New research shows that vitamin D supplements and fish oil may not be worth it

Taking fish oil supplements to prevent cardiovascular disease and cancer may not be effective.

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Cathy Scola / Getty Images

Taking fish oil supplements to prevent cardiovascular disease and cancer may not be effective.

Cathy Scola / Getty Images

Many people regularly take nutritional supplements such as vitamin D and fish oil in the hope of avoiding the leading causes of death, such as cancer and heart disease.

But the evidence on the possible benefits of the supplements has been mixed.

Long-awaited government-funded research has provided the clearest evidence to date of the utility of taking supplements. And the results – published in two articles – are disappointing.

"Both trials were negative," said Dr. Lawrence Fine, head of the clinical application and prevention branch of the National Heart, Lung and Blood Institute, a division of the National Institutes of Health, which funded the studies.

"Overall, they showed that neither fish oil nor vitamin D reduced the incidence of heart disease or cancer," Fine says.

The results were presented at the scientific sessions of the American Heart Association in Chicago and published online Saturday by the New England Journal of Medicine. One document focused on vitamin D supplementation and the other on fish oil.

The trials involved nearly 26,000 healthy adults aged 50 and over, with no history of cancer or heart disease, who participated in the VITAL research project. Twenty percent of the participants were African-Americans.

Some participants took either 1 gram of fish oil – which contains omega-3 fatty acids – plus 2,000 international units of vitamin D a day. Others have consumed the same dose of vitamin D and a placebo, while others have ingested the same dose of fish oil and a placebo. The last group took two placebos. After more than five years, the researchers found no overall benefit.

Although the overall results were disappointing, there seemed to be a beneficial effect on one of the aspects of heart disease and fish oil: heart attacks.

Taking fish oil has reduced the risk of heart attack by about 28%, which is a "statistically significant" finding, says Dr. JoAnn Manson, Chief of the Division of Preventive Medicine at Brigham Hospital and Women's Boston. She led the research.

Those who seemed to benefit the most were those who did not usually eat a lot of fish in their daily diet, as well as African-Americans, says Manson.

African-Americans participating in the study had a 77% lower risk of heart attack compared to placebo, which represents a "dramatic reduction," Manson said. Further research is needed to confirm these findings, she adds, but "in the meantime, it would be reasonable for African-Americans to discuss with their health care providers to find out if they could be candidates for the study." taking fish oil supplements ".

In an editorial also published in the New England Journal of Medicineauthors John F. Keaney and Clifford J. Rosen challenge some of the analyzes in the study and write that positive results for heart attack and African-Americans and people who consume little fish should be taken into account. interpreted with caution.

No serious side effects, such as bleeding, high blood calcium or gastrointestinal symptoms, have been found with either supplement.

Manson and his colleagues plan to further analyze their data and look for possible links between vitamin D, fish oil and cognitive function, autoimmune diseases, respiratory infections and depression. Previous research suggests that supplements may have an advantage for these conditions.

In the meantime, Lawrence Fine, an NIH official, says: do not throw away your fish oil and vitamin D.

"At this point, if you're thinking about omega-3 or vitamin D supplementation, talk to your doctor or health care provider, that's the next step," says Fine.

Fine and Manson have pointed out that vitamin D and omega-3 fatty acids found in fish oil are important nutrients, but that the best way to get them is to be part of a good diet. balanced. This includes eating fatty fish such as sardines, tuna and salmon, as well as cereals fortified with vitamin D, milk and orange juice.

Another study presented at the same meeting examined whether a substance derived from a fish oil component, called icosapent ethyl, could reduce adverse effects in people already having cardiovascular risk factors, such as as hardening of the arteries, diabetes or hypergolemia. known as triglycerides.

Overall, this study revealed a 25% reduction in risk in patients taking the extract. These researchers were less likely to die of heart disease, to have a heart attack or stroke, to be hospitalized for chest pain or to need procedures. such as angioplasty, stent graft or bypass, according to research.

"We report a remarkable degree of risk reduction," said Dr. Deepak Bhatt, head of the study and cardiologist at Brigham Hospital and Women & # 39; s.

The study, which was also a randomized clinical trial, followed participants for an average of five years. The volunteers took icosapent ethyl, sold under the brand name Vascepa and developed by Amarin Corporation, which funded Bhatt's research.

The product is available only on prescription for patients with high triglyceride levels. But the company should seek FDA approval over the next year to expand treatment to all high-risk cardiovascular patients.