13.7: What About Vitamin and Mineral Supplements?

Even if we don’t take vitamin and mineral supplements in pill form, virtually all of us in the United States eat foods that are fortified/supplemented with vitamins and minerals. As examples, milk is fortified with vitamin D; margarine is fortified with vitamin A and beta-carotene (a provitamin A); white flour—and the white bread, pasta, and pastries made from them—is enriched with iron and some B-vitamins; vitamin C is usually added to fruit-flavored sugar drinks; and even the most sugar-coated cereal typically adds a generous dose of vitamins.

Yet, as mentioned earlier, we’re confronted with a multitude of advertisements that would have us believe that we’re suffering from vitamin deficiencies of one kind or another. These ads are, of course, selling the very vitamins that they tell us we need. Indeed, most of us—even when doubting what the ads suggest—worry that we possibly might be deficient. And when in doubt, the general response is to take vitamins “just to be sure.”

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Vitamin Supplement “Rules of Thumb”

• Take single-vitamin supplements only when prescribed.
• Multivitamins should contain no more than 100% the Daily Value (100%DV).
• “Organic” vitamins have no advantage

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Let’s look again at one popular refrain—that tobacco-smoking creates unusually high needs for vitamin C. In principle, this is true. This is made much of by some pharmaceutical firms. For example, there’s a supplement called Stresstabs 600. The name apparently derives from the fact that the product has 600 mg of vitamin C—five times the amount recommended for smokers.

Smoking is one of the “stresses” envisioned to create extreme vitamin requirements—and thus to justify buying quantities of a vitamin for which true nutritional deficiencies are virtually unknown in America.

But even if one looks at the supporting data issued by makers of such vitamin tablets, one finds only what was mentioned earlier—that smoking can push C recommendations up by about 35 mg—an extra amount easily covered by a normal diet. The advertisers’ proposition thus appears to have little scientific substance.

What about those who, for example, “swear by large doses of vitamin C” in preventing their colds? Not to be forgotten is the placebo effect— the power of believing. In one study, for example, it was found that the subjects given either vitamin C or placebo capsules had tried to guess what was in their capsules. There was no difference in the number of colds between the vitamin C and control groups, but those in the placebo group who thought they were taking vitamin C had fewer colds than those in the vitamin C group who thought they were taking a placebo.

We’ve already discussed the perils of self-prescribing and treating oneself with large doses of vitamins. But what about smaller doses?

There are, in fact, situations where supplements at RDA levels are recommended. When one is on a very low calorie diet, for example, it can be hard to meet one’s nutritional requirements from the food itself, so a multivitamin pill makes sense. Also, as will be discussed in the next chapter, vitamin pills or fortified foods are recommended for certain people, e.g., vitamin B₁₂ for older adults, and folic acid for women of child-bearing age.