Taking fish oil or vitamin D? The large study provides the long-awaited answer of who did and did not benefit from this popular nutrient.
Fish oil taken by healthy people, with doses found in many supplements, does not show a clear ability to reduce the risk of heart disease or cancer. Same with vitamin D.
But a higher amount of purified fish oil, a recipe for reducing heart problems and heart-related deaths among people with high triglycerides, a type of fat in the blood, and other risks for heart disease. Doctors encouraged the results and said they could suggest new treatment options for hundreds of thousands of patients like this.
Up to 10 percent of US adults take fish oil. Even more vitamin D is consumed, although there is no large study to support the many health claims made for it.
"Those who sell it promote it as good for all," but in this definitive test, vitamin D "shows nothing," Dr. James Stein, heart specialist at the University of Wisconsin-Madison. He does not have a role in studies or ties with the companies involved.
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
This oil, also called omega-3 fatty acids, is found in salmon, tuna, and certain other fish. They reduce triglycerides and inflammation and may have other effects. There are various types, including EPA and DHA.
One study tested 4 grams a day Amarin Corp Vascepa recipe, which concentrated EPA, in more than 8,000 patients with high triglycerides and a greater risk of heart problems for various reasons. All have taken statins like Lipitor or Zocor to lower cholesterol. Half were given Vascepa and the rest, mineral oil capsules as a comparison.
After five years, about 17 percent of those in Vascepa have suffered from one of these problems – heart attacks, strokes, heart-related deaths or blocked arteries that need medical care – compared to 22 percent.
It managed to reduce 25 percent of the risk. Looking individually, heart attacks, heart-related deaths and strokes are all lower with Vascepa. Only 21 people need to take Vascepa for five years to prevent one of the main problems studied – opportunities that are beneficial, Stein said.
Side effects may be of concern: More people in Vascepa are hospitalized for irregular heartbeat – 3 percent versus 2 percent of the comparison group. Doctors say it's confusing because other studies show fish oil reduces that risk.
The concern with the heart rhythm problem is that it can increase the risk of stroke, but there are fewer strokes between them in Vascepa, said study leader Dr. Deepak Bhatt from Brigham and Women 's Hospital in Boston.
Vascepa costs around $ 280 per month; many insurance companies cover it. Amarin sponsored the research and several study leaders worked or consulted for the company.
Another study tested a daily dose lower than 1 gram of different types of fish oil – a combo EPA / DHA sold as Lovaza or Omacor and in generic form – in 26,000 people without previous heart problems or cancer.
After about five years, the combined rates of heart attack, stroke and other problems are similar for fish oil users and comparison groups. Cancer rates and deaths are also similar.
There were fewer heart attacks in the fish oil group – 145 versus 200 in the comparison group. Study leader, Dr. JoAnn Manson at Brigham and Women 's mention that "the benefits are great," but some independent experts disagree because the way the research was done was to track this and certain other results.
"These findings are speculative and need to be confirmed in a separate experiment," Cleveland Doctor Dr Steven Nissen said.
Comparison of fish?
Both studies shared a problem: the oil used for the comparison group, which might not really be a placebo. Vascepa's research uses mineral oil, which interferes with statin drugs, increases cholesterol, and may make the comparison of groups worse and makes Vascepa look better than it actually is.
Other studies using olive oil, which might have helped the comparison group do better, might mask any benefits for others from fish oil.
The leaders of the two studies said that any effect of comparative oil was not enough to change the main results, and independent experts agreed. But Nissen, who is leading the study of other fish oils, uses corn oil as a comparison.
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Manson's research also tested vitamin D, which is made by the skin from sun exposure. It is difficult to get enough from foods like milk, eggs and oily fish, although many foods are now enriched with it. Some studies have found that people with lower levels of D are more likely to develop cancer, but it is not known whether supplements change that risk.
Study participants took 2,000 international D-3 units (the most active form of vitamin D, also called cholecalciferol) or fake vitamin pills for five years.
Vitamin D does not affect the possibility of having a heart attack or stroke or cancer. After excluding the use of the first two years, researchers saw fewer cancer deaths among those who took vitamin-112 compared to 149 in the placebo group.
"Cancer can take years to develop," Manson said. "This looks promising" and people will be researched longer to see if the trend persists, he said.
Some other experts say these figures only hint at the possibility of benefits that need to be studied further.
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