People who replace saturated fat and trans fat with unsaturated fat may increase their chances of living longer, according to a recent study from the Harvard T.H. Chan School of Public Health. Analyzing 126,233 subjects for more than 30 years, the research is the most detailed examination yet about how dietary fats impact health, the university said in a release.
"There has been widespread confusion in the biomedical community and the general public in the last couple of years about the health effects of specific types of fat in the diet," said Dong Wang, a doctoral candidate in the Departments of Nutrition and Epidemiology at Harvard Chan School and lead author of the study. For example, a review of research published earlier this year in BMJ found no clear association between higher intake of saturated fats and death for any reason.
The new study "documents important benefits of unsaturated fats, especially when they replace saturated and trans fats," said Wang. The researchers looked at participants’ ages and causes of death, and their intake of saturated, unsaturated fats and trans fats; each had a different association with mortality.
The intake of high amounts of unsaturated fats (both polyunsaturated and monounsaturated) was associated with between 11 percent to 19 percent lower overall mortality, compared with the same number of calories from carbs. Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death.
People who replaced saturated fats with unsaturated fats—especially polyunsaturated fats—had significantly lower risk of death overall during the study period, as well as a lower risk of death from cardiovascular disease, cancer, neurodegenerative disease and respiratory disease, compared with those who maintained high intakes of saturated fats. The results were published in JAMA Internal Medicine.
"Our study shows the importance of eliminating trans fat and replacing saturated fat with unsaturated fats, including both omega-6 and omega-3 polyunsaturated fatty acids. In practice, this can be achieved by replacing animal fats with a variety of liquid vegetable oils," senior author Frank Hu, professor of nutrition and epidemiology at Harvard Chan School and professor of medicine at Harvard Medical School, said in the release.