The health implications of a vegan diet

Vegans, excluding dairy products, eggs and any other animal products from their diets, tend to eat significantly higher levels of particular vitamins and minerals than individuals with standard diets. A typically vegan diet will have much higher levels of Vitamin C, Vitamin E, folic acid, magnesium and dietary fibres. Conversely, they also tend to have a lower calorie count, cholesterol, omega-3 fatty acids, Vitamin D, Vitamin B12, iron, calcium and zinc than diets which contain animal products (1).

Health benefits associated with veganism

The question of the distinct health advantages of being a vegan is a complex one. The question is often framed as being beneficial in comparison to diets that include animal products, yet this is a difficult comparison to evaluate and study due to the wide range of confounding variables that contribute to good health and longer life. It is difficult to separate the health benefits of veganism from other practices such as not smoking, levels of exercise, and not drinking excessively. 

Heart Health

There is some clinical evidence that vegans have a lower risk of heart attack and death from cardiac causes compared to those who have diets including meat. 

A famous large prospective epidemiological study, comparing vegan and non-vegan Seventh Day Adventists (a religious group that avoid caffeine and don’t drink or smoke), found vegans to have significantly less incidence of cardiovascular disease (3,4). The sample also acknowledged and controlled for additional variables that are protective factors in longer life expectancy such as exercise and tobacco avoidance, as have a wide range of other large cohort studies with similar findings (5).

Longer life and reduced risk of chronic disease

In comparison to individuals who consume meat, vegans tend to consume much less saturated fat and cholesterol, and eat many more phytochemicals (chemical compounds that occur naturally in plants). As such, vegans tend to have:

• lower levels of low-density lipoprotein (LPL) cholesterol
• lower body mass index (BMI)
• lower blood pressure

All of which have an evidenced association with longer life and a reduced risk of a wide range of chronic diseases (2).

Health risk factors associated with veganism

Although veganism carries significant health benefits, the strict requirements of the diet also place vegans at a higher risk of particular diseases. 

• Deficiency of calcium. The EPIC-Oxford study, involving 65,000 research participants, evidenced a reduced risk of cardiovascular disease in vegans but a significantly higher risk of bone fractures and osteoporosis, with less than 75% of vegan participants receiving their recommended daily allowance of calcium (6). This appears to be as a result of a lower mean calcium uptake than both vegetarians and meat and fish eaters. Similarly, a lack of calcium (hypocalcemia), as well as contributing to low bone density, can manifest as muscle cramps, abdominal cramps and a highly irritable nervous system.
   
• Deficiency in iron can also cause anaemia, and iron deficiency can also manifest itself as an enlarged spleen, frequent infections, brittle nails, and swelling and/or soreness of the tongue.
   
• A lack of Vitamin B12 can also result in folate deficiency anaemia, and is most common in older people.
   
• Vitamin D is essential for regulating the amount of calcium and phosphate in our bodies, and ensuring bones and teeth remain healthy. Vegan diets are often low in Vitamin D, and require additional supplementation. This is especially true for vegans living in countries with relatively low levels of sunlight, as the body generates Vitamin D under the skin in response to the sun.

Good dietary planning is essential

Good planning is essential when following a vegan diet to ensure that it meets all the nutritional and mineral requirements of each individual.

The lack of iron, calcium, Vitamin B12 and Vitamin D that is common with many vegan diets may be addressed through a number of non-pharmaceutical methods such as eating plenty of fruit and vegetables, starchy foods, beans, pulses and dairy alternatives such as fortified soya drinks. Allthough supplementing may be necessary. 

The lack of certain minerals and vitamins in a vegan diet can have a particularly negative effect on developing children, and many organisations recommend supplementary Vitamin A, C, D and iron for many children.

Babies who are solely breastfed are recommended to receive all the vitamin supplements, as vegan parents are also less likely to transmit adequate levels of the requisite minerals and vitamins naturally that a young child requires to develop appropriately (7,8).

Fortified soy milk is a popular dietary choice among many vegans as a reliable source of calcium, and is reinforced by a strong body of evidence (9).

A lack of Vitamin B12 often results in iron deficiency anaemia. It is important that B12 as a dietary component is addressed at the outset of commencing a vegan diet, as prolonged periods of deficiency can result in a number of health problems such as temporary infertility, heart conditions and pregnancy complications (13).

This extends to a need for detailed planning and knowledge of plant-based nutrition, and being aware of the consequences of not incorporating all the vitamins and minerals that are required for a healthy, balanced diet.

References

1. Craig WJ. (2009). Health effects of vegan diets. Amer Jour Clin Nutr 89(5) pp.1627S-1633S
2. Nestle M. (1999). Animal vs. Plant foods in human diets and health: is this historical record unequivocal? Proceedings of the Nutrition Society, 58(2), May 1999, pp. 211–218 (review).
3. Fraser GE. (1999). Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. Am J Clin Nutr. 70(3 Suppl):532S-538S.
4. Beezhold B, Johnston C, Daigle D. (2010). Vegetarian diets are associated with healthy mood states: a cross-sectional study in Seventh Day Adventist adults. Nutrition Journal 9:26.
5. Smit E, Nieto FJ, Crespo CJ. (1999). Blood cholesterol and apolipoprotein B levels in relation to intakes of animal and plant proteins in US adults. Br J Nutr. 82(3):193-201
6. Appleby P. et al. (2007). Comparative fracture risk in vegetarians and non-vegetarians in EPIC-Oxford. Eur Jour Clin Nutr 61(12) pp.1400-1406
7. American Academy of Paediatrics Community on Nutrition. (2010). Soy protein-based formulas: recommendations for use in infant feeding. Pediatrics 126:1040-50
8. Shinwell ED, Gorodischer R. (1982). Totally vegetarian diets and infant nutrition. Pediatrics 70:582-586
9. Smith JD, Clinard V, Barnes CL. (2003). Pharmacist guide to infant formulas for term infants. J Am Pharm Assoc 51(3):e28-35; quiz e36-7.
10. Milman N. (2008). Prepartum anaemia: prevention and treatment. Ann Hematol. 87(12):949-59
11. Polkinghorne KR, Zoungas S, Branley P, Villaneuva E, McNeill JJ, Atkins RC, McGrath BP, Kerr PG. (2003). Randomized, placebo-controlled trial of intramuscular vitamin B12 for the treatment of hyperhomocysteinaemia in dialysis patients. Intern Med J 33(11):489-94
12. Gonzalez-Gonzalez C, Figueiras A. (2014). Gastric acid-inhibiting medications and vitamin B12 deficiency. JAMA 9;311(14)1445
13. Jacquemyn Y, Ajaji M, Karepouan N, Jacquemyn N, Van Sande H. (2014). Vitamin B12 and folic acid status of pregnant women and newborns in the Antwerp region, Belgium. Clin Exp Obstet Gynecol. 41(2):141-3.