The American Heart Association (AHA) recently released a Scientific Advisory that examined the connections between omega-6 fatty acids and heart health. Food Insight interviewed Bill Harris, PhD, one of the lead authors on the AHA Advisory to find out more about this report. Dr. Harris holds a PhD in Nutritional Biochemistry from the University of Minnesota. He is currently Director of the Cardiovascular Health Research Center at Sanford Research/ University of South Dakota and is a Research Professor of Medicine at the Sanford School of Medicine, University of South Dakota.
This article will focus primarily on omega-6 fatty acids. For a primer on dietary fats and additional information on why these questions are being raised see: Background on Dietary Fats.
Q: Why did the American Heart Association evaluate omega-6s and heart health?
A: There have been some popular nutrition books in the U.S. and elsewhere that have recommended that people should reduce their consumption of omega-6 fatty acids. This grew out of a debate among researchers about the need to define a specific “healthy” omega-6 to omega-3 ratio. There are various ways to adjust the ratio: if it is too high, you can lower the omega-6s, or you can increase the amount of omega-3s, or you can do both. However, the only approach that will truly lower coronary heart disease risk is to raise the omega-3s, specifically DHA/EPA. What I saw was that people were cutting back on their consumption of omega-6s rather than increasing their omega-3s and that wasn’t providing the same health benefit. If people continue to do this, rates of CVD may actually increase, which would have a negative impact on public health. We at the AHA were concerned, so we decided to review the literature.
Q: How much of a person’s daily calorie intake should come from omega-6s, and what foods provide them?
A: Anywhere from 20 to 35 percent of an individual’s daily calorie intake should come from fat. Ideally, sources of unsaturated fats, including omega-6 fatty acids, should replace saturated and trans fats in the diet. However, saturated and unsaturated fats exist in foods together in a matrix, so it may be difficult to completely eliminate saturated fats from the diet. Current dietary guidance recommends that saturated fats be kept below 10 percent of total daily calorie intake and trans fats should be consumed sparingly. Specific to omega-6, linoleic acid intake should be anywhere between five percent and 10 percent of calories. Sources of omega-6 fatty acids include vegetable oils, nuts, seeds, and certain salad dressings.
Q: What would you like to see achieved from the release of this statement?
A: I would like to see more nutrition and health organizations recognize the role that omega-6 fatty acids play in maintaining heart health. It would be helpful for all professionals who are communicating about nutrition and heart health to deliver consistent dietary advice about omega-6 fats.
Q: What were the findings from the Scientific Advisory?
A: The bottom line is that in order to avoid increasing their cardiovascular disease (CVD) risk, people should maintain current intakes of omega-6 fatty acids. The studies that we reviewed pointed pretty consistently to a cardio-protective effect of omega-6 fatty acids. When I refer to omega-6s, I am predominately talking about a specific type of omega-6 known as linoleic acid. This particular type of omega-6 is essential, meaning the body cannot produce it, so it must be consumed through the dietary sources.
Q: If you could provide one recommendation to Americans what would it be?
A: It’s important to remember to focus on an overall healthy dietary pattern – one nutrient or one type of fat is not a magic bullet for good health. Americans need to view all of the “omega” fats, whether omega-3 or omega-6 (all of which are unsaturated fats), as an important part of a heart healthy diet. The unsaturated fats are all very good for you. The things to limit are the saturated fats and trans fat.
AHA Scientific Advisory Highlights*:
- Most people should consume at least five to 10 percent of their total daily calories from omega-6 fatty acids.
- Replacing saturated fats with poly-unsaturated fats, which are natural sources of omega-6 and omega-3, will help reduce heart disease risk.
- Higher intakes of omega-6s may improve insulin resistance, reduce diabetes risk and lower blood pressure.
*Adapted from the American Heart Association Web site: http://www.americanheart.org/
Over the past 30 years, Dr. Harris' research has primarily focused on omega-3 fatty acids and cardiovascular disease. He has been the principal investigator on five omega-3 related NIH grants, and is currently evaluating blood tests of low levels of omega-3 as a possible new risk factor for cardiovascular disease and cognitive decline in the Framingham Offspring cohort and in the Women’s Health Initiative Memory Study. He has authored more than 150 peer-reviewed research publications.