Vegetarian diets given a clean bill of health

Official recognition of the nutritional adequacy and potential health benefits of vegetarian diets was provided in a paper published in the June 2003 issue of the prestigious Journal of the American Dietetic Association (Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets, J Am Diet Assoc 2003;103:748-765). The paper includes the following position statement:

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases.

Authors Ann Reed Mangels, Virginia Messina and Vesanto Melina review the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, omega-3 fatty acids, and iodine, and conclude that a vegetarian or vegan diet can meet current recommended intakes of all of these nutrients. Further,

Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than non-vegetarians, as well as lower rates of death from ischaemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.

The term “well-planned” is especially significant. Vegetarian diets are not a panacea, and there have been some well-documented examples of vegetarians and vegans suffering serious illness as a consequence of inadequate intakes of key vitamins and minerals. The position paper recognises this, and lists food sources of iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12 and linolenic acid (an omega-3 fatty acid) that are suitable for vegetarians and vegans. Vitamin B-12 can be especially problematic as the only reliable sources for vegans are either fortified foods or dietary supplements. Indeed, because 10% to 30% of persons over the age of 50 lose the ability to digest the form of this vitamin found in animal products it is recommended that all persons aged 50 or over use B-12 supplements or fortified foods (including some soya ‘milks’, yeast extracts and breakfast cereals). Low vitamin B-12 intake raises plasma homocysteine concentration which is associated with increased heart disease risk, and prolonged deficiency may lead to impaired neurological function and megaloblastic anaemia, so it is essential to ensure adequate intake of this vitamin. The UK Vegan Society recommends consuming at least three micrograms of vitamin B-12 per day, and they have a useful information sheet on the subject on their web site at www.vegansociety.com.

The same authors set out their recommendations for a healthy vegetarian/vegan diet in an accompanying paper (A new food guide for North American vegetarians, J Am Diet Assoc 2003;103:771-775). The paper presents a vegetarian food guide pyramid with foods forming the basis of a healthy diet at the base of the pyramid and foods required in smaller quantities at the top of the pyramid. Reading upwards from the base of the pyramid, a healthy vegetarian or vegan diet should include a minimum of 6 servings (portions) of grains (preferably whole grains), 5 servings of legumes, nuts and other protein-rich foods, 4 servings of vegetables, 2 servings of fruit, and 2 servings of fats rich in omega-3 fatty acids per day, with extra servings from any group added as required to meet energy needs. The authors also recommend consuming 8 or more servings of calcium-rich foods per day as part of the diet, listing suitable choices, and provide a list of helpful tips for meal planning.

Both the position paper and the food guide can be accessed on the internet at http://www.webdietitians.org/Public/GovernmentAffairs/92_10575.cfm

Paul Appleby, June 2003

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This page created 29 June 2003 and updated 31 May 2004 by Paul Appleby.