Vitamins & Supplements Archive

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Figuring out all the factors that can affect your vitamin D level is complicated. Your body makes vitamin D when sunlight hits the skin. You can also get the vitamin from food (mainly because it's been added; few foods are natural sources of vitamin D) or by taking a supplement.

The process by which the body makes vitamin D is complex. It starts when the skin absorbs rays in the invisible ultraviolet B (UVB) part of the light spectrum. The liver and the kidneys also participate to make a form of the vitamin that the body can use.

In the journals

Much research has shown that oxidative stress plays a key role in the development of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease. As a result, antioxidant supplements like vitamin E and selenium have been proposed to prevent dementia. Yet a new study on older men published online March 20, 2017, by JAMA Neurology found no evidence they can help.

The Prevention of Alzheimer's Disease by Vitamin E and Selenium clinical trial included 7,540 men, average age of 67. Over a five-year period, the men were randomly assigned to receive 400 international units of vitamin E each day, 200 micrograms of selenium, both supplements, or a placebo. The supplements were stopped and 3,786 of these men agreed to be followed for an additional six years. They were routinely screened for cognitive problems and encouraged to see their doctor if the results suggested any kind of cognitive impairment.

Research we're watching

Dietary supplements made from red yeast rice contain substances called monacolins, which are similar to the active ingredient in cholesterol-lowering statin drugs. And like statins, red yeast rice products may cause rare but serious side effects, such as muscle injury and liver damage, as noted in a study published online January 19, 2017, by the British Journal of Pharmacology.

The study, based on a review of 13 years of patient data by Italian researchers, notes that people who can't tolerate statins often take red yeast rice supplements. But there are no studies testing the safety of red yeast rice compared with statins. In the United States, the FDA considers red yeast rice products that contain more than trace amounts of monacolins to be unapproved new drugs and therefore illegal to sell. Yet dozens of these unregulated products remain on the market.

It’s unclear why, but it appears that people with psoriasis are more likely to also suffer from diabetes.

The nutrient appears to have modest prevention power.

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Vitamin C is often touted as a natural cold remedy. The nutrient is featured in supplements promising to boost the immune system. Nobel laureate Dr. Linus Pauling famously claimed that taking large doses of vitamin C helps thwart a cold. Is there something to these claims? "The data show that vitamin C is only marginally beneficial when it comes to the common cold," says Dr. Bruce Bistrian, chief of clinical nutrition at Harvard-affiliated Beth Israel Deaconess Medical Center.

About vitamin C

Our bodies don't make vitamin C, but we need it for immune function, bone structure, iron absorption, and healthy skin. We get vitamin C from our diet, usually in citrus fruits, strawberries, green vegetables, and tomatoes. The Recommended Dietary Allowance for men is 90 milligrams (mg) per day, and for women, it's 75 mg per day.

There's no good evidence that taking calcium supplements can harm your heart. Still, it's best to get this mineral from foods, not pills.

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For decades, doctors have encouraged people to consume plenty of calcium, a mineral best known for building strong bones. About 43% of people in the United States, including close to 70% of older women, take supplements that contain calcium. Concern about osteoporosis—the bone-weakening disease that leaves older adults prone to fracturing a hip, wrist, or other bone—has driven this trend.

Calcium also keeps your muscles, nerves, and blood vessels working well, and it's one of the key minerals involved in blood pressure control. With regard to heart disease, though, there's one potentially confusing aspect of the calcium story. A test researchers often use to look for early signs of heart disease is known as a coronary artery calcium (CAC) scan (see "Seeing calcium specks inside arteries"). There's no direct connection between the calcium you consume and the amount in your arteries. But in recent years, several studies have observed a link between the use of calcium supplements and a higher risk of cardiovascular disease.

 Scientific evidence doesn’t support taking cranberry extract to prevent urinary tract infections.

Herbal supplements are sometimes advertised to improve a man’s sex life by increasing blood flow to the penis, but many are not proven effective for treating ED and may cause serious side effects.