Vegan nutrition refers to the unique set of advantages and challenges that are part of vegan diets. The American Dietetic Association and Dietitians of Canada regard the vegan diet as appropriate for all stages of the life-cycle and as offering protection against cardiovascular disease, cancer, and other diseases. They caution that poorly planned vegan diets can be deficient in vitamin B12, vitamin D, calcium, iodine, iron, zinc, riboflavin (vitamin B2) and omega-3 fatty acids. Just as with omnivorous and vegetarian diets, ensuring a balanced diet is key.
Doctors Dean Ornish, T. Colin Campbell, John A. McDougall, Michael Klaper, Caldwell Esselstyn, Michael Greger, Joel Fuhrman, and Neal D. Barnard claim that high animal fat and protein diets, such as the standard American diet, are detrimental to health. They also state that a lifestyle change incorporating a vegan whole foods diet could not only prevent various degenerative diseases, such as coronary artery disease, but reverse them. A number of documentary films, such as Fat, Sick and Nearly Dead, Planeat and Forks over Knives, focus on the purported health benefits of plant-based diets. Although there is general consensus amongst doctors advocating plant-based diets, Joel Fuhrman and Michael Greger have disagreed with Campbell and Esselstyn on the use of nuts and seeds.
Some top athletes, such as Brendan Brazier, follow a vegan diet, including raw veganism. Vegan diets tend to be higher in dietary fibre, magnesium, folic acid, vitamin C, vitamin E, iron, and phytochemicals, and lower in calories, saturated fat, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc, and vitamin B12. Because uncontaminated plant foods do not provide vitamin B12 (which is produced by microorganisms such as bacteria), researchers agree that vegans should eat foods fortified with B12 or take a daily supplement.
Poorly planned vegan diets may be low in vitamin B12, omega-3 fatty acids, vitamin D, calcium, iron, zinc, riboflavin (vitamin B2), and iodine. Nonetheless, well-balanced vegan diets can meet all these nutrient requirements and are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence.
Evidence suggests that vegans who are not taking vitamin B12 supplements do not consume sufficient servings of B12 and often have abnormally low blood concentrations of vitamin B12. This is because, unless fortified, plant foods do not contain reliable amounts of active vitamin B12.
The Vegan Society and Vegan Outreach recommend that vegans eat foods fortified with B12 or take a supplement.
Proteins are composed of amino acids, and a common though unfounded concern with protein acquired from vegetable sources is an adequate intake of the essential amino acids, which cannot be synthesised by the human body. Dairy and egg products provide complete protein sources for ovo-lacto vegetarians, and some vegetable sources of complete proteins include broccoli, cauliflower, potato, spinach, kiwi, chestnuts, cashews, pumpkin seeds, chickpeas, kidney beans, black beans, avocados, soy, hempseed, chia seed, amaranth, buckwheat, and quinoa although amounts of protein per food varies considerably. However, the essential amino acids can also easily be obtained by eating a variety of complementary plant sources that, in combination, provide all eight essential amino acids (e.g. brown rice and beans, or hummus and whole wheat pita, though protein combining in the same meal is not necessary). A 1994 study found a varied intake of such sources can be adequate. The source and composition of vegan proteins have been associated with a reduced risk in cancer and other comorbidities including cardiovascular disease.
Omega-3 fatty acids
Vegan diets can be low in omega-3 fatty acids (O3FA). Major vegan sources of O3FA include algae, hempseeds and hempseed oil, walnuts, flaxseeds and flaxseed oil, olive oil, canola (rapeseed) oil, avocado and chia seeds. However, diets lacking generous amounts of sea vegetables (seaweed) generally lack a direct source of long-chain O3FA such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Vegan diets, like the standard American diet, may also have a high ratio of O6FA to O3FA, which inhibits the conversion of short-chain fatty acids such as alpha-Linolenic acid (ALA), found in most vegan O3FA sources, to EPA and DHA. Short-term supplemental ALA has been shown to increase EPA levels but not DHA levels, suggesting poor conversion of the intermediary EPA to DHA. DHA supplements derived from DHA-rich microalgae are available, and the human body can also convert DHA to EPA.
While there is no scientific consensus on the role of omega-3 fatty acids, they may reduce the risk of coronary heart disease, lower triglycerides, stabilize mood and help prevent depression, help reduce symptoms of ADD, reduce joint pain and other rheumatoid problems, and reduce the risk of dementia in older age. While there is little evidence of adverse health or cognitive effects due to DHA deficiency in adult vegetarians or vegans, fetal and breast milk levels remain a concern. EPA and DHA supplementation has been shown to reduce platelet aggregation in vegetarians, but a direct link to cardiovascular morbidity and mortality, which is already lower for vegetarians, has yet to be determined.
The human body can synthesize vitamin D when skin is exposed to ultraviolet radiation from the sun. If vegans cannot obtain enough vitamin D from exposure to sunlight, it is recommended that they eat foods or pills fortified with synthetic vitamin D2 (vitamin D3 supplements are animal-derived, mainly from lanolin). Those 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.
It is recommended that vegans eat three servings per day of a high-calcium food, such as fortified soy milk, almonds, hazelnuts, kale, collard greens, Chinese greens, and take a calcium supplement or other calcium-fortified foods as necessary.
Many studies have examined possible correlation between veganism, calcium intake and bone health. The EPIC-Oxford study suggested that vegans who consumed 525 mg or less of calcium per day have an increased risk of bone fractures over meat eaters and vegetarians, but that vegans consuming more than 525 mg/day had a risk of fractures similar to other groups. Overall, the entire group of vegans had a higher risk of fractures. A 2009 study of bone density found the bone density of vegans was 94 percent that of omnivores, but deemed the difference clinically insignificant. Another study in 2009 by the same researchers examined over 100 vegan post-menopausal women, and found that their diet had no adverse effect on bone mineral density (BMD) and no alteration in body composition. Biochemist T. Colin Campbell suggested in The China Study (2005) that osteoporosis is linked to the consumption of animal protein because, unlike plant protein, animal protein increases the acidity of blood and tissues, which is then neutralized by calcium pulled from the bones resulting in hypercalciuria. Campbell wrote that his China-Oxford-Cornell study of nutrition in the 1970s and 1980s found that, in rural China, "where the animal to plant ratio [for protein] was about 10 percent, the fracture rate is only one-fifth that of the U.S."
Calcium is one component of the most common type of human kidney stones, calcium oxalate. Some studies suggest that people who take supplemental calcium have a higher risk of developing kidney stones, and these findings have been used as the basis for setting the recommended daily intake (RDI) for calcium in adults.
One study reported a "potential danger of iodine deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low [iodine] levels are ingested."
It is recommended for vegans to eat food rich in choline, as plant based sources of choline are limited. Soy lecithin, cauliflower, spinach, wheat germ, firm tofu, kidney beans, quinoa and amaranth are vegan sources of choline. The Adequate Intake (AI) of choline is 425 mg (milligrams) per day for adult women; higher for pregnant and breastfeeding women. The AI for adult men is 550 mg/day. Choline deficiency can lead to health problems such as liver damage, a result of liver cells initiating programmed cell death (apoptosis), as well as an increase in neural tube defects in pregnant women. In a study, 77% of men, 44% of premenopausal women, and 80% of postmenopausal women developed fatty liver or muscle damage due to choline deficiency, showing that subject characteristics regulate the dietary requirement. Choline deficiency has also been associated with hypertension in rats. There is also some evidence that choline is an anti-inflammatory as well, but further studies are needed to confirm/refute findings. In order to avoid these problems, it's important to meet the adequate intake, especially since many multivitamins do not contain enough choline. Although many animal products, like liver and egg, contain high amounts of choline (355 mg/3 oz and 126 mg/large egg, respectively), wheat germ (172 mg/cup), brussel sprouts (63 mg/cup), and broccoli (62 mg/cup) are good sources of choline as well.
- Diet for a New America (1991) by John Robbins; featuring Michael Klaper, T. Colin Campbell and John A. McDougall
- A Diet for All Reasons (1993) by Michael Klaper
- Eating (2002) by Mike Anderson; featuring Caldwell Esselstyn and John A. McDougall
- Total Health Solution (2003) by John A. McDougall
- Simply Raw: Reversing Diabetes in 30 Days (2009) by Gabriel Cousens; featuring Joel Fuhrman
- Latest in Clinical Nutrition (2010) by Michael Greger
- Fat, Sick and Nearly Dead (2010) by Joe Cross; featuring Joel Fuhrman
- Planeat (2010) by Shelley Lee Davies and Or Shlomi; featuring T. Colin Campbell and Caldwell Esselstyn
- Forks over Knives (2011) by Lee Fulkerson; featuring T. Colin Campbell, Caldwell Esselstyn and Neal D. Barnard
- Vegucated (2011) by Marisa Miller Wolfson; featuring T. Colin Campbell and Joel Fuhrman
|This article lacks ISBNs for the books listed in it. (June 2012)|
- Dean Ornish (1996) Dr. Dean Ornish's Programme for Reversing Heart Disease
- John A. McDougall (1996) The McDougall Program for a Healthy Heart
- Physicians Committee for Responsible Medicine (2002) Healthy Eating for Life to Prevent and Treat Cancer
- Joel Fuhrman (2003) Eat to Live
- T. Colin Campbell (2005) The China Study
- Michael Greger (2005) Carbophobia!
- Will Tuttle (2005) World Peace Diet
- Neal D. Barnard (2007) Dr. Neal Barnard's Program for Reversing Diabetes
- Caldwell Esselstyn (2008) Prevent and Reverse Heart Disease
- Barnard, Neal D; Cohen, Joshua; Jenkins, David JA; Turner-Mcgrievy, Gabrielle; Gloede, Lise; Green, Amber; Ferdowsian, Hope (2009). "A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: A randomized, controlled, 74-wk clinical trial". American Journal of Clinical Nutrition 89 (5): 1588S–1596S. doi:10.3945/ajcn.2009.26736H. PMC 2677007. PMID 19339401.
- Jacobs, David R; Gross, Myron D; Tapsell, Linda C (2009). "Food synergy: An operational concept for understanding nutrition". American Journal of Clinical Nutrition 89 (5): 1543S–1548S. doi:10.3945/ajcn.2009.26736B. PMC 2731586. PMID 19279083.
- Fraser, Gary E (2009). "Vegetarian diets: What do we know of their effects on common chronic diseases?". American Journal of Clinical Nutrition 89 (5): 1607S–1612S. doi:10.3945/ajcn.2009.26736K. PMC 2677008. PMID 19321569.
- For an overview, see:
- American Dietetic, Association; Dietitians Of, Canada (2003). "Position of the American Dietetic Association and Dietitians of Canada : Vegetarian Diets". Canadian Journal of Dietetic Practice and Research 64 (2): 62–81. doi:10.3148/64.2.2003.62. PMID 12826028.
- Key, Timothy J.; Appleby, Paul N.; Rosell, Magdalena S. (2007). "Health effects of vegetarian and vegan diets". Proceedings of the Nutrition Society 65 (1): 35–41. doi:10.1079/PNS2005481. PMID 16441942.
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- For vitamin B12: Norris, Jack (July 26, 2006). "Vitamin B12: Are you getting it?". Vegan Outreach. Retrieved February 4, 2011. "B12 is generally found in all animal foods (except honey). Contrary to rumors, there are no reliable, unfortified plant sources of vitamin B12, including tempeh, seaweeds, and organic produce. The overwhelming consensus in the mainstream nutrition community, as well as among vegan health professionals, is that plant foods do not provide vitamin B12, and fortified foods or supplements are necessary for the optimal health of vegans, and even vegetarians in many cases. Luckily, vitamin B12 is made by bacterial fermentation such that it does not need to be obtained from animal products."[unreliable medical source?]
- For vitamin D: "Bones, Vitamin D, and Calcium". Vegan Outreach. January 9, 2007. Retrieved February 4, 2011. "If you get exposed to the following amounts of midday sun (10 am to 2 pm), without sunscreen, on a day when sunburn is possible (i.e., not winter or cloudy), then you do not need any dietary vitamin D that day."[unreliable medical source?]
- For calcium: "Bones, Vitamin D, and Calcium". Vegan Outreach. January 9, 2007. Retrieved February 4, 2011. "Based on research showing that vegans who consumed less than 525 mg per day of calcium had higher bone fracture rates than people who consumed more than 525 mg per day (14), vegans should make sure they get a minimum of 525 mg of calcium per day. It would be best to get 700 mg per day for adults, and at least 1,000 mg for people age 13 to 18 when bones are developing. This can most easily be satisfied for most vegans by eating high-calcium greens on a daily basis and drinking a nondairy milk that is fortified with calcium."[unreliable medical source?]
- For vitamin D and calcium: Appleby, P; Roddam, A; Allen, N; Key, T (2007). "Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford". European Journal of Clinical Nutrition 61 (12): 1400–6. doi:10.1038/sj.ejcn.1602659. PMID 17299475.
- For iodine: "Iodine". Vegan Outreach. December 26, 2006. Retrieved February 4, 2011. "Iodine is needed for healthy thyroid function which regulates metabolism. Both too much, and too little iodine can result in abnormal thyroid metabolism. ... Studies have shown that vegans in Europe (where salt is either not iodized or not iodized at high enough levels) who do not supplement (as well as those who oversupplement) have indications of abnormal thyroid function"[unreliable medical source?]
- For iron: "Iron deficiency—adults". Better Health Channel. Government of Victoria, Australia. Retrieved February 4, 2011. "High-risk groups such as vegetarians, adolescent girls and women athletes need to eat iron-rich foods each day (combined with foods that are high in vitamin C). …Vegetarians who exclude all animal products from their diet may need almost twice as much dietary iron each day as non-vegetarians. Sources include dark green leafy vegetables—such as spinach—and raisins, nuts, seeds, beans, peas, and iron-fortified cereals, breads and pastas."[unreliable medical source?]
- For omega-3 fatty acids: "Omega-3 Fatty Acid Recommendations for Vegetarians". Vegan Outreach. Retrieved February 4, 2011. "Without diet planning, vegans and vegetarians have low omega-3 intakes and blood levels; and in some cases, elderly vegans have close to none"[unreliable medical source?]
- Segelken, Roger (2001-06-28). "China Study II: Switch to Western diet may bring Western-type diseases". Cornell Chronicle. Retrieved 2006-09-15.
- "China-Cornell-Oxford Project On Nutrition, Environment and Health at Cornell University". Division of Nutritional Sciences. Cornell University. Retrieved 2006-09-15.
- Barnard, Neal D. (2007). Dr. Neal Barnard's Program for Reversing Diabetes. New York: Rodale. pp. 40–50. "Set aside animal products"
- Ornish, D.; Brown, S.E.; Billings, J.H.; Scherwitz, L.W.; Armstrong, W.T.; Ports, T.A.; McLanahan, S.M.; Kirkeeide, R.L.; Gould, K.L. et al. (1990). "Can lifestyle changes reverse coronary heart disease?". The Lancet 336 (8708): 129–33. doi:10.1016/0140-6736(90)91656-U. PMID 1973470.
- Goldhamer, Alan C.; Lisle, Douglas J.; Sultana, Peter; Anderson, Scott V.; Parpia, Banoo; Hughes, Barry; Campbell, T. Colin (2002). "Medically Supervised Water-Only Fasting in the Treatment of Borderline Hypertension". The Journal of Alternative and Complementary Medicine 8 (5): 643–50. doi:10.1089/107555302320825165. PMID 12470446.
- McDougall, John; Bruce, Bonnie; Spiller, Gene; Westerdahl, John; McDougall, Mary (2002). "Effects of a Very Low-Fat, Vegan Diet in Subjects with Rheumatoid Arthritis". The Journal of Alternative and Complementary Medicine 8 (1): 71–5. doi:10.1089/107555302753507195. PMID 11890437.
- Esselstyn, Caldwell B (1999). "Updating a 12-year experience with arrest and reversal therapy for coronary heart disease (an overdue requiem for palliative cardiology)". The American Journal of Cardiology 84 (3): 339–41, A8. doi:10.1016/S0002-9149(99)00290-8. PMID 10496449.
- Barnard, N. D.; Cohen, J; Jenkins, DJ; Turner-Mcgrievy, G; Gloede, L; Jaster, B; Seidl, K; Green, AA; Talpers, S (2006). "A Low-Fat Vegan Diet Improves Glycemic Control and Cardiovascular Risk Factors in a Randomized Clinical Trial in Individuals with Type 2 Diabetes". Diabetes Care 29 (8): 1777–83. doi:10.2337/dc06-0606. PMID 16873779.
- "The Diet Wars: The Time for Unification Is Now". The McDougall Newsletter (Volume 11, Issue 8). August 2012.
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- "Despite the seeming hardships a vegan diet imposes on its practitioners, veganism is a burgeoning movement, especially among younger Americans. In the endurance sports, such as the Ironman triathlon and the Utramarathon, the top competitors are vegans who consume much of their vegan food in its uncooked state. Even young weight lifters and body builders are gravitating to a vegan diet, giving the lie to the notion that eating animal flesh is essential for strength and stamina. Brendan Brazier, a young athlete who regularly places in the top three in international triathlon events and who formulated Vega, a line of plant-based performance products, said of his fellow vegan athletes: 'We're beginning to build a strong presence in every sport.'"
- Also see Nijjar, Raman. "From pro athletes to CEOs and doughnut cravers, the rise of the vegan diet", CBC News, June 4, 2011.
- For other examples of Ironman triathlon athletes who are vegan, see Scott, David and Heidrich, Ruth. "Vegetarian/Vegan Ironman and Ironlady", European Vegetarian Union News, issue 4, 1997.
- Craig, Winston J. "Health effects of vegan diets", The American Journal of Clinical Nutrition, 89(5), May 2009, pp. 1627S–1633S (review article).
- Mangels, Reed; Messina, Virginia; and Messina, Mark. "Vitamin B12 (Cobalamin)," The Dietitian's Guide to Vegetarian Diets. Jones & Bartlett Learning, 2011, pp. 181–192.
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- "Vitamin B12", Office of Dietary Supplements, National Institutes of Health, accessed December 17, 2012.
- Norris, Jack. "Vitamin B12: Are you getting it?", Vegan Outreach, July 26, 2006: "Contrary to the many rumors, there are no reliable, unfortified plant sources of vitamin B12 ... [There is an] overwhelming consensus in the mainstream nutrition community, as well as among vegan health professionals, that vitamin B12 fortified foods or supplements are necessary for the optimal health of vegans, and even vegetarians in many cases. Luckily, vitamin B12 is made by bacteria such that it does not need to be obtained from animal products."
- "Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets", Canadian Journal of Dietetic Practice and Research, Summer 2003, 64(2), pp. 62–81 (also available here).
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