Studies yield mixed views on fish oil and vitamin D
CHICAGO: Taking fish oil or vitamin D? Big studies give long-awaited answers on who benefits from these popular nutrients.
Fish oil taken by healthy people, at a dose found in many supplements, showed no clear ability to lower heart or cancer risks. The same goes for vitamin D.
But higher amounts of a purified, prescription fish oil slashed heart problems and heart-related deaths among people with high triglycerides, a type of fat in the blood, and other risks for heart disease.
Up to 10% of US adults take fish oil. Even more take vitamin D, despite no major studies to support the many health claims made for it.
Results were revealed on Saturday at an American Heart Association conference in Chicago and published by the New England Journal of Medicine.
These oils, also called omega-3 fatty acids, are found in salmon, tuna and certain other fish. They reduce triglycerides and inflammation and may have other effects. There are different types such as EPA and DHA.
One study tested 4g a day of Amarin Corp’s prescription Vascepa, which is concentrated EPA, in over 8,000 patients with high triglycer- ides and a greater risk of heart problems for various reasons.
All were already taking a statin such as Lipitor or Zocor to lower cholesterol. Half were given Vascepa and the rest, mineral oil capsules as a comparison.
After five years, about 17% of those on Vascepa had suffered one of these problems – a heart attack, stroke, heart-related death or clogged arteries requiring medical care – versus 22% of the others.
That worked out to a 25% reduction in risk. Looked at individually, heart attacks, heart-related deaths and strokes were lower with Vascepa.
The other study tested a lower one gram daily dose of a different type of fish oil – an EPA/DHA combo sold as Lovaza or Omacor and in generic form – in 26,000 people with no prior heart problems or cancer.
After about five years, rates of a combined measure of heart attacks, strokes and other problems were similar for fish oil users and a comparison group. Cancer rates and deaths also were similar.
There were fewer heart attacks in the fish oil group – 145 versus 200 in the comparison group.
The study leader, Dr JoAnn Manson at Brigham and Women’s, called it “a substantial benefit”, but several independent experts disagreed due to the way the study was set up to track this and certain other results.
Manson’s study also tested vitamin D, which the skin makes from sun exposure. Participants took 2,000 international units of D-3 (the most active form of vitamin D) or fake vitamin pills for five years.
Vitamin D did not affect the odds of having a heart attack or stroke or developing cancer. After excluding the first two years of use, researchers saw fewer cancer deaths among those on the vitamin – 112 versus 149 in the placebo group.