Vegetarianism describes the diet (eg, green vegetables, cereals, seeds, fruit and nuts, roots and perhaps eggs and dairy products) of those who abstain from food of animal sources. Many Canadians have chosen a vegetarian diet for economic, religious, moral or health reasons. Semivegetarians have eliminated only red meat from their diet and may substitute for it poultry, fish, milk or eggs. Those who eat no meat are called "lacto-ovo" (milk and eggs) vegetarians. "Lacto vegetarians" eliminate eggs and meat, while "ovo vegetarians" consume eggs, but no milk products or meat. The total, pure, or strict vegetarian, referred to as a "vegan," will consume only plant foods and not any animal products. Even more restrictive are the "fruitarians," who consume only fruit, nuts, honey and olive oil. An extreme form of cult vegetarianism referred to as the Zen macrobiotic diet eliminates all foods except for brown rice in the final stage of the dietary regimen.
Risk of Nutrient Deficiencies
When a source of complete protein is accepted (eg, milk, eggs, fish), it is relatively easy to plan a nutritionally adequate diet. However, with greater restriction on the variety of foods, it becomes increasingly difficult to meet nutrient needs, and the risk of nutrient deficiencies becomes more prevalent. Because of these risks careful attention to the planning of the diet is recommended, and the advice of a registered dietician may be beneficial (see DIETETICS). Nutrients of particular concern for those eliminating all animal sources are protein, calcium, iron, zinc, vitamin B12, vitamin D and riboflavin (vitamin B2). These nutritional concerns can be of even greater significance in pregnant and lactating women, infants and children, adolescents and those with underlying chronic disease.
Because of the importance of protein in growth repair and maintenance of optimal health, this nutrient is of primary importance to the vegetarian. A single plant source cannot provide complete protein as animal sources do. However, specific combinations of different plant foods can provide all of the essential amino acids. Three combinations in the appropriate quantities that will achieve this are grains and legumes, grains and milk products, or seed and legumes. In addition, the vegetarian must take care to ensure that the recommended nutrient intakes of the at-risk vitamins and minerals are consumed.
Despite these concerns, vegetarian diets have been associated with a variety of health benefits, including reduced risk of high blood pressure, elevated lipid levels, coronary heart disease, obesity, osteoporosis and some cancers.