Vitamins and minerals are marketed to keep you healthy. But some may carry more risks than benefits, especially as we age.

Supplements are most useful when they’re used to replace dietary deficiencies,” says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser. “Therefore, most of us don’t need them. Such needless use can be harmful, especially if you also take prescription medications.”

In addition, the evidence supporting supplements is often flimsy or mixed, and because of lax regulation, you can’t always be sure what they contain. The following four supplements may be especially harmful to your health if you’re over 50. 

Folic Acid Supplements

Research has suggested, but not proved, that folic acid (vitamin B9) may help ward off Alzheimer’s disease, depression, and heart disease.

Still, a recent study published by the American Journal of Clinical Nutrition links excess folate (including folic acid) to burning, tingling, or numbness in the extremities of people with a common gene variant.

“The odds were sevenfold higher for those who consumed more than 800 mcg daily,” says co-author Ligi Paul, Ph.D., of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

In addition, taking as little as 300 mcg daily may mask a B12 deficiency, which is relatively common in older adults, says Orly Avitzur, M.D., Consumer Reports’ medical director. “Undiagnosed, that can lead to nerve damage, cognitive trouble, and even psychiatric problems,” she says.

Folic acid can also reduce the effectiveness of the seizure drug fosphenytoin (Cerebyx and generic) and the cancer drug methotrexate (Rheumatrex and generic).

Who might need it? Women who are pregnant or planning to get pregnant, to prevent birth defects.

Calcium Supplements

You might take calcium supplements to strengthen your bones, which can weaken with age. But regular use may increase the risk of kidney stones and possibly heart disease.

A study in the Journal of the American Heart Association in October found that people who took calcium supplements over a 10-year period were more likely to accumulate the artery plaque that can lead to heart attacks.

Supplemental calcium can also negatively interact with some heart and thyroid medications.

Who might need it? People who eat little or no calcium-rich food, such as dairy products and leafy vegetables.

Iron Supplements

Anemia­, or low blood levels of iron­­, is more common with age. But taking too much iron can mask symptoms of anemia, which can be caused by internal bleeding, and lead to a missed diagnosis.

Iron supplements can also inhibit the absorption of certain antibiotics and blood pressure-lowering drugs such as captopril (Capoten and generic).

And if you have hemochromatosis, a common genetic condition, iron pills can lead to an overload of the nutrient in vital organs, potentially causing diabetes symptoms, heart problems, and liver damage.

Who might need it? People with diagnosed iron-deficiency anemia.

Vitamin E Supplements

These supplements are said by some to help prevent cancer, dementia, and heart disease, but there’s little proof—and plenty of reason to avoid them.

Research has linked regular use to a 13 percent higher risk of heart failure in certain populations. A study published in JAMA in 2011 also found that taking 400 IU daily may boost the likelihood of prostate cancer by 17 percent. Vitamin E supplements may also make some chemotherapy drugs less effective.

Who might need it? Our experts don’t recommend it for anyone.

3 Supplements to Consider

Vitamin D—It might make sense if you’ve been diagnosed with osteoporosis, get little sunlight, or rarely consume D-rich foods such as fatty fish, eggs, and fortified milk.

AREDS2 (a blend of vitamins C and E, copper, lutein, zeaxanthin, and zinc)—It might make sense if you have age-related macular degeneration, a leading cause of vision loss.

Vitamin B12—It might make sense if you’re a strict vegan, or if you regularly take certain kinds of heartburn drugs or metformin, a diabetes medication.