Vegan Diets Come With Many Benefits, Some Risks

by | May 2, 2016 | 2009, Cardiovascular Health, Vegetarianism

Written by Greg Arnold, DC, CSCS. Vegan diet is rich in antioxidants but significantly low in calcium and vitamin D.

In 2006 an estimated 1.4% of Americans followed a vegan diet by avoiding meat, fish, dairy, or eggs (1). While the goals of those who follow vegan diets are for the health benefits of a plant-based diet, they also stem from a concern for taking better care of the earth’s resources and the environment, ethical issues about animal care, and the use of antibiotics and growth stimulants (2).

The health benefits of a vegan diet center on research showing significant reductions in the risks of heart disease (3) due to 32% lower total cholesterol levels and 44% lower  LDL cholesterol levels observed in vegans (4). Vegan diets may also reduce the risk of colorectal (5), liver and lung (6), and prostate (7) cancer because of the avoidance of processed meats as well as the increased intakes of legumes (8) and antioxidants called phytochemicals (9).

But there are concerns with a vegan diet, the first of which may be bone health as vegans can have low calcium intake due to their avoidance of dairy. A threshold of 525 milligrams of calcium per day seems adequate to help minimize fracture risk (10).

Other nutritional concerns include vitamin D intake as vegans consume 75% lower levels than meat eaters (4).  Vitamin B12 levels are also low among vegans which can elevate homocysteine levels (11), a known risk factor for cardiovascular disease (13) and osteoporotic bone fractures (12). Finally, the high levels of grain intake may cause a zinc deficiency in vegans as grains contain high levels of phytates which bind zinc and prevent absorption (14).

A 2009 review study (15) came up with 5 dietary recommendations for vegans:

  1. Consume vitamin B-12–fortified foods, such as fortified soy and rice beverages, certain breakfast cereals and meat analogs, B-12–fortified nutritional yeast, or take a daily vitamin B-12 supplement.
  2. In addition to green leafy vegetables, consume calcium-fortified foods such as ready-to-eat cereals, calcium-fortified soy and rice beverages, calcium-fortified orange and apple juices, and other beverages.
  3. Consume vitamin D–fortified foods such as soy milk, rice milk, orange juice, breakfast cereals, or a daily supplement providing 5–10 micrograms/day vitamin D.
  4. Consume plant foods naturally rich in the omega 3 fatty acids such as ground flaxseed, walnuts, canola oil, soy products, and hemp seed–based beverages.
  5. Consume foods rich in zinc such as whole grains, legumes, and soy products, to provide a sufficient zinc intake.

Source:  Craig, Winston J. “Health effects of vegan diets.” The American journal of clinical nutrition 89.5 (2009): 1627S-1633S.

© 2009 American Society for Nutrition

Posted July 15, 2014.

References:

  1. Stahler C. How many adults are vegetarian? Veg J 2006;25:14–5
  2. Jacobsen MF. Six arguments for a greener diet: how a more plant-based diet could save your health and the environment. Washington, DC: Center for Science in the Public Interest, 2006.
  3. De Biase SG, Fernandes SF, Gianini RJ, Duarte JL. Vegetarian diet and cholesterol and triglyceride levels. Arq Bras Cardiol 2007;88:35–9
  4. Davey GK, Spencer EA, Appleby PN, Allen NE, Knox KH, Key TJ. EPIC-Oxford: lifestyle characteristics and nutrient intakes in a cohort of 33,883 meat-eaters and 31,546 non meat-eaters in the UK. Public Health Nutr 2003;6:259–69
  5. World Cancer Research Fund. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington, DC: American Institute for Cancer Research, 2007
  6. . Cross AJ, Leitzmann MF, Gail MH, Hollenbeck AR, Schatzkin A, Sinha R. A prospective study of red and processed meat intake in relation to cancer risk. PLoS Med 2007;4:e325.
  7. Park SY, Murphy SP, Wilkens LR, Henderson BE, Kolonel LN. Legume and isoflavone intake and prostate cancer risk: the Multiethnic Cohort Study. Int J Cancer 2008;123:927–32.
  8. Larsson CL, Johansson GK. Dietary intake and nutritional status of young vegans and omnivores in Sweden. Am J Clin Nutr 2002;76 100–6
  9. Liu RH. Potential synergy of phytochemicals in cancer prevention: mechanism of action. J Nutr 2004;134(suppl):3479S–85S.
  10. Appleby P, Roddam A, Allen N, Key T. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr 2007; 61:1400–6
  11. Majchrzak D, Singer I, Manner M, et al. B-vitamin status and concentrations of homocysteine in Austrian omnivores, vegetarians and vegans. Ann Nutr Metab 2006;50:485–91
  12. McNulty H, Pentieva K, Hoey L, Ward M. Homocysteine, B-vitamins and CVD. Proc Nutr Soc 2008;67:232–7.
  13. McLean RR, Jacques PF, Selhub J, et al. Plasma B vitamins, homocysteine and their relation with bone loss and hip fracture in elderly men and women. J Clin Endocrinol Metab 2008;93:2206–12.
  14. Hunt JR. Moving towards a plant-based diet: are iron and zinc at risk. Nutr Rev 2002;60:127–34
  15. Craig WJ. Health effects of vegan diets. Am J Clin Nutr 2009 May;89(5):1627S-1633S. doi: 10.3945/ajcn.2009.26736N. Epub 2009 Mar 11