天博体育

Ask the doctor

Q. I've been taking vitamin D supplements for several years because my doctor said they might help me live longer. Am I wasting my money, or even causing myself harm?

A. You're right to be skeptical. Vitamin supplements of all types repeatedly have been tested for theoretical health benefits, and often the studies have shown none. There's no doubt that vitamin D supplements can help prevent or treat osteoporosis. Theoretically, they might reduce the risk of various diseases. What about the question you asked: whether vitamin D supplements help you live longer?

It's not clear that supplements are effective, but some evidence is encouraging.

Some people are wary of taking antidepressants to treat their mild or moderate depression. They may not want to deal with the hassle of prescriptions, the costs, the potential side effects (such as sexual dysfunction), or the worry that medication treatment could mean an endless commitment.

A study shows that, for many people, less is more when it comes to vitamin D.

There's no question that vitamin D can help build strong bones. But there may be a sweet spot when it comes to how much.

A study published in the Aug. 27 issue of JAMA found that, compared with people who took moderate amounts of vitamin D, adults who took large amounts daily not only didn't see additional gains in bone density, but in some cases ended up worse off.

Research we're watching

While eating more foods rich in omega-3 fatty acids may lower the risk of heart attack, that doesn't seem to reduce the risk of developing diabetes, according to a study published Aug. 24 in The BMJ. Prompted by past findings that this type of healthy fat might reduce diabetes risk and improve blood sugar (glucose) control, researchers decided to look further into the issue. They reviewed 83 randomized trials involving more than 120,000 people, both with and without diabetes. Each trial went on for six months or longer. These trials looked at whether increasing consumption of omega-3 fats (derived from fish or plants), omega-6 fats (such as those in soybean or corn oil), or total polyunsaturated fats could help lower blood glucose or reduce the risk of developing diabetes. They found that increasing the amount of omega-3, omega-6, or total polyunsaturated fats in the diet over an average study period of nearly three years didn't seem to have any effect on glucose metabolism or diabetes risk. It didn't matter whether the additional healthy fats came from supplements, enriched foods, or foods that were naturally rich in these fats.

Image: outline205/Getty Images

Research we're watching

Yet another study has found that most vitamin, mineral, and other nutritional supplements provide no protection against heart disease.

The new analysis, published July 8 in Annals of Internal Medicine, reviewed data from hundreds of clinical trials that pitted 16 different vitamins or other supplements against placebos. Most of them 鈥� including vitamin A, vitamin B₆, vitamin D, multivitamins, calcium, iron, and selenium 鈥� showed no association with a higher or lower risk of heart disease or death.

On call

Q. Are there any particular reasons why men should get a routine blood test to check for a vitamin D deficiency?

A. The importance of sufficient vitamin D for bone health has a long history. In the past few decades, several studies have suggested that vitamin D might have other health benefits as well.

Research we're watching

Do you know someone who is taking supplements in hopes of boosting their energy levels, gaining muscle, or losing weight? You may want to warn them about potential dangers. A study published online June 5, 2019, by the Journal of Adolescent Health found that products sold to boost energy, promote weight loss, or build muscle were linked to three times the number of severe medical events compared with vitamins. Researchers came to this conclusion after looking for supplement-related adverse events reported between January 2004 and April 2015 to the FDA. In total, they identified 977 cases of harm linked to supplements. Of those, 40% were severe medical events that resulted in death or hospitalization. While energy, weight loss, and muscle-building supplements appeared to be the riskiest, products sold to promote sexual function or to cleanse the colon were problematic as well. The FDA has found that some of these supplements contain dangerous substances or contaminants, such as pesticides, harmful chemicals, or heavy metals. Past studies have connected weight-loss and muscle-building supplements with serious, sometimes fatal, health problems, including liver damage, stroke, and testicular cancer.

Image: ronstik | Getty Images

News briefs

Vitamins and supplements won't help stave off dementia, but a healthy lifestyle might, suggest new guidelines released May 19, 2019, by the World Health Organization (WHO). The WHO warns that the number of new dementia cases around the world 鈥� currently 10 million per year 鈥� is set to triple by 2050. While there's no cure for any kind of dementia (such as Alzheimer's disease and vascular dementia), the WHO says it may be possible to delay the onset of the disease or slow its progression. The key: managing modifiable risks, such as chronic disease and unhealthy habits. The guidelines recommend that you keep your weight, cholesterol, blood pressure, and blood sugar under control; get lots of exercise; and eat a Mediterranean-style diet (which emphasizes olive oil, fruits, vegetables, nuts, and fish; minimizes red meats and processed meats; and includes a moderate amount of cheese and wine). The WHO also advises that you don't smoke and you avoid harmful use of alcohol (no more than one drink per day for women, no more than two drinks for men). But don't count on supplements to help you stave off dementia. The WHO says there's no evidence that vitamin B, vitamin E, multivitamins, or fish oil supplements help reduce the risk for dementia. The agency recommends against using supplements as a means to ward off cognitive decline.

Image: 漏 kali9/Getty Images

It's usually best to get calcium, magnesium, and potassium from food. Are you getting enough?

A healthy, balanced diet plays a major role in blood pressure control. And you should consume some specific minerals on a regular basis for good blood pressure management: calcium, magnesium, and potassium. But do most of us get enough of these? "If you're eating a healthy diet, you probably have nothing to worry about. But people eating a diet of processed and canned foods or taking certain medications might not be getting enough of these micronutrients," says Dr. Randall Zusman, director of the Division of Hypertension at the Massachusetts General Hospital Heart Center.