Vegetarians can rest assured. Plant-based foods are loaded with nutrients including ample protein, iron, calcium, vitamin D, iodine, omega-3 fatty acids, and zinc. Vegans require a reliable source of vitamin B12.
Whether you eat a vegetarian or non-vegetarian diet, the key to health is simple. Include a wide variety of different foods in your diet – no one food source is nutritionally complete by itself. Vegetarians choose foods from grains, vegetables, legumes, nuts, seeds and fruits. Whole unrefined foods are best. Eggs and dairy are optional. On a plant-based diet, you will have the distinct advantage of obtaining nutrients from sources high in fibre, and low in saturated fat and cholesterol.
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It was once thought that foods had to be combined within a single meal to provide complete protein. The latest research indicates that an assortment of plant foods eaten over the course of a day can provide all of the essential amino acids you need. This is the postion of the Dietitians of Canada and the American Dietetic Association. Most people can easily meet their protein needs by eating a variety of whole grains, legumes, and vegetables on a daily basis. Although there is somewhat less protein in a vegetarian diet, this is actually an advantage, as excess protein has been linked to heart disease, cancer, kidney disease and osteoporosis. Foods high in protein include tofu, tempeh, TVP, beans, nuts, seeds, soy milk, some vegetables (such as broccoli, asparagus, spinach, snowpeas, Brussels sprouts).
The American Dietetic Association’s Position Paper on Vegetarian Diets says, “Incidence of iron deficiency anemia among vegetarians is similar to that of non-vegetarians. Although vegetarian adults have lower iron stores than non-vegetarians, their serum ferritin levels are usually within the normal range.”
The richest plant sources of iron are fortified breakfast cereals, soy products and legumes, whole grains, dark green vegetables, dried fruits, nuts and seeds, potato with skin, and blackstrap molasses. Cooking with cast-iron pots(especially water based acidic foods like tomato sauce) also contributes to dietary intake. Adding fruits and vegetables high in vitamin C (ascorbic acid) to your meals (such as citrus, peppers, cabbage, broccoli, tomatoes, and greens like kale and collards) enhances iron absorption. The same is true for other organic acids in fruits and vegetables. Calcium supplements, black or green tea, coffee and chocolate inhibit iron absorption if eaten at the same time as iron. Dairy products contain very little iron.
Only about one fifth of the iron in a standard diet comes from meat, but plants contain non-heme iron which is not as easily absorbed as the heme iron that makes up two thirds of the iron in meat. Because of this the RDA for iron has been set higher for vegetarians. In Canada and the US it is 33 mg per day for vegetarian women verses 18 mg per day for meat-eating women. For meat-eating men and postmenopausal women it is 8 mg of iron a day, but for vegetarians in this group it is 14 mg. According to Jack Norris, RD, this is controversial because the recommendations were not based on studies of vegetarians, but instead on vegetarian diets designed to reduce iron absorption. The RDAs for vegetarians don’t properly take into account the benefits of adding vitamin C and avoiding tea and coffee at meals. Also, Norris has observed that some women have trouble getting enough iron on a vegetarian diet initially, but over time their bodies become efficient at absorbing non-heme iron. Due to blood loss during menstruation, iron deficiency anemia is more of a concern for adult women than it is for men.
There are some advantages to having a lower iron intake: Lower iron levels are associated with higher glucose tolerance and might help prevent diabetes, and high iron levels have been linked to cancer.
Calcium needs can also be met on a well-planned vegan diet without resorting to dairy products. Rich plant food sources include dark green vegetables such as broccoli, bok choy and kale, beans, tofu (made with calcium), tahini, sesame seeds, almonds, figs, seaweeds, unrefined molasses, and fortified soy milks. Since the consumption of animal protein increases calcium requirements, a person following a vegan diet may have much lower needs. Although some plant foods contain oxalates and phytate which can inhibit calcium absorption, the calcium in plant foods is generally well absorbed.
This vitamin is essential for the absorption of calcium and is formed in the presence of direct or indirect sunlight. Your body stores vitamin D during the summer for winter use. On average, about 10 to 15 minutes a day of sun on the face and hands for light-skinned people should suffice. Darker-skinned people, the elderly, and those at higher latitudes may need more sun exposure. Sunscreen lotion rated SPF 8 or above prevents vitamin D synthesis. Some rice and soy milks are fortified with vitamin D. People getting insufficient sun or not eating fortified foods should consider taking a daily multiple vitamin that includes 400 IU of vitamin D.
Zinc is readily available in many plant foods such as whole grains (breads, pasta, rice), wheat germ, tofu, tempeh, millet, quinoa, miso, legumes, sprouts, nuts and seeds.
Very low B12 intakes can cause anemia and nervous system damage. Meat-eaters acquire B12 through micro-organisms living in the animal flesh they eat. Lacto-ovo vegetarians receive B12 through eggs and dairy products.
The only reliable vegan sources are foods fortified with B12 (including some rice and soy milks, some breakfast cereals, and Red Star nutritional yeast vegetarian support formula), B12 supplements and some multi-vitamins. In the past some non-animal items such as spirulina, tempeh, miso, and soil were considered as possible sources, but these have proven to be unreliable.
In the absence of any apparent dietary supply, deficiency symptoms usually take five years or more to develop in adults, though some people experience problems within a year. Long term studies of vegans have detected a very low rate of B12 deficiency. Some people (including meat-eaters) have problems absorbing B12. It’s especially important for women to ensure B12 intake when pregnant or breastfeeding.
Regular iodized table salt is fortified with plenty of iodine, but if you use sea salt instead, be sure your diet includes a reliable source. Sea salt contains very little iodine. The best sources are seaweed, vegetables grown near the ocean, and many vitamin and mineral supplements. Also some breads use dough stabilizers that contain iodine. Iodine is needed for the normal metabolism of cells.
Omega-3 fatty acids
Omega-3 fatty acids include ALA, EPA and DHA. Alpha-linolenic acid (ALA) is found mainly in the oil of flaxseeds, hemp seeds, walnuts, rapeseed (canola oil), and soybeans. ALA reduces blood clotting, and is good for the heart. The body converts some of the ALA into two other essential omega-3 fats called EPA and DHA. These two are also found to a small degree in seaweeds, and there are vegan DHA supplements available made from micro-algae. Low levels of DHA have been associated with depression. A tablespoon of ground flaxseeds or a teaspoon of flax oil per day will meet the needs of most people.
All other essential vitamins, minerals, fats and carbohydrates are widely found in the plant kingdom. These nutrients can be easily obtained by maintaining variety in a plant food diet.
See the Vegetarian Position Paper by the Dietitians of Canada and the American Dietetic Association, for more information on vegetarian and vegan nutrition. The paper covers all stages of the life cycle (including pregnancy, lactation, infancy, childhood, adolescence, and old age).
If you have difficulty adapting to a vegetarian diet it may be that your body needs a few months to adjust and detoxify. Try experimenting with a variety of foods and cooking methods. If you have concerns about a nutrient deficiency, you can always have your blood tested, but rest assured that a varied vegetarian diet lacks no nutrients and is proven to be a powerful health promoting choice. Bon appetit!
Reviewed by Anne-Marie Roy R.D. except for the iron section which was recently updated in Oct 2009.
Notes and links to more information
The Vegetarian Position Paper by the American Dietetic Association and Dietitians of Canada has more information on all these key nutrients, including recommended servings.
• The Protein Myth, PCRM (2003). Requirements and the problems with high-protein diets.
• See page 3 of the Vegetarian Position Paper mentioned above.
• Iron in the Vegan Diet, vrg.org (2003). Iron content of selected vegan foods, comparison table of iron sources, and sample menus.
• Detailed article on iron by Jack Norris, RD, VeganHealth.org.
Note: Phytate (or phytic acid) found in the hulls of legumes, seeds, nuts and grains is also an inhibitor of iron when eaten at the same time, but these foods also contain a lot of iron so the effect is offset. Phytic acid is also reduced by cooking, soaking, sprouting and also during the making of foods like miso, tempeh and yeasted bread that involve fermentation. Phytate also plays a powerful role in prevention of colon cancer and osteoporosis. See http://en.wikipedia.org/wiki/Phytic_acid
• See page 6 of the Vegetarian Position Paper mentioned above.
• Calcium in the Vegan Diet, vrg.org (2003)
• What Every Vegan Should Know about Vitamin B12, veganhealth.org
• Iodine Deficiency Is On the Rise (from E Magazine, 2001)
• See page 7 of the Vegetarian Position Paper mentioned above.
Information on vegetarian diets
Physicians Committee for Responsible Medicine (PCRM)
The PCRM provides excellent vegetarian health and nutrition information. Topics include: pregnancy, children, protein, B12, calcium, dairy, eggs, athletic nutrition, frequently asked questions, and more. A Spanish page is also available: La Comida Vegetariana: Poderosa para la Salud.
Long list of nutrition tips including:
- understanding soy foods
- losing weight: a healthy approach
- managing food allergies and intolerances
- how to handle pre-pregnancy concerns
- nutrition for infants and children
- athletes and nutrition
Meal Planner and Shopping Lists: Get menu ideas to plan meals for the whole week, and print out a shopping list of all the ingredients you’ll need. Start by creating a free account.
Find out more about various diseases and conditions and how nutrition can play an important role in prevention and treatment.
Vegetarian nutrition & Health conditions affected by diet
The Analyst Online Health Service
This site has a nice summary of vegetarian/vegan nutrition concerns, and a long list of health conditions (from asthma to varicose veins) that are known to be improved by a vegetarian or vegan diet. A brief explanation of the dietary link is included for each condition, along with footnoted sources. This Naturopathic website also offers online analysis.