By Rob Schick, PhD
For those of you who eat the typical American diet, one of the healthiest things you can do is reduce your intake of Omega-6 fatty acids and increase the amount of Omega-3 fatty acids you consume. Doing so may be good for your heart, and there’s evidence that it’s good for your brain. Eating more Omega-3s helps stave off depression and tendencies toward violence , and consuming more Omega-3s during pregnancy will make your kid smarter. Let’s look at why this is the case, and discuss how you can make some positive changes.
Many people who are active in the Paleo or ancestral diet community recommend a reduction of polyunsaturated fats (PUFA). What’s a PUFA? It’s a fat with at least 2 double bonds in the chemical structure of the molecule. Mono-unsaturated fats, like olive oil, have only one double bond. Saturated fats, like butter and coconut oil, have no double bonds. What are examples of PUFAs? Many vegetable oils that are so prolific in the American diet: soybean oil, canola oil, corn oil, and safflower oil. Now this is striking for me, because if you’re nearing 40, like I am, you’ve always heard that saturated fats are bad for your heart, and that oils like canola oil are “heart healthy.”
So why are some people claiming they’re unhealthy? Well, within the structure of a PUFA you have Omega-3 fatty acids, Omega-6 fatty acids, and Omega-9 fatty acids, with the number referring to the position of the double bond. Omega-3s are found in products like fish oil and flax seed. Omega-6s are found in beef, poultry, pork, nuts, and vegetable oils made from seeds. Omega-3s you’ve no doubt heard are good for you, as people from cultures with more fish in their diets tend to be healthier. But why are Omega-6s potentially the bad guys? When your body processes these fatty acids, they break them down and trigger a signaling process that typically leads to inflammation.
Ah ha! So here’s the issue. Both Omega-3s and Omega-6s are pro-inflammatory, that is, they lead to inflammation in the body, but Omega-6s are much more inflammatory than Omega-3s. So the more Omega-6s you have in your body, the more inflamed you will tend to be.
A recent paper by Balsbag et al., noted that in the 20th century there was a 1,000-fold increase in the amount of soybean oil consumed by Americans. In 1909, they estimate per capita consumption of soybean oil at 0.009 kg/person/year, but in 1999 Americans consumed 11.64 kg/person/year. That’s 25 pounds of soybean oil per person each year, and the bulk of it is coming from processed food.
Because we’re eating so many more of these fats, the ratio of Omega-6 to Omega-3 is increasing: it was 5.4 in 1909 and 9.6 in 1999. In other words, typical Americans are triggering more inflammation in their bodies today than we were a century ago.
A diet-related goal, then, is to have the ratio of these fatty acids in a healthy balance. If you’re eating the typical American diet, you can do this by minimizing your intake of Omega-6 fats – namely any modern seed oils found in processed foods such as salad dressings, mayonnaise, chips, popcorn, and crackers.
So what ratios should you be shooting for? Well it’s not clear that there’s an ideal number, but it is clear that a lower ratio of Omega-6s to Omega-3s is better. Consuming less of the Omega-6 fats does two important things: 1) it reduces your ratio, which is great, but 2) it allows for the Omega-3s to saturate your tissues more easily.
Omega-6s compete with Omega-3s in the signaling pathway by displacing the healthy Omega-3s from your tissue. So even if you eat more fish, that alone won’t necessarily lead to better overall health if you are still eating a lot of Omega-6s. Here’s a graphical snapshot of what this means to you health-wise. This graph (redrawn from Hibbeln et al., 2006) represents the relationship between Omega-3s in the diet and mortality in women from countries around the world:
What do you see? Women from countries that eat more fish, and fewer Omega-6 fats, tend to live longer, which in my book is a good thing. Hibbeln et al. (2006) use these data to present a predictive model of what you’d want to eat to get your tissues to look like those of someone from Japan, circled in blue on the lower right corner. The model factors intake of Omega-3s as well as background intake of Omega-6s. In the US, given our intake of linoleic acid (the predominant Omega-6 fat in our diet, representing 8.9% of calories consumed), you would need to eat around 3500 milligrams of Omega-3 fats. Remember the ratio, though. For someone who lives in Australia, where average linoleic acid intake is around 4.5%, they would only need to eat about 2 milligrams of Omega-3 fats. Someone in the Phillipines (0.8 % LA/day) would only need to eat 275 milligrams. The difference is huge, and the take home message is clear: restrict your intake of Omega-6 fatty acids as much as possible, and increase the amount of wild-caught fish and flax you are eating.