Major changes have taken place in our food supply over the past 100 years. Modern agriculture and technology have led to the development and use of polyunsaturated vegetable oils and changes in animal feeds from grass to grain, resulting in oils and foods that are higher in omega-6 fatty acids.
More recently, the link between saturated fat and heart disease has led many to move away from using butter and lard to using soybean and other plant oils, further increasing intake of omega-6 fatty acids. And that has some nutrition experts concerned.
Omega-6 and omega-3 fatty acids are unsaturated fats. But while omega-3 reduces inflammation in the body, omega-6 appears to increase it. Some research has also linked high omega-6 intake with increased leptin resistance (which lessens appetite control and the ability to burn fat) and insulin resistance (which increases the risk of diabetes).
In addition, high concentrations of omega-6 fatty acids in the blood increase the development of white adipose (fat) tissue and prevent it from browning, leading to higher risk for weight gain. Brown fat burns calories, white fat stores calories.
Some nutrition experts have begun to wonder if the obesity epidemic is related to the increase in omega-6 fatty acids in our diet. Should we limit the use of oils that contain omega-6 content of oils and switch to ones that are lower?
Not all experts have weighed in on this, and cutting sources of omega-6 fatty acids is controversial.
However, you should be aware that commonly used soybean oil (often simply labeled "vegetable" oil), corn, safflower, sunflower and walnut oils contain the highest amounts of omega-6. Animals raised on high omega-6 grains, such as corn and soy, produce meat, milk and eggs higher in omega-6 compared with grass-fed animals.
Which oils are lowest in omega-6 fatty acids? Olive, avocado, flaxseed and canola oils are. Do some of these oils also have significant amounts healthy omega-3 fatty acids? Yes, however, the human body isn't efficient in converting omega-3 in plants to forms the body can use.
This makes the ratio of omega-6 to omega-3 a fairly useless tool for evaluating oils. Plus the ratio masks the actual amounts of each type of fat. For example, a low ratio may appear appealing but still be higher in total omega-6 than other oils.
Instead, the amount of omega-6 (or omega-3) may be more helpful in choosing oils. For example, olive oil is a better choice than soybean oil because:
- While soybean oil has a fairly low ratio of omega-6 to omega-3, 100 grams (about 7 tablespoons) contains about 51 milligrams (mg) of omega-6 and 7 mg omega-3.
- Olive oil has a higher ratio of omega-6 to omega-3, but 100 grams has only about 10 mg of omega-6 and less than 1 mg of omega-3.
So what's a health-minded cook to do?
In my kitchen, it's time for an oil change. I'm going to switch to using oils lower in omega-6, like olive, avocado and canola, and use them in small amounts. Olive, avocado and canola oil are low in saturated fat (under 15 percent) and are good sources of healthy monounsaturared fat.
I'll continue to get my omega-3 fatty acids from fish (twice weekly) and small amounts of grass-fed meat, low-fat milk and eggs. These efforts are heart healthy — and may even help with weight control.
Feb. 07, 2017
- Simopoulos AP, DiNicolantonio JJ. The importance of a balanced omega-6 to omega-3 ratio in the prevention and management of obesity. Open Heart. 2016;3:e000385.
- Blasbalg TL, et al. Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century. American Journal of Clinical Nutrition; 2011;93:950.
- Anderson BM, Ma DW. Are all n-3 polyunsaturated fatty acids created equal? Lipids in Health and Disease. 2009;8:33.
- USDA National Nutrient Database for Standard Reference, Release 28. U.S. Department of Agriculture, Agricultural Research Service. http://ndb.nal.usda.gov. Accessed Feb. 2, 2017.