Big studies give mixed news on fish oil, vitamin D

Although fish oil taken by healthy people, at a dose found in many supplements, showed no clear ability to lower heart or cancer risks, higher amounts of a purified, prescription fish oil, such as Vascepa, 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.

11 nov 2018--Taking fish oil or vitamin D? Big studies give long-awaited answers on who does and does not benefit 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. Same 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. Doctors cheered the results and said they could suggest a new treatment option for hundreds of thousands of patients like these.
Up to 10 percent of U.S. adults take fish oil . Even more take vitamin D , despite no major studies to support the many health claims made for it.
"Those who peddle it promote it as good for everything," but in this definitive test, vitamin D "showed a big nothing," said Dr. James Stein, a heart specialist at the University of Wisconsin-Madison. He had no role in the studies or ties to the companies involved.
Results were revealed Saturday at an 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 certain other fish. They reduce triglycerides and inflammation and may have other effects . There are different types, including EPA and DHA.
One study tested 4 grams a day of Amarin Corp.'s prescription Vascepa, which is concentrated EPA, in more than 8,000 patients with high triglycerides 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 percent 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 percent of the others.
That worked out to a 25 percent reduction in risk. Looked at individually, heart attacks, heart-related deaths and strokes all were lower with Vascepa. Only 21 people would need to take Vascepa for five years to prevent one of the main problems studied—favorable odds, Stein said.
Side effects may be a concern: More people on Vascepa were hospitalized for an irregular heartbeat—3 percent versus 2 percent of the comparison group. Doctors say that's puzzling because other research suggests fish oil lowers that risk.
The concern with the heart rhythm problem is that it can raise the risk of stroke, but there were fewer strokes among those on Vascepa, said study leader Dr. Deepak Bhatt of Brigham and Women's Hospital in Boston.
Vascepa costs around $280 a month; many insurers cover it. Amarin sponsored the study and some study leaders work or consult for the company.

A BROADER TEST

The other study tested a lower 1 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 that "a substantial benefit," but several independent experts disagreed because of the way the study was set up to track this and certain other results.
"These findings are speculative and would need to be confirmed in a separate trial," said the Cleveland Clinic's Dr. Steven Nissen.

FISHY COMPARISONS?

Both studies share a problem: the oils used for the comparison groups, which may not have been true placebos. The Vascepa study used mineral oil, which interferes with statin drugs, raises cholesterol, and might have made the comparison group fare worse and made Vascepa look better than it truly was.
The other study used olive oil, which might have helped that comparison group do better, possibly masking any benefit to the others from fish oil.
Leaders of both studies say any effect from the comparison oils isn't enough to alter the main results, and independent experts agreed. But Nissen, who is leading another fish oil study, is using corn oil as a comparison.

THE 'SUNSHINE' VITAMIN

Manson's study also tested vitamin D, which the skin makes from sun exposure. It's tough to get enough from foods like milk, eggs and oily fish, though many foods now are fortified with it. Some studies have found that people with lower levels of D are more likely to develop cancer, but it's not known if supplements alter that risk.
Study participants took 2,000 international units of D-3 (the most active form of vitamin D, also called cholecalciferol) 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.
"Cancer can take years to develop" so a difference may not show up right away, Manson said. "This looks promising" and people will be studied longer to see if the trend holds up, she said.
Several other experts said these numbers just hint at a possible benefit that needs more study.
"These 'positive' results need to be interpreted with caution," Dr. Clifford Rosen of Maine Medical Center Research Institute and Dr. John Keaney Jr. of the University of Massachusetts wrote in a commentary in the medical journal.

Red Blood Cell Omega-3 Levels Linked to Brain Volume

Levels of DHA in the lowest quartile tied to smaller brain volume, cognitive impairment

28 feb 2012-- In adults without clinical dementia, low red blood cell (RBC) levels of omega-3 fatty acids are associated with smaller brain volumes and lower scores on tests of visual memory and executive function, according to a study published in the Feb. 28 issue of Neurology.

Zaldy S. Tan, M.D., M.P.H., from the David Geffen School of Medicine at the University of California in Los Angeles, and colleagues investigated the association between RBC fatty acid levels in 1,575 dementia-free participants (aged 67 ± 9 years) and performance on cognitive tests and volumetric magnetic resonance imaging. In model A, adjustments were made for age, gender, and education; and in additional models, adjustments were also made for APOE ε4 and plasma homocysteine, for physical activity and body mass index, and for traditional vascular risk factors.

The researchers found that participants with RBC docosahexaenoic acid (DHA) in the lowest quartile had significantly lower total brain volume and greater white matter hyperintensity volumes, compared to those with RBC DHA levels in the second to fourth quartiles. The association with total brain volume persisted after multivariable adjustments. Participants with DHA and ω-3 index (RBC DHA + eicosapentaenoic acid [EPA]) levels in the lowest quartile had lower scores on tests of visual memory, executive function, and abstract thinking in all models, compared to those with levels in the second to fourth quartiles.

"Lower levels of RBC DHA and EPA in late middle-age were associated with markers of accelerated structural and cognitive aging," the authors write.

Several authors disclosed financial ties to the pharmaceutical and biotechnology industries.

Abstract

How much omega-3 fatty acid do we need to prevent cardiovascular disease?

New research in the FASEB Journal identifies the 'Goldilocks dose' of DHA that is 'just right' for preventing oxidative stress in men

03 sept 2009--A team of French scientists have found the dose of DHA (docosahexaenoic acid) that is "just right" for preventing cardiovascular disease in healthy men. In a research report appearing in the September 2009 print issue of The FASEB Journal (http://www.fasebj.org), the scientists show that a 200 mg dose of DHA per day is enough to affect biochemical markers that reliably predict cardiovascular problems, such as those related to aging, atherosclerosis, and diabetes. This study is the first to identify how much DHA is necessary to promote optimal heart health.

"This study shows that regularly consuming small amounts of DHA is likely to improve the health status of people, especially in regards to cardiovascular function," said Michel Lagarde, co-author of the study.

To determine the optimal dose of DHA, Lagarde and colleagues examined the effects of increasing doses of DHA on 12 healthy male volunteers between ages of 53 and 65. These men consumed doses of DHA at 200, 400, 800, and 1600 mg per day for two weeks for each dose amount, with DHA being the only omega-3 fatty acid in their diet. Blood and urine samples were collected before and after each dose and at eight weeks after DHA supplementation stopped. The researchers then examined these samples for biochemical markers indicating the effects of each dose on the volunteers.

"Now that we have a very good idea about how much DHA is just right, the next step is to try it out in an expanded clinical trial that involves many more people," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Until then, I'll stick with tasty foods that contain DHA, like fish, rather than getting a quick fatty-acid fix at the local vitamin store."

###

Receive monthly highlights from The FASEB Journal by e-mail. Sign up at http://www.faseb.org/fasebjournalreaders.htm. The FASEB Journal (http://www.fasebj.org) is published by the Federation of the American Societies for Experimental Biology (FASEB). The journal has been recognized by the Special Libraries Association as one of the top 100 most influential biomedical journals of the past century and is the most cited biology journal worldwide according to the Institute for Scientific Information. FASEB comprises 22 nonprofit societies with more than 80,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB advances biological science through collaborative advocacy for research policies that promote scientific progress and education and lead to improvements in human health.