"Enduring dietary wisdom  that polyunsaturated vegetable fats are better for your heart than saturated animal fats  may be turned on its head by a fresh analysis of a nearly yearold study.    The reasoning has been that a diet rich in omega polyunsaturated fats lowers cholesterol and is therefore good for heart health. But an updated look at the study indicates that heart disease patients who follow this advice may actually increase their risk for death.    The original Sydney Diet Heart Study was initially conducted between  and  at a time when the cholesterollowering benefits of all polyunsaturated vegetable acids PUFAs were touted with a broad brush.    But in the ensuing years researchers have come to understand that not all PUFAs are alike with key biochemical differences  and perhaps varying cardiovascular impacts  observed among multiple types of omegas found in fish oils and omega linoleic acids.    There is more than one type of polyunsaturated fatty acid explained Dr. Christopher Ramsden who headed the reanalysis and is a clinical investigator with the laboratory of membrane biophysics and biochemistry at the National Institute on Alcohol Abuse and Alcoholism part of the U.S. National Institutes of Health.    And so we were interested in trying to evaluate just one of these compounds linoleic acid by looking at this old trial using modern statistical methods and also by reincluding some original data that had gone missing from the first analysis Ramsden explained.    The findings appeared online Feb.  in the BMJ.    The  male participants in the original study had been between the ages of  and  at enrollment and all had a history of heart disease with most having survived a heart attack.    The men were placed into two groups. The first group was told to consume linoleic acid in the form of safflower oil and safflower oil polyunsaturated margarine at levels equal to  percent of total calorie intake. This said Ramsden is equivalent to roughly twice the amount that Americans currently consume.    While omega consumption was not affected the men were also asked to lower their saturated fat intake so that it made up less than  percent of their diets. They did so by substituting safflower oil for animal fats common margarines and shortening oils salad dressings baked goods and other products according to the study.    The second group continued their routine nutritional habits and both groups kept food diaries and underwent regular assessments during the threeyearplus study period.    By newly crunching all the original data the NIH team found that compared to the nodietarychange group the linoleic acid group faced a higher risk of death from both heart disease specifically as well as from all causes overall.    In turn Ramsdens investigators included their Sydney conclusions in a new review of all studies to date exploring the impact of omega consumption.    Despite the fact the American Heart Association AHA currently recommends that  percent to  percent of all calories come from polyunsaturated fat principally from omega the NIH team found no evidence to support the notion that linoleic acid confers health benefits. The review highlighted the possibility that boosting omega consumption may actually increase the risk for developing heart disease.    Ramsden acknowledged that the Sydney study had been narrowly focused on a specific group of people middleaged men with a history of heart disease who were asked to consume linoleic acid in quantities far exceeding both AHA guidelines and the dietary habits of most Americans.    So yes one of the limitations of this kind of study is always the question of its generalizability to other populations he cautioned.    But he also suggested that his teams rigorous look back offered valuable insights into how nutritional science has evolved.    What to many people had at one time seemed pretty straightforward in the s has turned out to form a much less blackandwhite picture he said. Polyunsaturates are not just involved in cholesterollowering. They may also be involved in inflammation oxidation or clotting. So its a very complex picture. And though our goal is not to come up with diet advice it may be that our conclusions will have important implications for nutritional guidelines.    On that score American Heart Association spokesperson Penny KrisEtherton a registered dietician and professor of nutrition at Pennsylvania State University suggested that the controversy concerning linoleic acid is not new and will continue.    But I dont think this is going to change AHA recommendations she said. Because theres very robust evidence showing the cardiovascular benefit of linoleic acid. The AHA science advisory board did not just look at one study or a couple of studies. There are lots of studies that form the basis for their guidelines.    So I dont think anybody should get alarmed and change their diet KrisEtherton said. Those who are concerned should wait for more research to come out on this topic before taking any drastic measures to change their eating habits in a way that could be harmful.    More information For more on AHA guidelines regarding linoleic acid visit the American Heart Association httpcirc.ahajournals.orgcontent.full.pdf. SOURCES Christopher Ramsden M.D. clinical investigator Laboratory of Membrane Biophysics and Biochemistry National Institute on Alcohol Abuse and Alcoholism U.S. National Institutes of Health Bethesda Md. Penny M. KrisEtherton Ph.D. R.D. professor of nutrition Pennsylvania State University and American Heart Association spokesperson Feb.   BMJ."