By Dennis Thompson
"Looking at the 17 randomized clinical trials that we combined, the majority of the trials -- especially the more recent and large-scale ones -- showed consistently little or no significant effect on reducing coronary heart disease events," said Dr. Rajiv Chowdhury, lead author of a comprehensive review of nutrition research related to fats.
Of the range of fats studied, only trans fats showed a clear negative effect on heart health, according to the review published in the March 18 Annals of Internal Medicine by Chowdhury, a cardiovascular epidemiologist at the University of Cambridge, and colleagues.
Trans fats can still be found in processed foods -- look for the words "hydrogenated" or "partially hydrogenated" in the ingredient list.
Saturated fats, long considered a dietary no-no, appeared to pose no additional risk for heart disease according to recent research, Chowdhury said. They carried about the same cardiac risk as unsaturated fats, omega-3 fatty acids and omega-6 fatty acids.
Saturated fats are solid at room temperature. They can be found in butter, lard, cheese and cream, as well as the fatty white areas on cuts of meat. By contrast, unsaturated fats are liquid at room temperature -- think of vegetable cooking oil or olive oil.
A second study also came to the same conclusion regarding omega-3 fatty acids, via a different route. This study had been reviewing the use of omega-3s for eye health, but researchers used their data to look at whether the supplements also helped prevent heart disease.
That study found no reduction in heart attack, stroke or heart failure among almost 1,100 people taking omega-3 supplements, compared to similar numbers of people taking other supplements for eye health or just an inactive placebo. It appeared online March 17 in JAMA Internal Medicine.
The meta-analysis performed by Chowdhury's team involved data from 72 studies with more than 600,000 participants from 18 nations. The team combined study findings to assess the heart health benefits of all types of dietary fat -- saturated fat, unsaturated fat, and the omega-3 and omega-6 fatty acids.
At the same time, omega-3 fatty acids were said to improve heart health because it increases your level of "good" HDL cholesterol. Good cholesterol is believed to help the body rid itself of bad cholesterol.
While this is still true, Chowdhury and his team found that neither effect seemed to make much difference for overall cardiac risk.
"Saturated fats are not essentially the main problem when it comes to risk of heart disease," Chowdhury said. "Also, omega-3 or omega-6 fatty acids have no or little impact on reducing cardiovascular disease outcomes."
The Council for Responsible Nutrition, a trade association representing the dietary supplement industry, released a statement calling the new report's viewpoint "potentially irresponsible" and accusing it of causing "nutritional guidance whiplash" for consumers.
"There are thousands of studies and decades of recommendations from government, academic, nutritional and medical organizations and experts supporting the important heart health benefits associated with diets high in polyunsaturated fats, low in saturated fats, and avoidance of trans fats," Duffy MacKay, a naturopathic doctor and the council's senior vice president of scientific and regulatory affairs, said in the prepared statement.
MacKay added that dietary recommendations from the American Heart Association and the federal government both emphasize the importance of omega-3 fatty acids in a person's diet.
Omega-3 fatty acids do play an important role in good nutrition, as do other unsaturated fats, study author Chowdhury noted.
"Omega-3 fatty acids are essential nutrients for health," Chowdhury said. "We need omega-3 fatty acids for numerous normal body functions, such as controlling blood clotting and building cell membranes in the brain."
But people should focus on getting their omega-3 fatty acids from food rather than through supplements, the researcher said.
Dr. Linda Van Horn, a professor of preventive medicine at Northwestern University Feinberg School of Medicine and a member of the nutrition committee of the American Heart Association (AHA), agreed.
"There is continuing data to support eating fish on a regular basis for heart health and other health benefits like [mental] function," Van Horn said. "There's no question that eating fish provides tremendous value in reducing risk for cardiovascular disease, but the use of a supplement -- whether it's a fish oil or any other nutrient -- really needs to be handled carefully."
People should keep their overall fat intake low because fats contain twice the calories of proteins or carbohydrates, according to federal guidelines.
Van Horn said the AHA's nutrition committee will review these new findings at its next meeting.
"I don't think we take any of these kind of findings lightly, nor would we recommend the benefit of a supplement ever over a heart-healthy diet," she said, noting that the new review is "further elaborating on nutrient data that weren't even available five or 10 years ago."
And, she added, "While there's a tendency for the American public to throw up their hands, the better way to interpret this is, 'How wonderful we have additional data and can look at these questions that previously went unanswered.'"
For his part, MacKay said the new studies will not alter the tips he provides his patients.
"If you want to play an active role in staying heart healthy, the best advice remains the same: Eat a healthy diet rich in polyunsaturated fats such as omega-3s, add omega-3 supplements if you're not eating enough fatty fish, and exercise regularly," MacKay said.