Following a vegan diet means avoiding the obvious animal-based foods – meat, poultry, dairy, eggs, and fish – but if you’re not careful, you could be avoiding some essential nutrients too. The reason? Plant-based foods that comprise a vegan diet supply less (or less bioavailable) vitamin B12, vitamin D, calcium, iron, and zinc than those found in a mixed diet.
- Vitamin B12: While Vitamin B12 isn’t of concern for vegetarians who consume dairy products or eggs, for strict vegans, fortified products like cereal, soy milk, or nutritional yeast (a great addition to fresh popped popcorn!) are essential in meeting your daily B12 needs.
- Vitamin D: Individuals who follow a vegan diet, religiously wear sunscreen, live north of 37° latitude (north of Denver, Washington D.C., and San Francisco), are over age 65, or have dark skin, should consider a vitamin D supplement. The vegetarian version, ergocalciferol (Vitamin D2), is derived from yeast or algae, and according to experts, taking 1000 IU of ergocalciferol is equally as effective as a similar dose of vitamin D3. For an extra dietary boost, sauté up some dried shiitake mushrooms (~130 IU vitamin D per cup, rehydrated) in your next stir-fry; dried shiitakes (but not fresh!) are among the few naturally-occurring sources of Vitamin D in food.
- Calcium: The recommended intake of calcium for adults (vegan and omnivore alike) is 1000mg per day, or the equivalent of 3 cups of fortified soymilk, calcium-fortified orange juice or chinese mustard greens (gai choy). To get an equivalent amount of bioavailable calcium as one serving of these foods, you can have 2-3 cups of chopped collards, kale or bok choy or a 5 oz serving of tofu that’s been set in calcium sulfate (most brands are). Other respectable vegan sources of calcium include dried figs, toasted unblanched almonds, sesame paste/tahini, white beans, edamame (boiled soybeans) and blackstrap molasses; eating small portions of several of these foods can add up over the course of a day. On days that you come up short, a supplement can make up the difference.
- Iron: Iron found in plant-based proteins is poorly absorbed, so vegans require more of it to achieve the same benefits. Vegetarian women need 32mg of iron daily; vegetarian men need 14mg per day. Vitamin C (e.g. adding fresh tomato salsa to a brown rice and bean burrito) can improve iron absorption from foods, and low dose iron supplementation can help bridge the gap without causing constipation or an upset stomach.
- Zinc: Generally, vegans have adequate zinc status, despite the fact that plant foods contain very little zinc, but it certainly can’t hurt to sprinkle zinc-rich wheat germ or pumpkin seeds on your morning cereal to meet the 9mg per day requirement for women and 11mg per day requirement for men.
Also, check out this article that addresses vegan options for adequate omega-3 essential fatty acids if you avoid fish.