Research has not given a definitive answer as to whether fish oil and vitamin D supplements have health benefits, but…
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Almost 19 million Americans take fish oil supplements and about 37 percent of us take vitamin D. Many can be motivated by research that has suggested that these pills can protect heart health and prevent cancer. On Saturday, NPR published a story of long-awaited studies on both food supplements that called these claims questioned.
The result of the experiment, called VITAL, was complex. When researchers looked at cancer and overall cardiovascular events, they found no protective benefit from taking vitamin D or fish oil supplements. But when they only looked at myocardial infarction they found an advantage, especially for African Americans and people who eat some fish. (Researchers say additional studies are needed to see if these benefits persist.)
The story got a wave of questions from our readers and listeners. Many of you wrote in question, essentially should I stop taking these supplements?
To answer some of your questions, we spoke with Doctor JoAnn Manson, Head of the Preventative Medicine Department, the Medicine Department at Brigham and Women’s Hospital, which led the VITAL attempt. We also turned to Dr. Bess Dawson-Hughes, Senior Researcher and Head of the Bone Metabolism Laboratory at Tufts University School of Medicine.
The results of the VITAL study doubt the benefits of fish oil for cancer and cardiovascular disease. Should people just throw out their pills?
JoAnn Manson: No. For those who already apply, our results do not offer a clear reason to quit. If you want to consider starting, our recommendation is to talk to your healthcare provider, but it does not need to be done urgently. We are careful about taking very high doses, but at the level of fish oil [was taken] in our study there were no significant adverse effects. In addition, while fish oil does not reduce the risk of stroke or other cardiovascular problems, the risk of heart attack decreases by 28 percent and it is an important result.
Previous research suggests that fish oil can have greater benefits for heart health than for reducing stroke, as there are some mechanisms – like reducing irregular heart rhythm – which would be more important for heart attacks than stroke.
What about diet? Is it not a better way to get omega-3 fatty acids?
JoAnn Manson: We encourage people to eat fish and get these omega-3 in the diet. There may also be other benefits. For example, fish can replace red meat, saturated fat, processed foods and generally lead to a healthier diet. But some people do not like fish, will not eat fish, and so it may be a role to take the supplement.
In our study, it was more likely that those with low fish consumption would have access to fish oil. Those who already had two or more servings of fish per week did not seem to have any clear advantage. But those who eat less than one and a half fish reserves per week saw 40 percent reduction in myocardial infarction compared with placebo.
What about vitamin D supplements? Is there any reason to take them?
Bess Dawson-Hughes: In the VITAL study, participants participated in the experiment with sufficient levels of vitamin D, measured in their blood. So the question was that if you have enough vitamin D, will you add more added value? And they have answered the question clearly that for cancer and cardiovascular disease, the answer is no. I would conclude that if you already have enough levels of vitamin D, supplements will not protect you against cardiovascular disease and cancer.
But you can not decide yes or no on vitamin D supplements based on these results, as they did not take into account the benefits of vitamin D with calcium for bone health.
Vitamin D has historically and traditionally been considered important for bone health. We know that insufficient levels of vitamin D are associated with problems such as less calcium absorption, less bone formation and, in extreme cases, more fractures.
Should people who do not get much sun exposure or people who have darker skin worry about their vitamin D levels?
Bess Dawson-Hughes: If you do not have enough D levels, make sure you get what the medical institute recommends, which is 600-800 international units per day [for adults, depending on age] . Most people can not get it in their diet because vitamin D is in very few foods like fat fish and egg yolks. And of course, in winter, you make very little vitamin D because it is less sunlight.
For people at high risk of vitamin D deficiency, it is recommended that they have vitamin D levels saturated and they take dietary supplements to get vitamin D levels up to what the guidelines recommend.
High-risk individuals include darker skin, which reduces the body’s ability to synthesize vitamin D from ultraviolet rays from the sun. Individuals who wear sunscreen consistently and carefully individuals wearing clothes that cover much of their body; very overweight people and those who rarely are out, for example, nursing homes. These people should have tested the levels of vitamin D to determine if they should take dietary supplements.
For someone with light skin in a temperate climate at dinner, 10 minutes direct exposure to the sun over 10 percent of your body – like your arms and face – will give you what you need to make adequate levels of vitamin D.