Vegan for Life: Everything You Need to Know to Be Healthy on a Plant-based Diet

by Jack Norris

as people age, no matter what type of diet they follow, their ability to absorb vitamin B12 found naturally in foods begins to decline.

For this reason, the National Academies recommends that all people over age fifty get at least half of the RDA for B12 from some combination of supplements and fortified foods. Many older people may not know this, but vegans who are paying attention to good nutrition advice are already using vitamin B12 supplements or fortified foods.

There is some evidence that methylcobalamin is less stable in supplements and it seems that it takes very high doses to maintain B12 levels.

And while there is a small amount of cyanide in cyanocobalamin supplements, the amount is inconsequential compared to what occurs naturally in the diet. A twice weekly supplement of 1,000 micrograms of cyanocobalamin would provide an average of 6 micrograms of cyanide per day which is well below the minimum risk level of 3,175 micrograms per day.18

First, it’s a good idea to choose supplements that are chewable (or in liquid form) to maximize vitamin B12 absorption.

Consume two servings per day of fortified foods providing 2 to 3.5 micrograms of vitamin B12 each. • Take a daily vitamin B12 supplement of at least 25 micrograms (25 to 100 micrograms is a good range). • Take a supplement of 1,000 micrograms of vitamin B12 two times a week.

“This touches on the issue of how vegans should handle the caveman argument. Many of us are tempted to strain credulity and torture the evidence to ‘prove’ humans are ‘naturally’ vegan. This is a trap, and one into which carnists (especially paleo-dieters) would love us to fall; the evidence isn’t on our side. There’s no doubt that hominids ate meat.… The argument for veganism has always been primarily ethical, and ought to remain that way. It’s based on a concern for the future, not an obsession about the past.”

“Further, if the motivation for your diet is moral and/or spiritual, then you will want the basis of your diet to be honest as well as compassionate. In that case, ditching the false myths of naturalness presents no problems; indeed, ditching false myths means that you are ditching a burden.”

Fat is also essential for the absorption of vitamins D, E, and K as well as beta-carotene, the plant compound that is converted to vitamin A. Very low fat diets can result in poor absorption of these nutrients and also of a number of health-promoting phytochemicals.

According to the National Academies, the Acceptable Macronutrient Distribution Range for fat intake is between 20 and 35 percent of calories.

The acceptable range of fat intakes for toddlers (ages one to three years) is 30 to 40 percent of calories. For children ages four to eighteen, it is 25 to 35 percent.

Linoleic acid (LA) is an essential omega-6 fat and alpha-linolenic acid (ALA) is the essential omega-3 fat. Even vegan diets that are relatively low in fat almost always provide enough linoleic acid. Recommended amounts are 12 grams for women and 17 grams for men. Walnuts, seeds, soyfoods, and many vegetable oils are especially rich in linoleic acid. Vegans tend to have adequate intakes of this nutrient, often consuming more than nonvegetarians.3,4

Some vegans may not meet needs for the omega-3 essential fatty acid, ALA, however, since this fat is found in only a handful of plant foods. Recommended intakes of ALA for adults are 1.1 grams per day for women and 1.6 grams for men. Meeting those needs isn’t difficult, but it requires a little bit of attention to food choices.

These are EPA and DHA, which are the “long-chain” omega-3 fatty acids. These fats have been thought to be important for lowering risk for cardiovascular disease, and possibly also for protecting cognitive function and eye health.

While vegans don’t have direct sources of DHA and EPA in their diets, the body can synthesize them from the essential fatty acid ALA under the right conditions. Conversion of ALA to these long-chain fats varies considerably based on genetics and lifestyle factors, but on average, 5 percent of ALA is converted to EPA and 0.5 percent is converted to DHA.

Some evidence suggests that high intakes of the omega-6 fatty acid LA suppress conversion of ALA to DHA and EPA.

The World Health Organization and Food and Agriculture Organization recommend an LA intake between 2.5 and 9 percent of calories, saying that the higher end of the range reduces risk for heart disease.31 The National Academies also doesn’t recommend a specific ratio of LA to ALA, but rather recommends consuming diets that provide between 5 and 10 percent of calories from LA and 0.6 and 1.2 percent of calories from ALA. Vegan intakes of LA in recent studies have ranged from 5.1 to 9.3 percent of calories, putting them within the recommended range.

is easy enough to modify the ratio of these fats in your diet by limiting foods that are very high in LA such as safflower, sunflower, corn, and soybean oil, and getting more fat from nuts, avocado, olives, and olive and canola oils. But beyond those choices, we don’t recommend efforts to achieve a specific ratio.

Preliminary research suggests that a supplement providing 200 milligrams of DHA from microalgae per day for three months can raise blood DHA levels in vegans by as much as 50 percent.35 Other studies of vegetarians (not necessarily vegans) have also shown the positive effects of taking DHA supplements.

But because the research on the overall benefits of omega-3s is so conflicting, it’s hard to know whether these supplements are necessary for vegans. While we are not convinced that they are, we’re also not convinced that the lower blood levels of DHA and EPA in vegans is unimportant. Until we know more, supplementing with very small amounts, around 200 to 300 milligrams of DHA every two or three days is a reasonable approach for those vegans who wish to err on the side of caution.

Because ALA converts more efficiently to EPA than DHA, and because some DHA can convert back to EPA, it’s likely that taking supplements of DHA alone is enough provided you are meeting needs for ALA. There is some evidence, although again it’s conflicting, that omega-3 supplements could help wi...

Packed with saturated fat—it has more than either butter or lard—coconut oil has developed a surprising reputation as a health food.

The World Health Organization cautions against consuming a diet that is less than 15 percent fat for adults or less than 20 percent for premenopausal women.31 We recommend that vegans strive for a fat intake somewhere between 20 and 30 percent of calories. That means between 22 and 33 grams of fat for every 1,000 calories you consume.

Minerals like iron and zinc are absorbed less well from plant foods than from animal products. There are a number of reasons for this, but the most important is the presence of phytate in the diet.

Toasting nuts and seeds, and sprouting beans and grains, reduces the effects of phytate. So does soaking these foods and discarding the water before using them in a recipe. Foods that contain vitamin C are especially effective for increasing iron absorption.

Even among Americans who eat meat, iron deficiency is the most common nutrient deficiency. Poor iron status is seen most often in toddlers and premenopausal women and is especially common in pregnant women.1–3

Premenopausal women lose more iron than men because of menstrual losses. Their iron needs are more than twice what men require, which explains why iron deficiency is so much more common among younger women. With menopause, iron needs decrease. The recommended daily iron intake is 18 milligrams for premenopausal women and 8 milligrams for men and postmenopausal women.

Meat contains both types of iron, but plant foods contain only nonheme iron.

But the most effective way by far to release iron from phytate is to add vitamin C-rich foods to meals. Vitamin C changes the iron into a form that is more easily absorbed. The effects of vitamin C on iron absorption are rather dramatic.

iron and vitamin C must be consumed at the same time. The key to optimizing iron status for vegans is to include iron-rich and vitamin C–rich foods in the same meal.

You should know, however, that certain dietary factors like tannins in coffee and tea and high doses of calcium reduce absorption of nonheme iron. It’s important to take calcium supplements between meals, and if you are trying to maximize iron absorption, to avoid drinking coffee and tea with meals.

Vegans who consume vitamin C–rich foods with their meals and who avoid coffee, tea, and calcium supplements with meals are likely to need much less iron than the amount specified by the National Academies. Pairing iron-rich foods with vitamin C-rich foods isn’t at all difficult and chances are you already do it.

The adult RDA for zinc is 11 milligrams for men and 8 milligrams for women. But because absorption from plant foods is quite a bit lower than from animal foods, the National Academies suggests that zinc needs could be as much as 50 percent greater for vegans. That means that vegan zinc needs would be 16½ milligrams for men and 12 milligrams for women. Vegan intakes often fall somewhat below these recommendations.

As with iron, phytate is one of the important factors affecting zinc bioavailability, so many of the food preparation techniques that boost iron absorption also work for zinc. (Note, however, that vitamin C does not appear to enhance zinc absorption despite its very beneficial effects for iron.)

Good sources of iron are beans, leafy green vegetables, and dried fruit. Good sources of zinc are beans, nuts, peanuts, peanut butter, pumpkin seeds, sunflower seeds, bran flakes, wheat germ, and tempeh.

Include a good source of vitamin C at every meal to increase iron absorption. Among the best sources are oranges, broccoli, strawberries, grapefruit, leafy green vegetables, bell peppers, Brussels sprouts, and cauliflower.

Consume coffee and tea between meals rather t...

Take calcium supplements between meals rather ...

Naturally occurring compounds known as goitrogens, which are found in soybeans, flaxseeds, and raw cruciferous vegetables (broccoli, Brussels sprouts, cauliflower, and cabbage), counteract the activity of iodine. A diet high in goitrogens can cause hypothyroidism if the diet is too low in iodine. But as long as your diet is adequate in iodine, there is no reason to avoid soyfoods or other sources of goitrogens.

To put those numbers into perspective, the RDA for iodine is 150 micrograms and the National Academies has set 1,100 micrograms per day as the maximum amount per day that people can safely consume.

Like all minerals, iodine can be toxic at very high levels.

The recommended iodine intake for adults is 150 micrograms per day.

If you use added salt on your foods, choose iodized salt. One-quarter teaspoon provides 76 micrograms of iodine, which provides enough to ensure that you’re meeting needs since plant foods will provide at least some iodine. Different “natural” salt preparations, including sea salt, have variable amounts of iodine and aren’t dependable unless they are iodized. The salt added to processed and fast foods is rarely iodized. Nor is the salt used to make soy sauce, tamari, or miso.

If you prefer not to use salt, take a modest iodine supplement providing 75 to 150 micrograms of iodine three to four times per week.

Don’t overdo it with supplements, though, since the range of safe iodine intake is relatively small, and it’s important to avoid intakes above the upper limit for safety.

The RDA for vitamin A is 900 RAE for men and 700 RAE for women.

Where we once thought that vegan diets automatically provided enough vitamin A, it’s now clear that getting enough requires at least some diligence.

Just 1 cup of spinach or a ½ cup of carrot juice or a ¼ cup of sweet potatoes is enough to meet needs for the entire day.

The best sources of vitamin K are leafy green vegetables. Soy, canola, and olive oils are also good sources.

Finally, the National Academies has not established any specific recommendations for vitamin K2. We can say with assurance that vitamin K2 is not a separate nutrient, and vegans do not need it in their diet.