Vegetarian DietManual of Clinical Nutrition Management A- 37 Copyright © 2013 Compass Group, Inc.
Minimize intake of foods that are highly sweetened, high in sodium, or high in fat, especially saturated fat and
trans fatty acids.
If animal foods such as dairy products and eggs are used, choose lower-fat dairy products and use both eggs
and dairy products in moderation.
Use a regular source of vitamin B 12 , and, if sunlight exposure is limited, provide a source of vitamin D.
In addition to these guidelines, the DRIs are a valuable resource for meal planning (1).
Protein: 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 energy needs are met and a varied
diet is consumed on a daily basis (1). Research indicates that an assortment of plant foods eaten over the course
of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults;
thus, complementary proteins do not need to be consumed at the same meal (1,8). 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. Estimates of protein requirements may vary based on dietary choices
selected, particularly for vegans. 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). Therefore, protein needs
might be somewhat higher than the Recommended Daily Allowance in those vegetarians whose dietary protein
sources are mainly those that are less well digested, such as some cereals and legumes (1,9). The consumption of
lysine, an essential amino acid, should be evaluated in persons who consume a vegan diet or who acquire a large
percentage of protein from cereal sources. Cereals tend to be low in lysine. Dietary adjustments, such as the use
of more beans and soy products in place of other protein sources that are lower in lysine or an increase in protein
from all sources, can ensure an adequate intake of lysine (1,10).
Vitamin B 12 : Unfortified plant foods do not contain significant amounts of active vitamin B 12. Although the
requirement for vitamin B 12 is relatively small, vegetarians must include a reliable source of vitamin B 12 in their
diets to reduce their risk of developing a deficiency. Lacto-ovovegetarians can obtain adequate vitamin B 12 from
the regular consumption of dairy foods, eggs, fortified foods, or supplements (1). Vegans should supplement their
diets with vitamin B 12 by selecting fortified foods, such as fortified soy or rice beverages, breakfast cereals, meat
analogs, or Red Star Vegetarian Support Formula nutritional yeast; otherwise, a daily vitamin B 12 supplement is
needed to ensure an adequate intake of the active form of the nutrient (1). Older adults who are vegetarian should
consume fortified foods or supplements to increase their vitamin B 12 intake, because the absorption of vitamin
B 12 often becomes less efficient in older adults due to atrophic gastritis (1). Also, breast-fed vegan infants should
receive a source of vitamin B 12 if the mother’s diet is not supplemented (1,4,10). If vitamin B 12 foods are not
consumed regularly (at least three servings per day), patients are advised to take a daily vitamin B 12 supplement
of 5 to 10 mcg or a weekly B 12 supplement of 2,000 mcg (11). Vitamin B 12 status is best determined by measuring
serum levels of homocysteine, methylmalonic acid, or holotranscobalamin II (1,12). Folacin-rich vegetarian diets
may mask the hematological symptoms of vitamin B 12 deficiency; therefore, a deficiency may go undetected until
the manifestation of neurological signs and symptoms (1,13).
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 the recommended level (1). In one
study, the risk of bone fracture was similar for lacto-ovovegetarians and meat eaters, whereas vegans had a 30%
higher risk of fracture possibly due to their considerably lower mean calcium intake (1,14). A diet that provides
foods with relatively high ratios of sulfur-containing amino acid proteins, such as 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 (1,15). Lower oxalate greens, such as bok choy, broccoli, Chinese cabbage, collards,
and kale, and fruit juices fortified with calcium citrate malate are good sources of highly bioavailable calcium
(50% to 60% and 40% to 50%, respectively), while calcium-set tofu, and cow’s milk have good bioavailability of
calcium (30% to 35%), and sesame seeds, almonds, and dried beans have a lower bioavailability (23% to 27%)
(1,15). Oxalates in some foods, such as spinach and Swiss chard, greatly reduce calcium absorption, making these
vegetables a poorer source of usable calcium (1). Foods rich in phytate may also inhibit calcium absorption (1). If
vegans do not meet calcium requirements from food, fortified foods and dietary supplements are recommended
(1).