This American Dietetic Association (ADA) position paper includes the authors’ independent review of the literature in addition to systematic review conducted using the ADA’s Evidence Analysis Process and information from the Evidence Analysis Library. [...] The use of an evidence-based approach provides important added benefits to earlier review methods. The major advantage of the approach is the more rigorous standardization of review criteria, which minimizes the likelihood of reviewer bias and increases the ease with which disparate articles may be compared.
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes. A vegetarian diet is defined as one that does not include meat (including fowl) or seafood, or products containing those foods. This article reviews the current data related to key nutrients for vegetarians including protein, n-3 fatty acids, →iron, →zinc, iodine, →calcium, and vitamins D and B-12. A vegetarian diet can meet current recommendations for all of these nutrients. In some cases, supplements or fortified foods can provide useful amounts of important nutrients. An evidence-based review showed that vegetarian diets can be nutritionally adequate in pregnancy and result in positive maternal and infant health outcomes. The results of an evidence-based review showed that a vegetarian diet is associated with a lower risk of death from ischemic heart disease. Vegetarians also appear to have lower low-density lipoprotein cholesterol levels, lower blood pressure, and lower rates of hypertension and type 2 diabetes than nonvegetarians. Furthermore, vegetarians tend to have a lower body mass index and lower overall cancer rates. Features of a vegetarian diet that may reduce risk of chronic disease include lower intakes of saturated fat and cholesterol and higher intakes of fruits, vegetables, whole grains, nuts, soy products, fiber, and phytochemicals. The variability of dietary practices among vegetarians makes individual assessment of dietary adequacy essential. In addition to assessing dietary adequacy, food and nutrition professionals can also play key roles in educating vegetarians about sources of specific nutrients, food purchase and preparation, and dietary modifications to meet their needs. J Am Diet Assoc. 2009;109: 1266-1282.
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the lifecycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.
Vegetarian Diets in Perspective
A vegetarian is a person who does not eat meat (including fowl) or seafood, or products containing these foods. The eating patterns of vegetarians may vary considerably. The lacto-ovovegetarian eating pattern is based on grains, vegetables, fruits, legumes, seeds, nuts, dairy products, and eggs. The lacto-vegetarian excludes eggs as well as meat, fish, and fowl. The vegan, or total vegetarian, eating pattern excludes eggs, dairy, and other animal products. Even within these patterns, considerable variation may exist in the extent to which animal products are excluded.
EAL Conclusion Statement: The two most common ways of defining vegetarian diets in the research are vegan diets: Diets devoid of all flesh foods; and vegetarian diets: Diets devoid of all flesh foods, but also include egg (ovo) and/or dairy (lacto) products.
However, these very broad categories mask important variations within vegetarian diets and dietary practices. These variations within vegetarian diets make absolute categorization of vegetarian dietary practices difficult and may be one of the sources of unclear relationships between vegetarian diets and other factors. [...]
In this article, the term vegetarian will be used to refer to people choosing a lacto-ovo-, lacto-, or vegan vegetarian diet unless otherwise specified. Whereas lacto-ovo-, lacto-, and vegan-vegetarian diets are those most commonly studied, practitioners may encounter other types of vegetarian or near-vegetarian diets. For example, people choosing macrobiotic diets typically describe their diet as vegetarian. The macrobiotic diet is based largely on grains, legumes, and vegetables. Fruits, nuts, and seeds are used to a lesser extent. Some people following a macrobiotic diet are not truly vegetarian because they eat limited amounts of fish. The traditional Asian-Indian diet is predominantly plant based and is frequently lacto-vegetarian although changes often occur with acculturation, including greater consumption of cheese and a movement away from a vegetarian diet. A raw foods diet may be a vegan diet, consisting mainly or exclusively of uncooked and unprocessed foods. Foods used include fruits, vegetables, nuts, seeds, and sprouted grains and beans; in rare instances unpasteurized dairy products and even raw meat and fish may be used. Fruitarian diets are vegan diets based on fruits, nuts, and seeds. Vegetables that are classified botanically as fruits like avocado and tomatoes are commonly included in fruitarian diets; other vegetables, grains, beans, and animal products are excluded.
Some people will describe themselves as vegetarian but will eat fish, chicken, or even meat. These self-described vegetarians may be identified in research studies as ↑semivegetarians. Individual assessment is required to accurately evaluate the nutritional quality of the diet of a vegetarian or a self-described vegetarian.
In 2006, based on a nationwide poll, approximately 2.3% of the US adult population (4.9 million people) consistently followed a vegetarian diet, stating that they never ate meat, fish, or poultry [...]. About 1.4% of the US adult population was vegan [...]. In 2005, according to a nationwide poll, 3% of 8- to 18-year-old children and adolescents were vegetarian; close to 1% were vegan [...].
New Product Availability
The US market for processed vegetarian foods (foods like meat analogs, nondairy milks, and vegetarian entrees that directly replace meat or other animal products) was estimated to be $1.17 billion in 2006 [...]. This market is forecast to grow to $1.6 billion by 2011 [...].
The availability of new products, including fortified foods and convenience foods, would be expected to have an impact on the nutrient intake of vegetarians who choose to eat these foods. Fortified foods such as soy milks, meat analogs, juices, and breakfast cereals are continually being added to the marketplace with new levels of fortification. These products and dietary supplements, which are widely available in supermarkets and natural foods stores, can add substantially to vegetarians’ intakes of key nutrients such as →calcium, →iron, →zinc, →vitamin B12, →vitamin D, riboflavin, and long-chain n-3 fatty acids. With so many fortified products available today, the nutritional status of the typical vegetarian today would be expected to be greatly improved from that of a vegetarian 1 to 2 decades ago. This improvement would be enhanced by the greater awareness among the vegetarian population of what constitutes a balanced vegetarian diet. Consequently older research data may not represent the nutritional status of present-day vegetarians.
Health Implications of Vegetarian Diets
Vegetarian diets are often associated with a number of health advantages, including lower blood cholesterol levels, lower risk of heart disease, lower blood pressure levels, and lower risk of hypertension and type 2 diabetes. Vegetarians tend to have a lower body mass index (BMI) and lower overall cancer rates. Vegetarian diets tend to be lower in saturated fat and cholesterol, and have higher levels of dietary fiber, magnesium and potassium, vitamins C and E, →folate, carotenoids, flavonoids, and other phytochemicals. These nutritional differences may explain some of the health advantages of those following a varied, balanced vegetarian diet. However, vegans and some other vegetarians may have lower intakes of →vitamin B12, →calcium, →vitamin D, →zinc, and long-chain n-3 fatty acids.
Vegetarian Diets Throughot the Life Cycle
Well-planned vegan, lacto-vegetarian, and lacto-ovo-vegetarian diets are appropriate for all stages of the life cycle, including pregnancy and lactation. Appropriately planned vegan, lacto-vegetarian, and lacto-ovo-vegetarian diets satisfy nutrient needs of infants, children, and adolescents and promote normal growth [...].
A variety of menu planning approaches can provide adequate nutrition for veg[...]ans. The Dietary Reference Intakes are a valuable resource for food and nutrition professionals. Various food guides [...] can be used [...]. In addition, the following guidelines can help veg[...]ans plan healthful diets:
Choose a variety of foods, including whole grains, vegetables, fruits, legumes, nuts, seeds [...].
Minimize intake of foods that are highly sweetened, high in sodium, and high in fat, especially saturated fat and trans-fatty acids.
Figure 1. Suggestions for planning veg[...]an meals.
Figure 1 provides specific suggestions for meal planning for vegetarian diets. Lifelong vegetarians have adult height, weight, and BMIs that are similar to those who became vegetarian later in life, suggesting that well-planned vegetarian diets in infancy and childhood do not affect final adult height or weight [...]. Vegetarian diets in childhood and adolescence can aid in the establishment of lifelong healthful eating patterns and can offer some important nutritional advantages. Vegetarian children and adolescents have lower intakes of cholesterol, saturated fat, and total fat and higher intakes of fruits, vegetables, and fiber than nonvegetarians [...]. Vegetarian children have also been reported to be leaner and to have lower serum cholesterol levels [...].
Pregnant and Lactating Women
The nutrient and energy needs of pregnant and lactating vegetarian women do not differ from those of nonvegetarian women with the exception of higher →iron recommendations for vegetarians. Vegetarian diets can be planned to meet the nutrient needs of pregnant and lactating women.
Growth of young vegetarian infants receiving adequate amounts of breast milk or commercial infant formula is normal. When solid foods are introduced, provision of good sources of energy and nutrients can ensure normal growth. The safety of extremely restrictive diets such as fruitarian and raw foods diets has not been studied in children. These diets can be very low in energy, protein, some vitamins, and some minerals and cannot be recommended for infants and children.
Breastfeeding is common in vegetarian women, and this practice should be supported. The breast milk of vegetarian women is similar in composition to that of nonvegetarians and is nutritionally adequate.
Soy formula is the only option for nonbreastfed vegan infants. Other preparations including soymik, rice milk, and homemade formulas should not be used to replace breast milk or commercial infant formula.
Solid foods should be introduced in the same progression as for nonvegetarian infants, replacing strained meat with mashed or pureed tofu, legumes (pureed and strained if necessary), soy [...] yogurt [...]. Later, around 7 to 10 months, foods such as cubed tofu, [...] or soy cheese and bite-size pieces of veggie burgers can be started. Commercial, [...] fortified soy milk [...] can be used as a primary beverage starting at age 1 year or older for a child who is growing normally and eating a variety of foods [...]. Foods that are rich in energy and nutrients such as legume spreads, tofu, and mashed avocado should be used when the infant is being weaned.
Guidelines for dietary supplements generally follow those for nonvegetarian infants. Breastfed infants whose mothers do not have an adequate intake of →vitamin B12 should receive a →vitamin B12 supplement [...]. →zinc intake should be assessed and →zinc supplements or →zinc-fortified foods used when complementary foods are introduced if the diet is low in →zinc or mainly consists of foods with low →zinc bioavailability [...].
Growth of lacto-ovo-vegetarian children is similar to that of their nonvegetarian peers [...]. Little information about the growth of nonmacrobiotic vegan children has been published. Some studies suggest that vegan children tend to be slightly smaller but within the normal ranges of the standards for weight and height [...]. Poor growth in children has primarily been seen in those on very restricted diets [...].
Frequent meals and snacks and the use of some refined foods (such as fortified breakfast cereals, breads, and pasta) and foods higher in unsaturated fats can help vegetarian children meet energy and nutrient needs. Average protein intakes of vegetarian children (lacto-ovo, vegan, and macrobiotic) generally meet or exceed recommendations [...].
Growth of lacto-ovo-vegetarian and nonvegetarian adolescents is similar [...]. Earlier studies suggest that vegetarian girls reach menarche slightly later than nonvegetarians [...]; more recent studies find no difference in age at menarche [...].
Vegetarian diets appear to offer some nutritional advantages for adolescents. Vegetarian adolescents are reported to consume more fiber, →iron, →folate, vitamin A, and vitamin C than nonvegetarians [...]. Vegetarian adolescents also consume more fruits and vegetables, and fewer sweets, fast foods, and salty snacks compared to nonvegetarian adolescents [...]. Key nutrients of concern for adolescent vegetarians include →calcium, →vitamin D, →iron, →zinc, and →vitamin B12.
Being vegetarian does not cause disordered eating as some have suggested although a vegetarian diet may be selected to camouflage an existing eating disorder [...]. Because of this, vegetarian diets are somewhat more common among adolescents with eating disorders than in the general adolescent population [...].
With aging, energy needs decrease but recommendations for several nutrients, including →calcium, →vitamin D, and vitamin B-6 are higher. Intakes of micronutrients, especially →calcium, →zinc, →iron, and →vitamin B12, decline in older adults [...].
Older adults may have difficulty with →vitamin B12 absorption from food, frequently due to atrophic gastritis, so →vitamin B12-fortified foods or supplements should be used because the →vitamin B12 in fortified foods and supplements is usually well-absorbed [...].
Vegetarian diets can also meet the needs of competitive athletes. Nutrition recommendations for vegetarian athletes should be formulated with consideration of the effects of both vegetarian diets and exercise. The position of American Dietetic Association and Dietitians of Canada on nutrition and athletic performance provides additional information specific to vegetarian athletes [...].
Appropriately planned vegetarian diets have been shown to be healthful, nutritionally adequate, and may be beneficial in the prevention and treatment of certain diseases. Vegetarian diets are appropriate for all stages of the life cycle. There are many reasons for the rising interest in vegetarian diets. The number of vegetarians in the United States is expected to increase during the next decade.
Quelle: Journal of the American Dietetic Association, "Position of the American Dietetic Association: Vegetarian Diets", July 2009 Volume 109 Number 7 (J Am Diet Assoc. 2009;109: 1266-1282.)