In a look at another commonly consumed supplement, vitamin D, researchers found no effect on heart disease but saw a link to a decline in cancer deaths over time.
The research was released Saturday at the American Heart Association’s 2018 Scientific Sessions in Chicago and published in the New England Journal of Medicine.
About 43 million people in the United States take statins to lower LDL, or “bad,” cholesterol, and the drugs are credited with reducing the risk of heart attacks and strokes. But heart disease remains the leading killer of Americans. In recent years, a long, steady decrease in heart disease deaths has slowed. So researchers are seeking other ways to combat cardiovascular disease beyond known protective factors such as changes in diet, exercise and smoking habits.
One of the studies unveiled Saturday, named by the acronym REDUCE-IT, determined that people with cardiovascular disease who were already taking statins stood less chance of serious heart issues when they were also given two grams of the drug Vascepa (icosapent ethyl) twice a day.
The drug is a purified version of a fish-oil component that targets triglycerides, another type of fat in the blood. Elevated triglycerides can harden or thicken arteries, potentially leading to strokes and heart attacks. People who took the drug were compared with those who were given a placebo. The study involved more than 8,000 people.
The drug is made by Amarin Corp., which sponsored the research. In September, Amarin announced that the study had met its primary goals.
Deepak L. Bhatt, executive director of interventional cardiovascular programs at Brigham and Women’s Hospital in Boston, who led the study, said the results could change the practice of cardiology in the same way that the introduction of statins did more than 30 years ago.
“Honestly, I’ve been doing clinical trials for a long time. And I’ve not been involved in a trial that has this much potential to improve the lives of perhaps tens of millions of people,” Bhatt said.
In 2007, a large study in Japan determined that the same component of fish oil used in the REDUCE-IT study showed promise in protecting against cardiovascular problems. But that research did not compare the substance against a placebo, and was complicated by the large amount of fish in the typical Japanese diet.
The other fish-oil study released Saturday, called VITAL, looked at the effect of a different formulation of Omega-3 fatty acids in a drug called Lovaza. Researchers followed nearly 26,000 people for a median of more than five years. The results suggested that people given the drug were 28 percent less likely to suffer heart attacks than those given a placebo, and 8 percent less likely to have a variety of cardiovascular events. The effect was even more pronounced among African Americans, but the lead researcher said the results need further study before they can be relied upon.
People who ate fewer than 1.5 servings of fish weekly saw a drop in the number of heart attacks suffered when they increased their consumption of Omega-3s by taking the drug. The study did not find a decline in strokes.
JoAnne Manson, chief of the division of preventive medicine at Brigham and Women’s Hospital, who led the study, said it “further supports . . . the benefits of Omega-3 in heart health.”
Manson called the results “promising signals” about fish-oil consumption, but said they are not conclusive enough to compel people to begin taking the drug or fish-oil supplements. The study also showed that the medication is safe enough that people already taking fish oil have no reason to stop, she said in an interview.
People in the study were given 840 milligrams of the key fatty acids in fish oil each day, less than is found in a typical serving of salmon.
“We would encourage starting with more fish in the diet and having at least two servings a week,” Manson said. “One advantage of doing it through the diet . . . is that fish can replace red meat, saturated fat and processed food.”
Lovaza is manufactured by GSK, but is available in generic form. The study was sponsored by the National Institutes of Health.
The VITAL study also looked at vitamin D, which is often recommended to improve bone health in older women and for overall health in other people. It found that the vitamin had no effect on heart attacks or strokes and did not affect the incidence of cancer.
But vitamin D consumption may have some role in reducing the number of deaths from cancer two or more years later, the research showed. Manson suggested that vitamin D may help prevent cancers from metastasizing or becoming more invasive. But she said that idea needs more research.
She said people already taking modest amounts vitamin D, especially on the advice of doctors, have no reason to stop. But she warned against taking huge doses of the vitamin, such as 5,000 or 10,000 international units a day, unless a clinician recommends it, because the safety of that practice is not known.