The latest recommendations from the Institute of Medicine have many people asking if they should toss out their bottles of calcium and vitamin D supplements. The answer to that question is probably a little bit different for vegans.
The IOM’s report was surprising in that they recommended an intake of vitamin D that was considerably less than what was expected and suggested that calcium supplements were not needed by most Americans and could even be dangerous.
For calcium, the committee left the RDA at its previous levels for almost all age groups, dropping intake recommendations only for older men. But they noted that calcium intake from food alone for almost all age and gender groups was adequate and that some people—especially older women—could be jeopardizing their health by piling on high doses of supplemental calcium in addition to consuming calcium-rich foods. Because the committee established a fairly small range of safety—the RDA for adults is 1,000-1200 mg and the upper limit for safe intake is 2,000 to 3,000 mg—some women were at risk for exceeding that upper limit.
This is not to say that supplements are in and of themselves dangerous; they are just unnecessary and potentially harmful for people who are already meeting their calcium needs from food. Since many vegans don’t meet calcium recommendations, though, this caution doesn’t necessarily apply to us.
The best advice is to aim for 1,000 milligrams of calcium per day, (or 1200 if you’re a woman over the age of 50) getting as much as you can from foods, and making up the difference with a supplement. I try to keep my calcium intake from foods high enough so that a daily supplement of 300 mg will put me in the range of 90 to 110 percent of the RDA. (I get almost all of mine from calcium-set firm tofu, fortified orange juice, and leafy greens, plus that little bit that is available from beans) As I’ve written about before, there is no reason to think that vegans have lower calcium needs than others.
Vitamin D is far more controversial. Much of the interest in high doses of this vitamin have been in response to its alleged relationship to cancer risk, muscle strength (and reduced risk for falling), the immune system, depression, heart disease and more. The RDA committee found all of the data to be too conflicting to make any conclusions; as a result, the vitamin D RDA is based strictly on its relationship to bone health.
The other issue has to do with defining vitamin D deficiency. This is assessed by looking at how much vitamin D is required to maintain optimal blood levels of the compound 25-hydroxy vitamin D (25OHD). The committee determined that practically all people are in good vitamin D status when their levels are at least 50 nmol/L. But other experts say that the optimal blood level of 25OHD is 75 nmol/L. Since there is no scientific consensus about this, it will continue to be a subject of some debate.
The current recommendation for vitamin D is 600 IUs per day (which is actually a very big increase over the previous RDAs). Vegans get their vitamin D the same way that omnivores do—from fortified foods and sunshine. The evidence suggests that vitamin D2 is as effective as D3 in raising blood levels of 25OHD, so there is no particular issue here regarding vegan nutrition. I take 1,000 IUs of vitamin D2 daily—which is still well below the upper limit for safety of 4,000 IUs—and I think I’m going to continue doing so until I’ve read the whole vitamin D report and learned more about what the vitamin D experts have to say in response to it.
One thing to keep in mind is that the recommendations assume that all of your vitamin D is coming from dietary sources. Those who make plenty of vitamin D from sun exposure have much lower dietary needs.