Vegetarian Diets

Description
A Vegetarian Diet is a variation of the Regular Diet in which certain or all foods of animal origin are excluded (1). A wide spectrum of dietary practices is considered vegetarian.

Lacto-ovovegetarian: Milk, milk products, and eggs are the only animal products included in the diet.
Lactovegetarian: Milk and milk products are the only foods of animal origin included in the diet.
Ovovegetarian: Eggs are the only animal product included in the diet.
Total vegetarian (vegan): The diet consists of foods of plant origin only.

Indications
Vegetarian diets are adopted for a variety of health, ecological, economical, philosophical, and ethical reasons (1). Vegetarian diets offer a number of advantages, including lower levels of saturated fat, cholesterol, and animal protein and higher levels of carbohydrates, fiber, magnesium, boron, folate, antioxidants (eg, vitamins C and E), carotenoids, and phytochemicals (1). Many epidemiologic studies suggest a positive relationship between vegetarian lifestyles and reduced risks of several chronic degenerative diseases, such as obesity, coronary artery disease, hypertension, type 2 diabetes, and some cancers. However, this relationship is likely due to lifestyle factors in addition to diet (1).

Nutritional Adequacy
Vegetarian diets are healthful and nutritionally adequate when appropriately planned (1). The diet can be planned to meet the Dietary Reference Intakes (DRIs) as outlined in the Statement on Nutritional Adequacy. Nutrients that are often of concern in vegans are vitamins B12 and D, calcium, zinc, and occasionally riboflavin and iron (1). All vegan children should have a reliable source of vitamin B12, and if sun exposure is limited, vitamin D supplements or fortified foods should be emphasized (1-4). Pregnant and lactating vegans should receive, respectively, supplements of 2 mg and 2.6 mg of vitamin B12 daily, and if sun exposure is limited, should have their diet supplemented with 10 mg of vitamin D (1). Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is necessary (1).

How to Order the Diet
Order as “Regular Diet – Vegetarian.” The patient’s particular dietary constraints will be considered.

Planning the Diet
A Vegetarian Diet can be made adequate by careful planning and by giving attention to the following guidelines (1):

In addition to these guidelines, refer to the Vegetarian Food Guide Pyramid (5) and Tips for Meal Planning in Table 1 (5).

Protein: Although vegetarian diets usually meet or exceed requirements for protein, they typically provide less protein than nonvegetarian diets. The body’s need for essential amino acids can be met by consumption of animal or plant sources of protein. Although plant foods contain less of the essential amino acids than do equivalent quantities of animal foods, a plant-based diet can provide adequate amounts of amino acids when a varied diet is consumed on a daily basis. A mixture of different proteins from unrefined grains, legumes, seeds, nuts, and vegetables will complement each other in their amino acid profiles to meet nutritional needs.

Different types of protein that complement each other should be eaten over the course of the day. However, since after absorption, amino acids from exogenous and endogenous sources combine in the body’s protein pool, it is not necessary that complementation of amino acid profiles be precise and present in the same meal (1). Isolated soy protein can meet protein needs as effectively as animal protein, whereas wheat protein eaten alone may be 50% less usable than animal protein (1). Cereals tend to be low in lysine, which is an essential amino acid; therefore, evaluating the sources of protein consumed in the diet is important to ensure adequacy (6).

Vitamin B12: Unless fortified, no plant food contains significant amounts of active vitamin B12. A vegan should supplement his or her diet with vitamin B12 by using a cobalamin supplement or by selecting fortified foods, such as fortified soy milk or breakfast cereals, to ensure an adequate intake of the active form of the nutrient. Although the requirement for vitamin B12 is relatively small, vegetarians must include a reliable source of vitamin B12 in their diets to reduce their risk of developing a deficiency. Supplements are advised for all vegetarians older than 50 years, because absorption of vitamin B12 becomes less efficient as the body ages (1). Also, breast-fed vegan infants should receive a source of vitamin B12 if the mother’s diet is not supplemented (7). If B12 foods are not consumed regularly (at least three servings per day), patients are advised to take a daily vitamin B12 supplement of 5 to 10 μg or a weekly B12 supplement of 2,000 μg (5).

Calcium: Calcium is present in many plant foods and fortified foods. The calcium intake of lactovegetarians is comparable to or higher than that of nonvegetarians (1). However, the calcium intake of vegans is generally lower than that of lactovegetarians and nonvegetarians and is often below recommended intakes (1). A diet that provides foods with relatively high ratios of sulfur-containing amino acid proteins (eg, eggs, meat, fish, poultry, dairy products, nuts, and many grains) may increase calcium loss from the bones (1). Excessive sodium intake may also promote calcium loss from the bones (1). Studies show that the ratio of dietary calcium to protein is more predictive of bone health than calcium intake alone (1). Typically, this ratio is high in lacto-ovovegetarian diets and favors bone health. However, vegan diets have calcium-to-protein ratios that are similar to or lower than those of nonvegetarian diets (8) If vegans do not meet calcium requirements from food, dietary supplements and fortified foods are recommended (1).

Vitamin D: Vitamin D status depends on sunlight exposure and intake of vitamin D–fortified foods or supplements. A vitamin D supplement may be necessary for persons, especially dark-skinned individuals, who do not ingest vitamin D–fortified milk products or cereals or do not obtain 5 to 15 minutes of exposure to sunlight daily (1,2). Vitamin D3 (cholecalciferol) is from an animal origin and may not be used by vegans. Vitamin D2 (ergocalciferol) is a form that may be used by vegans. Because the bioavailability of vitamin D2 is less than that of vitamin D3, vegetarians who depend on vitamin D2 supplements may have increased requirements (9).

Energy: Because vegan diets tend to be high in bulk, it can be challenging for vegans, especially infants, children, and adolescents, to meet their energy needs. Frequent meals and snacks and eating foods higher in fat can help vegetarian children meet their energy needs (1).

Iron: The non-heme iron found in plant foods is more sensitive than heme iron to both inhibitors and enhancers of iron absorption (1). The inhibitors of iron absorption include phytate, calcium, teas (including some herb teas), coffee, cocoa, some spices, and fiber (10). Western vegetarians have a relatively high intake of iron from plant foods, such as dark-green leafy vegetables, iron-fortified cereals, and whole grains. Although vegetarian diets are higher in total iron than nonvegetarian diets, iron stores are lower because iron from plant foods is not absorbed as well as iron from animal sources (1). However, the frequency of anemia is not higher in the vegetarian population than in the nonvegetarian population (1). The higher vitamin C intake of vegetarians may improve their iron absorption (1).

Zinc: Because phytate binds zinc, and animal protein is believed to enhance zinc absorption, total zinc bioavailability appears to be lower in vegetarian diets (11). Vegetarians should strive to meet or exceed the DRI for zinc due to the low bioavailability of zinc from plant sources and the high phytate content of a vegetarian diet (1).

N-3 fatty acids: Diets that do not include fish or eggs may lack the long-chain n-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (1). It has been shown that vegans have lower levels of DHA and EPA (1). Diets that do not include fish, eggs, or sea vegetables generally lack direct sources of DHA and EPA (1). It is recommended that vegetarians include good sources of alpha-linolenic acid, a precursor to DHA and EPA, in their diets. Good sources of alpha-linolenic acid include walnuts, flaxseed, flaxseed oil, and canola oil. Vegetarians with increased n-3 fatty acid requirements (eg, pregnant and lactating women) or with diseases, such as diabetes mellitus, associated with poor conversion may benefit from direct sources of long-chain n-3 fatty acids (eg, cod liver oil, mackerel, salmon, as well as crab, shrimp and oyster). Recently, DHA derived from microalgae has become available as a supplement in nongelatin capsules. Algae sources of DHA may be beneficial because they positively affect blood levels of DHA and of EPA (1,12-13).

Vegetarian Food Guide Pyramid
Adapted from: Messina V, Melina V, Mangels AR. A new food guide for North American vegetarians. J Am Diet Assoc. 2003;103:773.

1	Choose a variety of foods.
2	The number of servings in each group is the minimum daily intake. Choose additional foods from any groups to meet energy needs.
3	A serving from the calcium-rich food group provides approximately 10% of adult daily requirements. Choose eight or more servings per day. These also count towards servings from the other food groups in the guide. For example, ½ cup (120 mL) of fortified fruit juice counts as both a calcium-rich food and a serving from the fruit group.
4	Include two servings every day of foods that supply n-3 fatty acids. Foods rich in n-3 fatty acids are found in the legumes/nuts group and in the fats group. A serving is 1 tsp (5 mL) of flaxseed oil, 3 tsp (15 mL) of canola or soybean oil, 1 tbsp (15 mL) of ground flaxseed, or ¼ cup (60 mL) walnuts. For the best balance of fats in your diet, olive and canola oils are the best choices for cooking.
5	Servings of nuts and seeds may be used in place of servings from the fats group.
6	Be sure to get adequate vitamin D from daily sun exposure, fortified foods, or supplements. Cow’s milk and some brands of soy milk and breakfast cereals are fortified with vitamin D.
7	Include at least three servings every day of foods rich in vitamin B12. These include 1 tbsp (15 mL) of Red Star Vegetarian Support Formula nutritional yeast, 1 cup (240 mL) fortified soy milk, ½ cup (120 mL) cow’s milk, ¾ cup (180 mL) yogurt, one large egg, 1 oz of fortified breakfast cereal, or 1½ oz of fortified meat analogue. If you don’t eat these foods regularly (at least three servings per day), take a daily vitamin B12 supplement of 5 to 10 μg or a weekly B-12 supplement of 2,000 μg.
8	If you include sweets or alcohol in your diet, consume these foods in moderation. Get most of your daily calories from the foods in the Vegetarian Food Guide Pyramid.