I have a friend who lives on salads, pasta and lots of coffee. A single mom, she strives to be the epitome of health in spite of her hectic city life: full-time job, volunteer work, teenage daughter. She does meatless on Mondays and holds the mayo and she eats a colorful diet. And to cover her bases, at just about every meal, she pops a slew of vitamin pills.

Research shows, when it comes to taking vitamins, it’s possible she has too much of a good thing.    
Without question, we need all 13 vitamins to help our bodies function properly. For instance, C supports healing and absorbs iron to fight fatigue; D helps process calcium for strong teeth and bones, sharpens the mind and boosts the mood; E elevates energy and helps other antioxidants fight off cancer-causing free-radicals; the Bs help convert food into energy. We get vitamins mostly from the foods we eat, and, when our diets are lacking, from pills, or supplemental vitamins.

And that’s where we can run into trouble. Some of us take double or triple the recommended dietary allowance of some vitamins, thinking, like my friend, that more is better. I’m guilty too: at 250 mg, I take more than three times the RDA of Vitamin C (it’s 60 mg for adults). And if I feel my body even thinking of catching a cold, for a few days I double or triple my daily dose. If 250 keeps me reasonably healthy, I presume, then 500 should do twice the job. But over time, that kind of thinking can misguided and unsafe. Studies show a definitive link between excessive vitamin use and increased risks of illness, including cancer and heart disease.

While the Food and Drug Administration is charged with monitoring dietary supplements, it doesn’t approve products before they go to market. By law, it can’t force manufacturers to tell you how much of a vitamin is too much – the supplement industry defeated those efforts long ago – so manufacturers can sell you double and triple the daily recommended allowance without any proof that those doses are safe. Use this guide by the National Academy of Sciences to determine how much is too much.

Your body absorbs vitamins and minerals from fruits, veggies, grains and dairy much more readily than from a pill. So try to go straight to the source to meet your needs. When you need to supplement, read the labels and unless directed by your health care provider, take just enough to meet the recommended allowance.

Like I tell my girlfriend, be careful out there in the wild, wild west of dietary supplements: pill-popping might not do what you think it’s doing; in fact, overdoing it may cause damage that no pill can undo.