Return to story

Multivitamins boost health of some, but can harm others

June 17, 2007 12:35 am

MULTIVITAMIN- mineral supple- ments help some folks, but are dangerous for others.

Who needs 'em?

Scientists have shown multivitamin-mineral pills can help pregnant women, people who have had weight-loss surgery and those who have significant digestive problems such as Crohn's or celiac disease.

Older adults are at risk for vitamin B12 and vitamin D deficiency, as well as vision problems like macular degeneration, so a standard multivitamin-mineral is worthwhile for many of them.

Anyone who is losing weight should consider a multivitamin-mineral supplement--if you're not getting enough calories, you might not be getting enough vitamins and minerals, either.

Most folks who have osteoporosis need extra calcium and vitamin D. Athletes need extra B vitamins, according to research at Arizona State University. And vegetarians are at higher risk of deficiencies of vitamin B12, vitamin D, iron and zinc.

And everyone else?

Surveys show that 80 percent of health care workers and 35 percent of American overall take vitamins. That's despite a statement this year from the National Institutes of Health saying there isn't enough evidence yet to know whether supplements help prevent diseases for the average, healthy person.

In my opinion, supplements are optional for healthy folks.

Whatever your level of health, it's important to remember that while a multivitamin can provide low-cost "nutrition insurance," it's no substitute for eating a balanced diet and lots of fruits and vegetables.

Real foods contain thousands of naturally protective chemicals, which scientists are still discovering and naming. We can't fit all of these into a pill.

In some cases, supplements can be harmful.

Too much iron and vitamin A, especially, can be toxic. Too much vitamin K can interfere with blood-thinning medications such as Coumadin. High doses of beta-carotene alone can raise cancer risks in smokers.

Bottom line: Don't take more than 100 percent of the daily value for any vitamin or mineral--except vitamin D. More about that later.

And if you have liver or kidney disease, ask your doctor before taking supplements, even low-dose ones. Problems with the liver and kidney make needs for some vitamins increase, but also make it easier to overdose on others.

Most folks, unless they are pregnant or anemic, don't need supplemental iron. Often, vitamins marketed for senior citizens or men are iron-free. I myself buy these products, even though I am a woman in my early 30s.

If you're shopping for a multivitamin-mineral, check out the percentages on the back of label: Avoid megadoses, be cautious about iron, and make sure you're getting a useful form of chromium. Read on for details.

In my opinion, there's no convincing benefit to taking more than 100 percent of the daily value for any nutrients except vitamin D. Scientists are still debating, but it seems likely that they will raise the recommended intake of vitamin D.

Vitamin D inadequacy has been reported in 36 percent of healthy young adults and up to 57 percent of hospital patients in the United States, according to a report in the Mayo Clinic journal Proceedings last year.

Nursing-home residents who take 800 units of vitamin D have a 72 percent lower risk of falling. That's important, because falls can cause disabling injuries such as broken hips.

The current vitamin D goal is 200 to 400 units per day, depending on your age, but evidence shows it's safe for most adults to take 800 units a day.

Some scientists are recommending far more vitamin D, but I'm cautious for now.

If you have osteopenia or osteoporosis and need to protect your bones, you may need an extra supplement.

Most multivitamins don't have much calcium--it's hard to fit the whopping 1,000 milligrams most folks need into a single pill.

Look for a calcium-vitamin D pill that has 1,000 to 1,300 milligrams of calcium plus some vitamin D, and take it along with a regular multivitamin-mineral.

Or, eat three to four servings a day of calcium-rich foods such as dairy products, tofu or leafy vegetables.

More and more multivitamin-minerals contain chromium nowadays. It's still up for debate, but chromium may modestly help some people with diabetes, polycystic ovarian syndrome and a type of mild depression characterized by carbohydrate cravings.

The chromium picolinate form has been shown to be more effective than forms such as chromium chloride, so check the ingredient list on the bottle.

After all this talk about pills, I have to smile and say, "Don't forget to eat your vegetables!"

Jennifer Motl welcomes reader questions via her Web site, brighteating.com, or mailed to Nutrition, The Free Lance-Star, 616 Amelia St., Fredericksburg, Va. 22401.