Pulls from Health effects of vegan diets by Winston J Craig
Micronutrients of special concern for the vegan include vitamins B-12 and D, calcium, and long-chain n–3 (omega-3) fatty acids. Unless vegans regularly consume foods that are fortified with these nutrients, appropriate supplements should be consumed. In some cases, iron and zinc status of vegans may also be of concern because of the limited bioavailability of these minerals.
Vegan diets are usually higher in dietary fiber, magnesium, folic acid, vitamins C and E, iron, and phytochemicals, and they tend to be lower in calories, saturated fat and cholesterol, long-chain n–3 (omega-3) fatty acids, vitamin D, calcium, zinc, and vitamin B-12 (8). In general, vegetarians typically enjoy a lower risk of cardiovascular disease (CVD), obesity, type 2 diabetes, and some cancers (3).
In summarizing the published research, Fraser (11) noted that, compared with other vegetarians, vegans are thinner, have lower total and LDL cholesterol, and modestly lower blood pressure.
A higher consumption of fruit and vegetables, which are rich in fiber, folic acid, antioxidants, and phytochemicals, is associated with lower blood cholesterol concentrations (17), a lower incidence of stroke, and a lower risk of mortality from stroke and ischemic heart disease
Vegans consume considerably more legumes, total fruit and vegetables, tomatoes, allium vegetables, fiber, and vitamin C than do omnivores (14–16, 20, 23). All those foods and nutrients are protective against cancer (25). Fruit and vegetables are described as protective against cancer of the lung, mouth, esophagus, and stomach and to a lesser degree some other sites, whereas the regular use of legumes provides a measure of protection against stomach and prostate cancer.
Red meat and processed meat consumption are consistently associated with an increase risk of colorectal cancer (). Those in the highest quintile of red meat intake had elevated risks, ranging from 20% to 60%, of esophageal, liver, colorectal, and lung cancers than did those in the lowest quintile of red meat intake (). In addition, the use of eggs was recently shown to be associated with a higher risk of pancreatic cancer
Data from the Adventist Health Study showed that consumption of soy milk by vegetarians protected them against prostate cancer (), whereas in other studies the use of dairy was associated with an increased risk of prostate cancer
To date, epidemiologic studies have not provided convincing evidence that a vegan diet provides significant protection against cancer.
Bone health depends on more than just protein and calcium intakes. Research has shown that bone health is also influenced by nutrients such as vitamin D, vitamin K, potassium, and magnesium and by foods such as soy and fruit and vegetables
Risk of hip fracture was decreased 45% for ≥1 servings/d of green leafy vegetables (the main vitamin K source) compared with ≤1 serving/wk (). In the Framingham Heart Study, elderly men and women in the highest quartile of vitamin K intake had a 65% decreased risk of hip fracture than did those in the lowest quartile
Diets that do not include fish, eggs, or sea vegetables (seaweeds) generally lack the long-chain n–3 fatty acids, eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3), which are important for cardiovascular health as well as eye and brain functions
Vegans should be able to easily reach the n–3 fatty acid requirements by including regular supplies of ALA-rich foods in their diet and also DHA-fortified foods and supplements
Compared with lactoovovegetarians and omnivores, vegans typically have lower plasma vitamin B-12 concentrations, higher prevalence of vitamin B-12 deficiency, and higher concentrations of plasma homocysteine