Calcium and Other Supplements
Q. With all the talk about carbs, both good and bad, it's easy to forget that our diets supply vital minerals and vitamins. But what's the most reliable source -- foods or supplements?
A. It really depends on the nutrient. As you age, vitamin B12 from food is less well absorbed by the body, so supplementation makes sense. If you don't eat lots of fortified foods (like Total cereal), you should take a multivitamin to ensure that you get adequate folic acid. Vitamin D is also difficult to get from your diet alone. Newer studies suggest that the majority of Americans would benefit from vitamin D, and this will mainly need to come from supplements. The RDA for vitamin D of 400 IU is almost certainly too low; 800 or 1,000 IU would be better for those over 40, and it is possible that even more might be helpful. But for now, until further studies are done, I would not suggest taking more than 1,000 IU as a regular supplement.
Q. Of course, we need to take a daily calcium supplement, right?
A. Not necessarily. You do need some calcium, but the exact amount is not clear. The United Kingdom recently reviewed their RDAs for this mineral, and they came up with 700 mg per day for everybody over 19, which is very different from the US RDA, which goes up to 1,200 mg for women over 50.
As a rough estimate, an average healthy diet gives you about 300 mg of calcium. Add one serving of dairy, like a glass of milk, and you get about another 400 mg, for a daily total of 700 mg. That's probably most of the benefit there is to be gained from calcium.
Women should not feel obligated to drink milk if they don't like it. And if they're not taking in any dairy foods, it's reasonable for them to take a calcium supplement to add maybe 500 to 1,000 mg, which would have no downside.
Q. But doesn't calcium help to prevent bone fractures?
A. Reducing the rate of fractures is the main justification given for high dairy consumption or high calcium supplement intake. But the evidence to support this doesn't exist. And, in fact, all the large studies that have looked at this topic have shown no benefit in terms of fracture reduction. And there are possible adverse consequences of high dairy consumption that are not yet totally proven, but are worrisome. We have seen some evidence of elevated risks of ovarian cancer and prostate cancer in several studies now. This area is one of the most unsettled scientifically; we are actively engaged in researching this.
But for now, if you really want to lower your fracture risk, I recommend taking more vitamin D -- it's likely to do more than calcium, because it helps your body absorb and use calcium. A large percentage of the U.S. population is already short on it. In addition to supplements, regular exercise, both cardio and strength training, is also key to building and maintaining bone strength. We have really strong evidence there.
Q. The headlines on vitamin E have been both for and against supplements. Where do you stand?
A. Taking a vitamin E supplement is prudent, since it's very inexpensive and, from what we can see, safe. For most people in midlife, it is reasonable to take 400 IU a day. In terms of protection against heart disease and Alzheimer's, there is a very good possibility of benefit, but no clear evidence as yet. But there doesn't seem to be any harm to taking it, either.
Originally published in MORE magazine, October 2004.
