This week on The PediaBlog, we explored the role of vitamin and mineral supplements on our health. On Wednesday, we learned that giving male senior citizens vitamin supplements doesn’t improve their cognitive functioning (as they are often advertised to do); giving older people who have suffered a heart attack high doses of vitamin and mineral supplements doesn’t improve their their heart disease or prevent a recurrence; and, giving adults vitamin and mineral supplements doesn’t prevent heart disease or cancer. Then we read in an editorial and in the press that people are wasting money on these products.
On Thursday, we said “not so fast.” Pregnant women have higher metabolic demands and need folic acid supplements to prevent neural tube defects in their offspring. (In fact, all women of child-bearing age who may be considering getting pregnant should be taking a folic acid supplement before they conceive.) Growing children have age-related vitamin needs that may not be achieved with a “typical” (picky) kid diet. I would bet there are a lot of adults who also do not eat a healthy and balanced diet every day. When we don’t get the recommended amounts of vitamins and minerals in our diets, nutritional deficiencies develop and diseases follow. Back in our school-days we heard of rickets (vitamin D deficiency), scurvy (vitamin C), beriberi (vitamin B1), or pernicious anemia (vitamin B12). These deficiencies still exist in some corners of the world. But we in the developed world have learned to prevent these diseases by ensuring adequate quantities of vitamins in our food (and our supplements). Dr. James Hamblin has other concerns:
There is also the concern that deficiencies don’t just manifest as overt syndromes like scurvy, but sometimes as more insidious pathologies. They have been tied in limited research to cancers, high blood pressure, and atherosclerosis. (Likewise vitamin excess has been tied to many of the same things.)
Indeed, there are several well-know examples of the dangers of vitamin excess (hypervitaminosis). Beta-carotene and vitamin A supplements can cause the toxic symptoms of hypervitaminosis A. When excessive doses of vitamin D are taken, high blood levels of calcium result, causing kidney stones and hypertension. And a few years ago, a study found that men who took vitamin E supplements had a 17% increased risk of developing prostate cancer.
Pediatrician Paul Offit reviewed numerous studies which showed either no health benefits from vitamin and mineral supplements, or actual harm from them. Pointing to “the antioxidant paradox,” Offit asks:
Given that free radicals clearly damage cells — and given that people who eat diets rich in substances that neutralize free radicals are healthier — why did studies of supplemental antioxidants show they were harmful? The most likely explanation is that free radicals aren’t as evil as advertised. Although it’s clear that free radicals can damage DNA and disrupt cell membranes, that’s not always a bad thing. People need free radicals to kill bacteria and eliminate new cancer cells. But when people take large doses of antioxidants, the balance between free radical production and destruction might tip too much in one direction, causing an unnatural state in which the immune system is less able to kill harmful invaders. Researchers have called this “the antioxidant paradox.” Whatever the reason, the data are clear: high doses of vitamins and supplements increase the risk of heart disease and cancer; for this reason, not a single national or international organization responsible for the public’s health recommends them.
So what about a daily multivitamin alone? How harmful can that be? The Centrum daily multivitamin I’ve been taking gives no more than 100% of the daily requirement of each vitamin and mineral listed on the label. None of the vitamins and minerals are dosed in excess of 100%. (The “mega” vitamin I just bought at GNC has many times the required amounts of several vitamins and minerals — I think I’ll return them!)
Your pediatrician will continue to monitor your child’s dietary intake in the context of their age-specific nutritional needs. We’ll follow the points on their growth curves to reassure us (and you) of adequate growth. We understand than no supplement of a vitamin or mineral is an ideal replacement for the real thing found in real food. But we also acknowledge that kids will be kids — imperfect eaters — and that some vitamins (like vitamin D) and minerals (like calcium or iron) may need to be supplemented.
It’s an important conversation to have in the office at your child’s next well-visit. I hope these last three PediaBlog posts provide fuel for that discussion.