Today, more and more dietitians are seeing vegetarian clients. Estimates of the number of vegetarians in the United States range from less than 1% to 4% of the population (1-4). The vast majority of vegetarians in this country eat dairy products and eggs; from 2% to 20% of U.S. vegetarians are vegans (4-6). A vegan (also called strict, pure, or total vegetarian) avoids all animal products.
Vegetarians seek nutrition counseling for a variety of reasons. These include a desire to improve an existing vegetarian diet, advice on the transition to a vegetarian diet, and modification of diet to prevent or treat an existing condition such as renal disease or diabetes. Non-vegetarians will seek help in including more plant-based foods. This review will focus on adult, non-pregnant vegetarians. Several publications provide sound advice for pregnant women (7-10) and infants and children (9-11) following vegetarian diets.
Dietary assessment is necessary to determine which foods are eliminated and what other foods are acceptable to supply those nutrients usually supplied by eliminated foods. Although many nutrition textbooks present terminology like "lacto-ovo vegetarian" and "vegan", in reality many vegetarians do not fall into a carefully defined category. Many individuals who would, strictly speaking, describe themselves as lacto-ovo vegetarians, actually use dairy products and eggs on a very sporadic basis. Some individuals who claim to follow vegetarian diets simply mean that they avoid red meat or only eat fish and in reality are not vegetarians. Table 1 provides information on assessment of vegetarians.
The traditional four food groups or the food guide pyramid are not effective tools for assessment of adequacy of a vegetarian diet. These tools were designed for those eating typical American diets. A thorough diet history followed by analysis for calories and key nutrients such as iron, calcium, and vitamin B12 provides a more reliable picture of a vegetarian client's diet. Computer nutrient databases are including many more vegetarian foods; however, they may overestimate cholesterol intake of vegans because nutrient tables assume that baked products are prepared with eggs and dairy products (12). Supplemental information can be obtained from published articles on nutrient content of vegetarian foods (13,14) and from food labels. Food guides have been developed specifically for vegetarians (15-18) and these provide another option for dietary assessment and can be useful in counseling.
Johnston has developed guidelines for counseling pregnant vegetarians (7) which are quite useful in working with any vegetarian. She emphasizes 1) establishing rapport, 2)reinforcing positive nutrition practices, 3) prioritizing nutritional concerns to help the client choose appropriate dietary changes, and 4) individualizing counsel. Adaptability and creativity are essential in developing meal plans which are acceptable to vegetarians (18). It is important to remember that nutritional requirements are for essential nutrients not for specific foods.
Some vegetarians, like some omnivores, find selection of a varied diet to be difficult. Factors such as lack of knowledge of food preparation, lack of time, and economic constraints may lead to a monotonous diet. Basic vegetarian cookbooks can be used to provide ideas for increased dietary variety. Tours of supermarkets or natural food stores will illustrate the many products which are suitable for use by vegetarians. Vegetarian cooking classes are a great way for people to learn about how to use a variety of fruits, vegetables, legumes and whole grains.
Vegetarians may seek advice about calcium and iron. In general, calcium intakes and status of vegetarians using dairy products are similar to the general population (25, 26). Vegans will need to rely on non-dairy calcium sources such as low-oxalate leafy green vegetables (e.g. kale, broccoli, mustard, collard, and turnip greens), tofu processed with calcium sulfate, fortified juices and soy drinks, oranges, almonds, figs and blackstrap molasses (11, 14, 27). Generous daily use of these foods can supply adequate calcium. Calcium supplements represent another alternative. A concern is often expressed about plant constituents which inhibit calcium absorption. Calcium from low-oxalate green vegetables has been shown to be absorbed as well or better than calcium from cow's milk (27). Lifestyle aspects such as lower but adequate protein intakes by vegans (28, 29) and regular weight bearing exercise may offer some protection against development of osteoporosis in later life (30-32).
Vegetarians are not at greater risk for iron deficiency than non-vegetarians (24). Good sources of iron for vegetarians include whole-grain and fortified cereals, legumes, dark green vegetables, nuts, seeds, and dried fruits (33). Absorption of non-heme iron, as found in plant foods, is enhanced by simultaneous consumption of ascorbic acid (34) or other acids found in fruits and vegetables (33). Cooking in iron cookware also adds to iron intake(35).
Vegetarians who do not use animal products need a reliable source of vitamin B12 since it is not synthesized by any plant. A variety of products including tempeh, miso, spirulina, and sea vegetables have been suggested as sources of vitamin B12. These products are not reliable sources (36, 37) unless vitamin B12 has been added during processing. Reliable sources of vitamin B12 include B12-fortified cereals and soymilks and fortified nutritional yeast . Vitamin B12 supplements are acceptable to some vegans. Lacto-ovo and lacto vegetarians will get adequate amounts of vitamin B12 from dairy products and eggs (38). If non-vegans develop a vitamin B12 deficiency, the cause of decreased absorption should be investigated (38).
Most vegetarian diets consisting of a variety of foods and containing sufficient calories to meet energy needs are adequate in protein (24). All too often vegetarians are presented with charts and tables describing how to carefully combine proteins to meet protein requirements. This sort of conscious combining within a given meal is unnecessary (39) and should not be stressed as it may make a vegetarian diet seem much more complicated than it needs to be.
Vegetarians or the general public may seek advice on the use of soy foods. Recent research has centered on the role of soybean phytoestrogens called isoflavones in cancer prevention. Populations consuming high levels of isoflavones have low rates of breast cancer (40, 41). In addition, high soy food consumption is associated with lower rates of many cancers including breast, colon, and prostate (42-44). Soy products also appear to be helpful in reduction of mildly elevated blood cholesterol levels (45). Table 2 provides definitions of soy foods and suggestions for their use.
New vegetarians are frequently looking for practical advice. Several groups have published food guides and sample menus (15-18) which can be very helpful to new vegetarians.
New vegetarians may be concerned with making the transition to vegetarianism. There are no rules for this. Some people have been very successful at giving up meat, fish, and poultry overnight while others make a more gradual change. Regardless, dietary variety and adequacy should be stressed.
Increased flatulence or bloating due to higher fiber and bean intakes may be experienced by new vegetarians. Suggestions for dealing with this include gradual increase in the amount of fiber and beans eaten; thorough cooking of beans; and use of products which are generally considered more digestible such as tempeh, tofu, adzuki beans, split peas, and lentils (46).
Limited information is available on modification of therapeutic diets to accommodate a vegetarian lifestyle. The Vegetarian Nutrition DPG is working with other DPGs to develop tools for vegetarians on modified diets. The diet manual developed by the Seventh-day Adventist Dietetic Association (51) is an excellent resource. With creativity and knowledge of vegetarian diets it is possible to develop modified diets which are acceptable to vegetarians.
Numerous studies have demonstrated that adults following vegetarian diets have reduced risk of several chronic degenerative diseases including obesity, cardiovascular disease, hypertension, diabetes mellitus, and certain cancers (47-49).
Vegan diets tend to be lower in fat, saturated fat and cholesterol, and higher in fiber than the diet of the general US population (12, 19-22). Such a diet can be beneficial in control of hypercholesterolemia. Over-reliance on eggs and high-fat dairy products by lacto-ovo vegetarians can lead to diets which are higher in fat than omnivorous diets (23). Lacto-ovo vegetarians should use low-fat or nonfat dairy products and limit egg intake to 3-4 yolks per week (24). The consumption of high fat plant products like oil, nuts, nut butters, avocado, and margarine should be assessed and recommendations made.
Ornish and co-workers (50) successfully treated patients with severe coronary artery disease with a low-fat vegetarian diet (10% fat, 15-20% protein, 70-75% primarily complex carbohydrates) including vegetables, grains, legumes, soyfoods, egg whites, and one cup per day of non-fat dairy products. The very low fat vegetarian diet was given in conjunction with smoking cessation, stress management. Subjects reported reduced frequency, severity and duration of angina and had a regression in arterial stenosis. This type of diet appears to be more effective than conventional recommendations (50).
Vegetarians have been found to have lower blood pressure than non-vegetarians (23, 52-55). A vegetarian diet has been successfully used as treatment for mild hypertension (56). In counseling a hypertensive vegetarian, one can emphasize the same recommendations to reduce dietary sodium and promote weight loss, if needed, as would be used with a non-vegetarian. Vegetarians often find it easy to achieve increased dietary potassium, magnesium, and calcium and reduced saturated fat. These dietary components may aid in control of high blood pressure (57).
Many dietitians have successfully developed meal plans for use with clients with renal disease. Eggs, low sodium cheese, tofu, and unsalted peanut butter can replace meat in renal diets although the high potassium content of peanut butter should be considered (51). Dairy products, eggs, and soyfoods are sources of protein of high biologic value. Some authorities recommend that in renal disease, at least 70% of protein should be of high biologic value to aid in control of serum urea nitrogen (57).
Dried beans can supply additional protein and calories. They tend to be high in potassium but can be accommodated by counting them as a combination of bread and vegetable groups (51).
An intriguing study suggested that soy products may be beneficial in renal disease. Individuals with hyperlipidemia and nephrotic syndrome were placed on a vegetarian diet containing soy products. Proteinuria decreased as did blood cholesterol levels (58).
Although vegetarians as a group tend to be leaner than non-vegetarians (23, 59, 60), obesity does occur in some vegetarians. A reduction in dietary fat may be effective in promoting weight loss (61-63) in conjunction with a regular exercise program. Meal plans or exchange lists emphasizing lowfat vegetarian foods and moderate calorie restriction (64) can be useful tools.
New recommendations for diabetes management (65-66) are supportive of vegetarian diets in that they stress an individualized approach adjusted for the personal lifestyle and diabetes management goals of an individual. For those with type II diabetes, a reduction in total dietary fat and saturated fat is emphasized to help in achievement of optimal serum lipid levels. Approximately 10 to 20% of daily caloric intake should be from protein (65-66). Due to lower digestibility of plant proteins (34), if dietary protein is primarily from grains, beans, and vegetables, protein intake should be higher than 10% of calories
Persons with diabetes should be encouraged to increase their dietary fiber intake, particularly soluble fiber, to aid in blood glucose and lipid control. Dietary fiber levels of at least 25-30 gms daily are recommended (65-67). Vegetarian diets typically are high in fiber (12, 22, 68). Good sources of fiber include beans, whole grains, vegetables, and fruit.
Although many other techniques are being developed, many persons with diabetes are familiar with exchange lists. The exchange lists (69) are usable by lacto-ovo-vegetarians. Vegans with diabetes who wish to use exchange lists will need additional counseling. Exchange lists which include foods commonly eaten by vegetarians have been developed (64). Messina recommends that vegans either choose milk alternatives such as soy milk or follow a meal plan which does not include the milk group but includes alternative sources of calcium (64).
Working with vegetarians presents an interesting challenge. Creativity and openness to new ideas are essential.
Vegetarian Nutrition is a dietetic practice group of the American Dietetic Association. Copyright © 2008 VNDPG/American Dietetic Association. VN/ADA does not endorse the content, products, or services on other websites. Please contact us if you have any questions. For technical assistance with vegetariannutrition.net, please contact the .