Pictured Recipe: Spring Roll Salad
You know the omega-3 fatty acids in foods like salmon and flaxseed are good for you, but what about their less-talked-about cousin, omega-6s? We get this polyunsaturated fat from nuts, seeds and plant-based oils. Canola, peanut and sesame oils provide moderate amounts of omega-6s. Soy, corn, cottonseed, safflower and sunflower oils, are higher in omega-6 fats.
But while omega-3s are anti-inflammatory, omega-6s have a reputation for increasing inflammation and many people have been told to avoid omega-6 fatty acids. Now, several new studies suggest this decades-long bad rap may not be deserved.
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The advice to avoid omega-6s is rooted in anthropology. In the '90s, researchers noted that people were eating more omega-6s than previous generations did, and this dietary shift tracked closely with spikes in inflammatory health conditions, like heart disease and diabetes. So, they assumed (key word here!) that the omega-6s must be causing the uptick. This theory was bolstered by studies, predominantly in lab animals, showing that omega-6s from food (known as linoleic acid) can transform into arachidonic acid in the body, which goes on to make inflammatory compounds. Some scientists even suggested that we should eat a balance of "bad" omega-6s and "good" omega-3s closer to the 1:1 ratio our ancestors ate. (Currently, we get more 6s, in a ratio of 10:1.) Even though no major U.S. health organization advised limiting omega-6s, this group of researchers was vocal enough to plant this idea firmly in our heads.
Now, experts have found that theory to be false. Finnish scientists discovered that people with very low blood levels of omega-6s from linoleic acid had the highest levels of inflammatory markers—the opposite of what we'd been told. Not only does the inflammation claim fail to hold water, so do the links to disease. Harvard scientists found that replacing saturated fat with omega-6 fatty acids can reduce your odds of heart disease by 19 percent. And Canadian researchers found that swapping saturated fat with omega-6s also reduces LDL cholesterol. Plus, according to a review of 20 studies, people with higher levels of linoleic acid were less likely to develop type 2 diabetes than those with lower levels of this omega-6. Arachidonic acid levels didn't impact the disease either way.
Jyrki Virtanen, Ph.D., one of the University of Eastern Finland researchers studying omega-6s and inflammation, says that our previous understanding was far too simplistic. Yes, omega-6s can create inflammatory compounds. "However, that is only one side of the story," he says. "Arachidonic acid also creates molecules that reduce inflammation." And the body tightly regulates the process that converts linoleic acid into arachidonic acid. "People who recommend eating fewer omega-6s think—erroneously—that high linoleic acid intake increases arachidonic acid levels and inflammation. But only a tiny amount of linoleic acid converts to arachidonic acid." So, these fats aren't inflammatory villains and limiting how much you eat likely won't impact levels of arachidonic acid anyway.
Besides, the old assumption fails to look at the big picture. True, Americans get more omega-6s, in part because we're eating more processed foods, which are sources of these fats. However, pinning the concurrent rise in disease on omega-6s doesn't account for ingredients that may be the real culprits in these foods, like refined white flour and added sugars, which are known to promote inflammation.
It's still important to get omega-3s, but we don't need to demonize omega-6s, says Eric Rimm, Sc.D., professor of epidemiology and nutrition at Harvard: "Large, long-term studies show that omega-6s are some of the healthiest fats in the diet," he says. "People who have the most omega-6s in their diets even live the longest. That's a clear message to me that people should not be stressing about getting too much omega-6s." It is however, a good idea to cut back on processed foods and eat more whole foods.
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