Does the Ratio of Omega-3 to Omega-6 Matter?

07/16/2012 11:22 am ET | Updated Sep 15, 2012

For the last 40 years or so, we've been hearing that saturated fats (which are found in meat, butter, full-fat dairy, and certain tropical oils) are "artery-clogging," and that we should limit our intake of these fats to reduce our risk of heart disease. Over the last decade, however, there's been a steady drumbeat of dissent from researchers and renegades challenging this conventional wisdom.

Last year, the Academy of Food and Nutrition (previously known as the American Dietetic Association) invited several heavy hitters in the field of nutrition to debate the issue. The group, which included Walter Willet and Dariush Mozaffarian from Harvard and Alice Lichtenstein from Tufts, was only able to muster a fragile consensus: Maybe saturated fats aren't quite as bad as we've been led to believe. They also mostly agreed that telling people to cut back on saturated fats may do more harm than good if you're not very specific about what they should replace them with.

For example, we now know that the partially-hydrogenated vegetable oils in margarine are even worse for your heart than the saturated fats in butter. And low-fat diets that are high in refined carbohydrates not only contribute to heart disease risk but may contribute to Type 2 diabetes and obesity as well.

Is the Omega Ratio a Myth?

There was one thing, however, about which these experts were in complete and utter agreement -- that the ratio of omega-6 to omega-3 fats in the diet is totally unimportant. Omega-6 and omega-3, of course, are the two main families of polyunsaturated fats, or PUFAs. Omega-6 are found primarily in vegetable oils like corn and soybean oil; omega-3s are found in fish and flax seed. The modern, industrialized Western diet tends to be quite high in omega-6 and rather low in omega-3, and many nutrition experts have suggested that this is a problem. According to Dr. Willet, however, the idea that this ratio matters is a "myth ... without any data to support it."

As many of you know, I have talked about this ratio in previous articles and suggested that there is value in keeping the ratio of omega-6 to omega-3 from getting too high. A few of you may even have read my book on diet and inflammation, in which I talk about this as well. And I have to tell you that it was more than a little disconcerting to see this concept totally dismissed by some of the most respected and illustrious names in my field. Then again, you might also recall an article I wrote a couple years ago on how to find reliable sources of nutrition information in which I stated that:

"A good scientist is eager to abandon any position that's been proven false, no matter how strongly he might have held or argued that position previously."

So, in the interests of trying to live up to my own standards, I decided to review the evidence on this question and decide whether I needed to revise my position.

Plenty of Data to Support the Importance of Omega Ratio

Although you'd never have guessed it based on Dr. Willet's dismissive statement, it turns out there have been dozens of studies in the last few years aimed specifically at determining whether the ratio of omega-3 to omega-6 matters.

To be sure, many of these studies found no relationship between the omega ratio of the diet and various health outcomes. For example, it turns out the ratio of omega-6 and omega-3 in a mother's diet does not change the amount or distribution of fat in her baby. Good to know.

On the other hand, there was evidence that women who had a high ratio of omega-6 to omega-3 in their diets were more likely to suffer from post-partum depression. A high omega-6 to omega-3 ratio was also associated with increased risk of breast cancer in premenopausal women and -- in a different study -- with increased inflammation and fatigue in cancer survivors. Higher intake of omega-6 relative to omega-3 was also linked to an increased risk of macular degeneration, which is the leading cause of blindness in those over 55. The "high ratio" in most of these studies, by the way, is the ratio typical of the standard American diet.

With all these human studies, it seems like overkill to mention the study that found that a high intake of omega-6 promoted obesity in lab rats, an effect that was prevented when the ratio was adjusted by adding omega-3s to the mix. I also found a study linking a high ratio of omega-6 to increased inflammation in humans as well as a detailed analysis of multiple dietary intervention trials by scientists at the National Institutes of Health. The authors of that analysis -- prominent scientists in their own right -- concluded that advising people to replace saturated fats with PUFAs without regard to the ratio of omega-6 to omega-3 "may actually increase the risks of CHD and death."

What's the Bottom Line on Omega-6 Fats?

Do we know everything there is to know about how omega-6 fats affect our health? Of course not. But is the notion of an optimal ratio of omega-6 to omega-3 a myth with absolutely no data to support it? Hardly. I find it supremely ironic that this panel of experts -- even as they are admitting to decades of misguided advice on saturated fats -- feels perfectly comfortable dismissing valid questions about omega ratios as some sort of kooky, amateur obsession. Have we learned nothing?

I'm going to keep an open mind on this question -- and I wish our leading experts would do the same. In the meantime, I can't see any downside to moderating our intake of omega-6 fats (found mostly in processed foods) in favor of the uncontested benefits of omega-3s (found in fish) and monounsaturated fats (such as those in olive oil).

For more by Monica Reinagel, MS, LDN, CNS, click here.

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