Vetting your vitamins

Do you take a vitamin pill every day? If so, did you ever stop to consider whether you actually need it? Have you read the label? Do your doctors even know you're taking it?

Many nutrition professionals believe that vitamin and mineral supplements are generally unnecessary if you eat a balanced diet. Recent medical studies show that vitamins and minerals once thought to prevent or cure certain diseases don't. In fact, some can be harmful in large doses or when taken with certain medications.

Vitamins to watch for

What vitamins and minerals do seniors have issues with? We asked Katherine Zeratsky, a registered dietician nutritionist at the Mayo Clinic who writes about vitamins and nutrition at mayoclinic.com.

One vitamin that has a natural decline with age is B-12. "It takes a long time to develop a B12 deficiency, usually in the 70s or 80s," she says. Low vitamin B-12 levels are linked to memory loss and anemia.

"Often the deficiency gets missed, or mistaken for something else, but it is easy to test and treat with supplements," she adds.

Vitamin D deficiency is common in people who are homebound most of the time. That's because we need sunlight to produce it in our bodies.

"Most people can get enough by getting small amounts of sunlight, drinking fortified milk or eating certain fish," she says. "It allows you to absorb calcium, which is necessary for bone health."

The National Institutes of Health advises talking with your doctor about how much vitamin D you need, as taking too much may be harmful.

And speaking of calcium, the NIH recommends women over age 50 should consume 1,200 mg of the mineral daily. Men between the ages of 51 and 70 should consume 1,000 mg of calcium a day, and men over 70 should consume 1,200 mg per day. This can be done by eating calcium-rich foods such as dairy products and taking calcium supplements.

Research results

If you have read that certain vitamins might prevent disease, ask your doctor before buying them.

For example: Vitamin D supplements likely do not improve symptoms of knee osteoarthritis, according to results from a clinical trial published in the Journal of the American Medical Association.

Taking Vitamin E and selenium (a mineral) does not prevent prostate cancer. The Selenium and Vitamin E Cancer Prevention Trial found that the supplements, taken either alone or together, did not prevent prostate cancer, according to the NIH.

High doses of vitamin B-6 and folic acid were previously thought to prevent recurrence of a heart attack. But the Norwegian Vitamin Trial disproved that in 2005, saying they might be harmful instead.

Vitamin K, found in common vegetables such as greens, beets, spinach, lettuce, cabbage, cucumber, asparagus and more, can interact negatively with warfarin (brand name Coumadin), a blood thinner, the FDA warns. If you're taking warfarin, your doctor should have advised you about Vitamin K-rich foods to limit or avoid.

"Vitamins seem so benign. But whenever you start looking at medication anyone is taking, you need to look at their vitamins and their food together," Zeratsky says.

Other supplements

But buyer beware. Things like ginkgo biloba, a top selling plant-based supplement people take to prevent dementia and Alzheimer's disease, has no conclusive evidence that it does so, according to the National Toxicology Program (part of the Department of Health and Human Services), which studied it. In fact, the program recently found high doses of ginkgo biloba to cause cancer in lab mice.

Most people don't realize that, unlike drugs, vitamins and dietary supplements are untested by the FDA. Its website states, "The manufacturer of a dietary supplement or dietary ingredient is responsible for ensuring that the product is safe before it is marketed."

The best way to avoid problems with vitamins and other dietary supplements is to tell your primary care physician or pharmacist every vitamin and supplement you are taking, and what you are taking them with, Zeratsky says.

What if you go to your parents' house and see odd supplements they've suddenly purchased?

"You need to have a conversation about whether they know what's in it, and whether they know if it interacts with anything else they are taking," Zeratsky says. "It might be time to assess whether they're able to get to the store to buy and prepare healthy foods. Maybe it is getting harder for them to hold a knife and chop vegetables. Don't be afraid to take a look in their refrigerator."

Originally published in the Chicago Tribune Prime Time senior living section on September 10, 2013.