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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 Consumer Reports’ chief medical adviser, Marvin M. Lipman. “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 products may be especially harmful if you’re older than 50.

Folic acid

Folic acid (vitamin B9) has been suggested — but not proved — to help ward off Alzheimer’s disease, depression and heart disease. But 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 [micrograms] daily,” says co-author Ligi Paul 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 Consumer Reports’ medical director, Orly Avitzur. “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

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 than others 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

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

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 2011 study published in JAMA also found that taking 400 international units 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? Consumer Reports’ experts don’t recommend it for anyone.

And three to consider taking

Most of us get all of the vitamins and minerals we need from food. But you might want to ask your doctor about the following supplements:

●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.

Copyright 2017. Consumers Union of United States Inc.

For further guidance, go to ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.