Taking fish oil or vitamin D? Big studies give a long-awaited answer to the question of who does and does not use these popular nutrients.
Oil from fish taken by healthy people, in a dose found in many supplements, did not show a clear ability to reduce the risk of heart disease or cancer. The same applies to vitamin D.
However, larger amounts of purified, prescription fish oil have reduced heart problems and heart deaths in people with high triglycerides, a type of fat in the blood, and other threats to heart disease. Doctors improved the results and said they could propose a new treatment option for hundreds of thousands of such patients.
Up to 10 percent of adults in the US take fish oil. Even more people take vitamin D, despite the lack of more serious research in support of many health claims.
"Those who grow it, promote it as good for everything," but in this final test, vitamin D "did not give anything away," said Dr. James Stein, a heart specialist at the University of Wisconsin-Madison. He did not study or connect with involved companies.
The results were revealed on Saturday at the American Heart Association conference in Chicago and published by the New England Journal of Medicine.
About fish oil
These oils, also called omega-3 fatty acids, are found in salmon, tuna and some other fish. They reduce triglycerides and inflammation and may have other effects. There are different types, including EPA and DHA.
In one study, 4 grams of the Amarin Corp recipe were tested. Vascepa, which is concentrated in EPA, has over 8,000 patients with high triglycerides and an increased risk of heart disease for a variety of reasons. Everyone has already taken statins, such as Lipitor or Zocor, to lower cholesterol. Half received Vasapa, and the rest – mineral oil capsules as a comparison.
After five years, about 17 percent of people in Vascepa have experienced one of these problems – heart attack, stroke, heart-related death or clogging of arteries requiring medical care – compared to 22 percent of others.
It reduced the risk by 25 percent. Individually, heart attacks, deaths and strokes associated with the heart were lower in Vasaca. Only 21 people will have to take Vasapa for five years to prevent one of the main problems that have been investigated, "said Stein.
Side effects can be a problem: more people on Vascepa were hospitalized due to irregular heartbeats – 3 percent compared to 2 percent of the comparator group. Doctors say this is puzzling because other studies suggest that fish oil reduces this risk.
The problem with heart rhythm is that it may increase the risk of stroke, but there were fewer strokes among Vasepas, said research leader Dr. Deepak Bhatt of Brigham and Women & # 39; s Hospital in Boston.
Vascepa costs around USD 280 per month; many insurers cover it. Amarin sponsored the study, and some leaders work or consult in the company.
In another study, a lower daily dose of 1 gram of another type of fish oil was tested – a combination of EPA / DHA sold as Lovaza or Omacor and in a generic form – with 26,000 people with no heart or cancer problems.
After about five years, indicators of the combined measure of heart attacks, strokes and other problems were similar for fish oil users and the comparator group. Cancer rates and deaths were also similar.
There were fewer myocardial infarctions in the fish oil group – 145 compared to 200 in the comparative group. The study director, Dr. JoAnn Manson of Brigham and Women & # 39; s, called it "a significant benefit," but several independent experts disagreed because of the way the study was conducted to track this and some other results.
"These findings are speculative and would have to be confirmed in a separate study," said Dr. Steven Nissen of the Cleveland Clinic.
Both studies have a common problem: oils used in comparison groups that may not have been a real placebo. Vasrap's study used mineral oil, which disrupts statins, raises cholesterol, and may worsen the comparative group and make Vascepa look better than it really is.
In the second study, olive oil was used that could help a better comparator group, possibly masking any benefit to others from fish oil.
The leaders of both studies say that any effect of comparative oils is not enough to change the main results, and independent experts agreed. But Nissen, who is running a fresh test of fish oil, uses corn oil as a comparison.
The Manson study also tested vitamin D, which the skin produces from exposure to the sun. It is difficult to get enough food, such as milk, eggs and fatty fish, although many foods are now fortified. Some studies have shown that people with lower levels of D are more likely to develop cancer, but it is not known whether supplements change this risk.
The study participants took 2,000 international units of D-3 (the most active form of vitamin D, also called cholecalciferol) or false vitamin tablets for five years.
Vitamin D had no effect on the likelihood of a heart attack, stroke or cancer development. After excluding the first two years of use, scientists observed fewer deaths due to cancer among people with vitamin – 112 compared to 149 in the placebo group.
"Cancer may take years to develop", so the difference may not appear immediately, Manson said. "It looks promising," and people will be tested longer to see if the trend continues, "she said.
Several other experts have stated that these numbers only point to a possible benefit that requires more research.
"These" positive "results should be interpreted with caution," Dr. Clifford Rosen from the Maine Medical Center Research Institute and Dr. John Keaney Jr. from the University of Massachusetts in a commentary in a medical journal.