Research has not provided a definitive answer on whether fish oil and vitamin D supplements have health benefits, but it is clear that eating fish is beneficial. Enn Li Photography / Getty Images Hide caption

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Enn Li Photography / Getty Images

Research has not provided a definitive answer on whether fish oil and vitamin D supplements have health benefits, but it is clear that eating fish is beneficial.

Enn Li Photography / Getty Images

Nearly 19 million Americans take fish oil supplements and 37 percent of us take vitamin D. Many may be motivated by research suggesting these pills may protect heart health and prevent cancer. On Saturday, NPR released a story of much-awaited research on both supplements that challenged these claims.

The results of the study called VITAL were complex. When studying cancer and cardiovascular events, researchers found no protective benefit from taking vitamin D or fish oil supplements. But if they just looked at heart attacks, they found an advantage, especially for African Americans and people who are low on fish. (Researchers say more study is needed to see if these benefits persist.)

The story sparked a wave of questions from our readers and listeners. Many of you have written and asked if I should stop taking these supplements.

Vitamin D and fish oil supplements tend to be disappointing in long-awaited research

To get answers to some of your questions, we spoke to Dr. JoAnn Manson, Head of Preventive Medicine, Brigham and Women’s Hospital Medical Department, who led the VITAL study. We also turned to Dr. Bess Dawson-Hughes, Senior Scientist and Director of the Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

The results of the VITAL study cast doubts on the benefits of fish oil in cancer and cardiovascular disease. Should people just throw their pills away?

JoAnn Manson: No. For those already taking supplements, our results do not offer a clear reason to stop. If you are considering getting started, we encourage you to speak to your doctor. However, this does not have to be urgent. We warn against taking very high doses, but at the level of fish oil [was taken] There were no significant side effects in our study. While fish oil didn’t reduce the risk of stroke or other cardiovascular problems, it did reduce the risk of heart attacks by 28 percent, and that’s a significant finding.

Previous research suggests that fish oil may have greater benefits for heart health than for reducing stroke because there are some mechanisms – such as reducing an irregular heartbeat – that would be more important for a heart attack than for a stroke.

What about diet? Isn’t that a better way to get omega-3s?

Manson: We encourage people to eat fish and include these omega-3 fatty acids in their diet. There may be other benefits as well. For example, fish can replace red meat, saturated fat, and processed foods and lead to a healthier diet in general. However, some people don’t like fish, don’t eat fish, and so there might be a role in taking the supplement.

In our study, those who had low fish consumption were more likely to benefit from fish oil supplements. Those who already had two or more servings of fish a week did not seem to have any clear benefit. With less than 1 1/2 fish servings per week, the heart attack could be reduced by 40 percent compared to placebo.

What about vitamin D supplements? Is there a reason to take it?

Bess Dawson-Hughes: In the VITAL study, the participants with sufficient vitamin D levels, measured in their blood, took part in the study. So the question was, do you have enough vitamin D to add more value? And they answered that question very clearly that the answer to cancer and cardiovascular disease is no. I would conclude that if you already have adequate vitamin D levels, adding more won’t protect you from cardiovascular disease and cancer.

However, based on these results, you cannot decide a yes or no to vitamin D supplements as they failed to take into account the benefits of vitamin D along with calcium for bone health.

Vitamin D has historically and traditionally been considered important for bone health. We know that inadequate vitamin D levels are linked to problems such as lower calcium intake, lower bone formation and, in extreme cases, more fractures.

Should people who don’t get a lot of sunlight or people with darker skin be concerned about their vitamin D levels?

Dawson-Hughes: If you don’t have adequate vitamin D levels, you need to make sure you are getting the Institute of Medicine’s recommendations, which is 600-800 international units per day [for adults, depending on age]. Most people cannot include this in their diet because very few foods such as fatty fish and egg yolks contain vitamin D. And of course you make very little vitamin D in winter because there is less sunlight.

For people at high risk of vitamin D deficiency, it is recommended that vitamin D levels be measured and supplements be taken to bring vitamin D levels up to the recommended levels in the guidelines.

Risk groups include people with darker skin, who reduce the body’s ability to synthesize vitamin D from the sun’s ultraviolet rays. People who wear sunscreen regularly and thoroughly; People who wear clothing that covers a large part of their body; very overweight people and those who are seldom outside, such as B. Residents of nursing homes. These people should have their vitamin D levels tested to see if they should be taking supplements.

In general, 10 minutes of direct sunlight over 10 percent of your body – such as your arms and face – for someone with fair skin in a temperate climate at noon will get what you need to achieve adequate vitamin D levels.

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