and stamina

Dr Per-Olaf Astrand conducted an informal study of diet and endurance using nine highly-trained athletes, changing their diet every three days. At the end of every diet change, each athlete would pedal a bicycle until exhaustion.

Those with a high protein and high fat meat (carnivore) diet averaged 57 minutes. Those that consumed a mixed (omnivore) diet, lower in meat, fat and protein averaged 1 hour 54 minutes, twice the endurance of the meat and fat eaters.

The vegetarian, high carbohydrate diet athletes lasted 2 hours and 47 minutes, triple the endurance of the high-protein group (source: Astrand, Per-Olaf, Nutrition Today 3:no2, 9-11, 1968 )

See also

• Vegetarian cuisine
• Vegetarianism
• Veganism
• Vegan cuisine Dieta vegetariana