(RxWiki News) To boost heart health, doctors have urged us for decades to eat fewer fats found in meat and dairy and more of the fats found in fish. A new study now seems to change that commonly given advice.
The American Heart Association guidelines say that people should limit the amount of meat, butter and cheese they eat because the saturated fats they contain raise the level of bad cholesterol in the blood. High cholesterol can lead to narrowing of the arteries. Eating fish rich in omega-3 fatty acids (polyunsaturated fats), on the other hand, has been shown to reduce cholesterol and boost cardiovascular health.
A new comprehensive study questions these guidelines, finding insufficient evidence to support restricting consumption of saturated fats or increasing consumption of polyunsaturated fats to reduce coronary risk.
"Exercise regularly and maintain a healthy weight to reduce heart risks."
Rajiv Chowdhury, MD, a cardiovascular epidemiologist at the University of Cambridge in England, led this research reviewing information from 72 studies concerning the consumption of fatty acids and relative risks for coronary disease.
In analyzing these studies, which represented more than 600,000 participants from 18 nations, scientists discovered that saturated fatty acid, whether measured in the diet or in the bloodstream, did not appear to be a factor related to heart disease risk.
When reviewing investigations dealing specifically with consumption of total monounsaturated fatty acids, long-chain omega-3 and omega-6 polyunsaturated fatty acids, the researchers could find no link between consumption and cardiovascular risk.
In looking at subsets of omega-3 and omega-6 acids, however, these researchers did find evidence that two main types of omega-3 polyunsaturated fatty acids and a type of omega-6 fatty acid were connected with reduced heart disease risk.
Supplements, however, did not seem to provide benefit. Trials of omega-3 and omega-6 fatty acid supplementations did not prove to have any significant effect on lowering heart disease, according to the authors of this review.
Also, common saturated fatty acids largely found in palm oils and animal fats did not appear to have a positive effect on heart disease risk, but the dairy fat margaric acid appeared to significantly reduce its likelihood.
"These are interesting results that potentially stimulate new lines of scientific inquiry and encourage careful reappraisal of our current nutritional guidelines,” said Dr. Chowdhury in a press release.
"While saturated fat may not be the culprit, there is little doubt that a diet high in red meat can contribute to a higher risk for heart disease and other health problems, including cancer," Sarah Samaan, MD, cardiologist and physician partner at the Baylor Heart Hospital in Plano, Texas, said to dailyRx News.
"Other studies have suggested that the way the body processes red meat, including byproducts of digestion, may make it harmful to our arteries. For that reason, choosing leaner cuts may not necessarily help. On the other hand, high fat foods contribute to obesity, itself a risk factor," said Dr. Samaan, who was not involved in this study.
"Fish is a leaner source of protein, and many studies have found that people who eat more fish tend to be healthier. Omega 3 supplements do not appear to be a good substitute for a healthy diet. Rather than trying to get your nutrition from pills, choose a diet that offers a wide range of naturally occurring nutrients to optimize your health and reduce the risk for heart disease, stroke, and cancer," she said.
Professor Jeremy Pearson, associate medical director at the British Heart Foundation (which helped fund the study), added in a statement, “This analysis of existing data suggests there isn’t enough evidence to say that a diet rich in polyunsaturated fats but low in saturated fats reduces the risk of cardiovascular disease. But large-scale clinical studies are needed, as these researchers recommend, before making a conclusive judgment.”
Professor Pearson recommended that that best way to maintain heart health, in addition to taking appropriate medication, is to stop smoking, stay active and follow a healthy whole-diet approach.
“This means considering not only the fats in our diet but also our intake of salt, sugar and fruit and vegetables,” Dr. Pearson said.
This study was published March 18 in the Annals of Internal Medicine. Funding was provided by grants from the British Heart Foundation, Medical Research Council, Cambridge National Institute for Health Research Biomedical Research Center and Gates Cambridge.