A vegetarian diet can be very healthy – vegetarians have a lower than normal incidence of heart disease and cancer and lower risks of obesity and diabetes. But the vegan diet, in which you eat only plant based foods – no cheese, eggs, honey, or any other animal-derived foods – does require you to think about the nutrients you might be missing.
You can certainly get adequate amounts of protein from plant foods – whole grains, legumes, vegetables, seeds and nuts. Soy protein is equivalent to the protein you would get from meat, chicken, fish or eggs. Apart from that, the specific nutrients you should focus on include:
- Vitamin B12: Although this is found naturally only in foods from animal sources, you can get sufficient amounts from fortified breakfast cereals, fortified soy beverages and some types of brewer’s yeast. Still, I recommend taking a supplement of 50-100 micrograms of B12 in the form of a good multivitamin, sublingual tablet, nasal spray or gel.
- Iron: Good vegetable sources include cereals, grains, legumes, dates, prunes, raisins and greens. You can help your body absorb iron by taking 200-250 mg of vitamin C, preferably in divided doses when you consume these foods or by including foods high in vitamin C when you eat iron-rich foods. Do not take iron supplements unless prescribed by a physician.
- Zinc: The best plant sources are grains, nuts, legumes and spinach.
- Calcium: Good sources include sesame seeds, collards, kale, broccoli, sea vegetables and orange juice and soy milk fortified with calcium. Look for tofu fortified with calcium. Women need 1,000-1,200 mg of calcium per day from all sources; men need only 500-700 mg from all sources and do not need to take calcium supplements. Women who don’t get adequate dietary calcium should take 500-700 mg of calcium in supplement form in two divided doses with meals (take magnesium with calcium in a two to one ratio – that’s twice as much calcium as magnesium.)
- Essential fatty acids: By not eating fish, you’re missing out on natural sources of omega 3 fatty acids. Instead, make sure to include in your diet whole or unrefined grain products plus walnuts, freshly ground flaxseeds, or hemp seeds. Be aware that the vegetarian sources of omega-3s are not as good as oily fish. Consider taking a fish oil supplement or, at least, an algae-derived supplement of DHA.
- Vitamin D: As a vegan, you won’t get "D" from such dietary sources as fortified milk, eggs, salmon, tuna, mackerel and sardines. Some cereals are fortified with D, as are soy milk and fake meats, and our bodies make vitamin D with exposure to sunlight (still, most adults don’t get nearly enough). I recommend a daily supplement of 2,000 IU of vitamin D3 – cholecalciferol – for everyone (vegan or not).
Andrew Weil, M.D.