Vitamins & Supplements Archive

News briefs

Vitamin D is an essential vitamin; low levels are associated with poor bone and muscle health and other chronic conditions, such as heart disease and cancer. Now, a study published online April 19, 2018, by PLOS One has tied higher vitamin D levels to a lower diabetes risk. Researchers followed 900 older adults (average age 74) for 12 years, checking their vitamin D and blood sugar levels during clinic visits. Compared with people whose blood levels of vitamin D were below 30 nanograms per milliliter (ng/ml), people with vitamin D levels of 30 ng/ml or more had one-third the risk for developing diabetes, and people whose D levels were 50 ng/ml or more had one-fifth the risk. This study does not prove that taking vitamin D supplements to raise blood levels of vitamin D would reduce the risk of diabetes, although that is possible. The Institute of Medicine maintains that a blood level of 20 ng/ml or higher is sufficient for 97% of the population. Other authorities think that levels higher than 20 ng/ml are better for health. Large studies are under way to help resolve these differences of opinion.

Image: © cegli | GettyImages

In the journals

Having a low blood level of vitamin D may be linked to a higher risk of developing some cancers, suggests a study published online March 7, 2018, by The BMJ. However, taking extra vitamin D to raise already normal levels does not appear to offer more protection.

Vitamin D is made by the skin from sunlight exposure and can also be obtained through fortified foods like cereal and milk, as well as from supplements. Researchers analyzed data from the Japan Public Health Center–based Prospective Study, involving 33,736 people ages 40 to 69. The people gave blood samples and were classed into four groups, ranging from the lowest to highest levels of vitamin D. They were then monitored for an average of 16 years, during which time 3,301 new cases of cancer were recorded among the participants.

You may need to stop taking blood thinners, certain painkillers, herbs, and supplements to reduce your risk for bleeding.

 Image: © Steve Debenport/Getty Images

No one wants to have surgery, even minor surgery, but sometimes minor procedures, such as a tooth extraction or a colonoscopy, are unavoidable. When that happens, you may hear that it's important to stop taking certain medications. Understanding exactly which drugs to suspend — and when — can be confusing. "I get a lot of questions about this," says Joanne Doyle Petrongolo, a pharmacist at Harvard-affiliated Massachusetts General Hospital.

Blood thinners

All surgery involves cutting body tissue, and that leads to bleeding. Blood thinners—medications like anticoagulants and antiplatelet drugs—can boost the risk for bleeding by keeping the blood from clotting.

Q: A friend recently recommended that I take the herb ginkgo biloba to protect against getting dementia. Is it effective, and is it safe?

A: The first thing you should consider is that the FDA doesn't regulate the manufacture of any herbal remedy, so the purity and potency of the ginkgo biloba you buy hasn't been checked.

Q: A friend recently recommended that I take the herb ginkgo biloba to protect against getting dementia. Is it effective, and is it safe?

A: The first thing you should consider is that the FDA doesn't regulate the manufacture of any herbal remedy, so the purity and potency of the ginkgo biloba you buy hasn't been checked.

In the journals

Taking a daily omega-3 fatty acid supplement might not reduce your chance of heart attacks or strokes if you already have heart disease or are at high risk for it, suggests a meta-analysis published online Jan. 31, 2018, by JAMA Cardiology.

The researchers compared 10 trials that included almost 78,000 people, approximately 47,000 of whom were men, with an average age of 64. Each trial involved at least 500 people who took daily doses of either an omega-3 fatty acid supplement or a placebo for at least a year. All participants had heart disease, had experienced a stroke, or were at high risk for these conditions.

On call

Q. I have read that vitamin K supplements can help prevent heart disease. Should I take them?

A. Vitamin K — which is found in high levels in green leafy vegetables like spinach, kale, and romaine lettuce — plays a role in helping the body make blood clotting proteins. Although some observational studies have suggested a heart benefit from diets high in vitamin K, studies of supplements have not shown a protective effect.

You need magnesium for many tasks. It's involved in more than 300 chemical reactions in the body. Muscles need this mineral to contract; nerves need it to send and receive messages. It keeps your heart beating steadily and your immune system strong. Most people can get enough magnesium by eating foods such as green leafy vegetables, whole grains, beans, nuts, and fish.

Dr. Bruce Bistrian, chief of clinical nutrition at Beth Israel Deaconess Medical Center and professor of medicine at Harvard Medical School, says magnesium deficiency in otherwise healthy individuals eating a balanced diet is rare. "The kidney has an extraordinary ability to reduce magnesium loss in urine, and thus achieve magnesium balance on a wide variety of intakes," he explains.

On call

 Image: © Svetl/Thinkstock

Q. How can I get my daily requirement for calcium if I am lactose intolerant?

A. We usually associate high-calcium foods with dairy products, like milk, cheese, and yogurt. If you cannot tolerate these foods from a digestive standpoint, you can still meet your calcium requirement by increasing your consumption of certain green leafy vegetables and calcium-fortified foods.

The net benefit of these popular supplements is very limited.

 Image: © stocksnapper/Thinkstock

Millions of Americans swallow an amber-colored capsule of fish oil each day, lured by its alleged health benefits. In the supplement aisle of most pharmacies, supermarkets, and big-box stores, the shelves are crowded with different brands of fish oil supplements (see "Fish oil: A brief history"). Many tout benefits for the heart. In fact, the label of one popular brand includes the phrase "May reduce coronary heart disease risk."

But those bold marketing claims haven't caught up with the latest science. Earlier this year, the American Heart Association (AHA) issued an updated advisory about fish oil supplements and their cardiovascular benefits. Their verdict: Fish oil supplements may slightly lower the risk of dying of heart failure or after a recent heart attack. But they do not prevent heart disease. (A separate AHA advisory about fish consumption is slated for release in 2018.)