Nutrition - A
Closer Look At Vegetarian Nutrition
By Cristina M. Caro, MBA, RD, LD
Vegetarian nutrition is in the spotlight more and more, especially as individuals look to holistic health and nutrition to prevent or treat chronic conditions and illnesses. Generally, healthcare practitioners caution patients about adopting restrictive diets. But a carefully planned vegetarian or vegan diet can provide adequate balance and variety to support good nutrition. Healthcare practitioners are in a position to inform patients of the potential pitfalls of an unbalanced diet and encourage careful menu planning and food preparation. This article will discuss the components of a vegetarian and vegan diet, the health considerations and reliable resources for vegetarian nutrition.
of a Vegetarian Diet
There are four types of vegetarian diets-all of which restrict flesh foods. They are essentially defined as such:
o The lacto-ovo-vegetarian avoids fish, fowl, and meat, but eats eggs and dairy products.
o The lacto-vegetarian avoids fish, fowl, meat and eggs, but consumes dairy products.
o The semi-vegetarian occasionally eats fish, fowl, and meat, but prefers plant-based meals.
o The vegan avoids all animal products and ingredients.
Despite the differences in dietary restrictions, all vegetarians can use the Vegetarian Food Guide Pyramid to plan a healthy diet that provides balance, variety and moderation. The Vegetarian Food Guide Pyramid is based on the U.S. Dietary Guidelines for Americans, but has been modified to include dairy and meat alternatives. Dairy substitutions include calcium-fortified juice, rice milk, soy cheese, soy ice cream, soymilk and soy yogurt. It is recommended that vegetarians consume 2-3 dairy or non-dairy alternatives per day in order to obtain adequate amounts of protein, calcium, and vitamins A, B12 and D.
Meat alternatives include beans, lentils, nuts, peas, seeds, seitan (made from wheat gluten), tempeh, textured vegetable protein and tofu. These foods provide a valuable source of calcium, iron, fiber, protein, vitamins B and E and zinc. It is recommended that vegetarians consume 2-3 meat alternatives per day.
Fruit and vegetable intakes should be 5-8 per day to provide significant amounts of fiber, vitamins and minerals. Cruciferous vegetables, such as broccoli, cabbage, cauliflower, chard and sprouts contain antioxidants believed to ward off cancers.
Grains consumed by vegetarians generally come from a wider variety of foods, such as barley, buckwheat, corn, couscous, granola, millet, oats, quinoa, pasta, rice and wheat. These foods provide excellent sources of B vitamins, fiber, minerals and protein. Recommendations for grains are 6-11 servings per day.
American Dietetic Association (ADA) suggests the following guidelines in planning
a vegetarian diet:
Choose a variety of foods among fruits, legumes, nuts, seeds, vegetables, whole grains and if desired, low-fat dairy products and eggs.
Minimize the intake of highly sweetened, fatty, and heavily refined foods.
Use a regular source of B-12, calcium, iron, omega-3 fatty acids, vitamin D (if sunlight exposure is limited) and zinc.
of a Vegetarian Diet
Fish, fowl and meat are major sources of protein, iron, zinc and B vitamins, and, therefore, are special health considerations for vegetarians (USDA 2000). All plant foods (except soy) possess incomplete proteins, which are missing one or more essential amino acids needed for protein metabolism. So, complementary proteins must be consumed within a 24-hour period to maintain an adequate nitrogen balance (ADA 2003). Complementary proteins are found in legumes, grains, nuts, seeds and vegetables. Scientific literature suggests that protein requirements for vegetarians may be 15-35 percent higher than requirements for non-vegetarians, due to the lower digestibility (Messina 2001). However, the Journal of the American Dietetic Association assures us that a vegetarian diet can meet the protein requirements of all vegetarians, with proper planning and preparation. Daily menus must also provide adequate calories for age, health status, and physical activity, to spare protein from being utilized for energy needs.
In addition to higher protein needs, vegetarians may require more iron and zinc than non-vegetarians (Hunt 2003). The iron present in plant foods is "nonheme," which has lower bioavailability than heme-iron from animal sources. Moreover, the fiber and phytates abundant in plant foods bind to iron and zinc and interfere with absorption. Accordingly, the ADA recommends that vegetarians consume 180 percent of the recommended daily allowance (RDA) for iron, to compensate for the lower bioavailability. Vegetarian iron sources include blackstrap molasses, bulgur, figs, leafy green vegetables, legumes, millet, raisins, tahini and tempeh. Additionally, vegetarians can enhance their iron absorption by consuming vitamin C-rich fruits and vegetables (bright orange, yellow, green and red) in the same meal as iron foods, to reduce the binding affects of fiber and phytates. Vegetarian diets can also provide adequate zinc levels, if a variety of grains, legumes and nuts are consumed.
The concern for B vitamins is significant, because animal products are the only food sources of vitamin B12. Lacto-vegetarians may obtain B12 from dairy products and eggs, but lacto-ovo vegetarians must take a B12 supplement or consume B12-fortified grains and meat analogs.
The nutritional adequacy of a vegetarian diet varies largely upon a person's age, food choices, health status and physical activity (ADA 2003). Notwithstanding, the U.S. Department of Agriculture's Continuing Survey of Food Intakes by Individuals (CSFII) suggests that vegetarians consume diet intakes consistent with dietary guidelines. And, although vegetarian diets are restrictive, current scientific knowledge purports they may improve health rather than cause disease (Sabate, 2003).
These food intake patterns are consistent with recommendations by the American Cancer Society, American Heart Association and National Institutes of Health. In fact, vegetarians in the United States have low rates of coronary disease, diabetes, obesity and many cancers (ADA, 2003).
Components of a Vegan
A vegan diet is the strictest of all vegetarian diets. No animal foods, byproducts or ingredients are allowed (i.e. albumin, casein, gelatin, honey, lard, whey). All food components must come from plant origin-fruits, grains, legumes, nuts, seeds and vegetables. Many vegans make their own foods to ensure quality and that the foods adhere to their dietary restrictions. Menu planning is essential to obtain adequate amounts of B12, calcium, vitamin D, and zinc, which would otherwise be obtained from animal sources. Vegan menus should include B12-fortified grains and meat analogs, as well as non-dairy calcium sources. Calcium may be obtained from almonds, blackstrap molasses, broccoli, dark leafy greens (i.e. beet greens, chard, collards, kale, spinach, rhubarb), and tahini. Keep in mind, however, that oxalic acid present in dark leafy greens, will bind with calcium and reduce absorption. Cooking the vegetables can reduce the binding effects of oxalic acid.
Vegans may need a vitamin D supplement, since few vegan foods are fortified vitamin D. However, 5-15 minutes of sunlight on the arms, face, and hands (without sunscreen) enables the body to produce cholecalciferol, which can be converted to calcitriol (active vitamin D) by the liver and kidneys (Groff, 2000). Zinc supplements are not recommended due the side effects associated with high doses (Duyff, 2002). Luckily, many plant foods (legumes, nut, seeds, tofu, unrefined grains) contain varying amounts zinc.
of a Vegan Diet
The additional restrictions of a vegan diet pose added nutritional risks of calcium, vitamin D, and B12 deficiencies. But, despite these pitfalls, vegans in the U.S. are rarely seen with clinical deficiencies (ADA 2003). Adequate intakes of B12, calcium, iron, and vitamin D may be obtained from fortified vegetarian foods, such as cereals, juices and soy products, and/or by vitamin and mineral supplements. Fortified foods and supplements free of animal products or ingredients are readily available in health food stores and supermarkets. So, the potential for nutritional risk lies only in unplanned vegan diets.
It is the position of the American Dietetic Association that "planned vegetarian (and vegan) diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases." Science has identified over 5,000 phytochemicals found in plants, including anthocyanins, flavenoids, isoflavones, polyphenols, sterols, and terpenes, to name a few (Sabate 2003). Numerous health studies have shown the cardio-protective qualities of isoflavones, which inhibit lipid peroxidation and reduce inflammation (Rajaram 2003). And Allicin, present in garlic, has demonstrated antimicrobial and antiviral properties. And let's not forget about polyphenols that help protect cells from oxidative damage. For these reasons and more, public health policy supports increased intakes of fruits and vegetables (Jenkins, 2003).
Vegetarian and vegan diets are abundant in antioxidant vitamins, fiber and phytochemicals, which help reduce risks for chronic disease. The observed benefits of long-term vegetarianism have positive health implications. Subsequently, healthcare practitioners have a responsibility to promote plant-based diets. Primary care providers can assist patients in obtaining information on vegetarian nutrition, foods, and resources, and make referrals to a registered dietitian (RD). These nutrition experts can prescribe individualized nutrition care plans and offer tips for vegetarian food purchasing and preparation, menu planning, dining out, and supplementation. Together, holistic health and nutrition can change the future health trends in America.
Cristina Caro, MBA, RD, LD, is co-owner of Medical Nutrition Therapy of Georgia and is an adjunct instructor for Life University's Department of Nutrition. This Georgia native serves on the Board of the Greater Atlanta Dietetic Association and participates in the Red Cross Disaster Action Team. Cristina was recognized by the Journal of the American Dietetic Association as Georgia's 2003 "Emerging Dietetics Leader" for her activities and leadership in the promotion of health and nutrition. Cristina has specialized training in clinical nutrition, child and adolescent weight management, food safety program management and health education. You may contact her via her website, www.mntofga.com.
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