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Essential Fatty Acids: What You Need to Know (Part 3)
February 2, 2009
Talk about timing. Last week (in "Essential Fatty Acids: What You Need to Know [Part 2]"), I reviewed some key sources of omega-6 fatty acids: evening primrose oil, borage oil, and black currant oil. If you recall, these oils (which are typically taken as supplements) are prime sources of gamma-linolenic acid (GLA), one of the "good guy" omega-6’s that seems to have anti-inflammatory properties, helping with such conditions as rheumatoid arthritis, heart disease, diabetic neuropathy, and skin conditions like eczema and psoriasis.
Omega-6 fatty acids have traditionally been given a bad rap, however, and in the first part of this series, I mentioned how nutrition researchers are concerned about our “ratio” of omega-6 to omega-3 fatty acids. We apparently get too much of the former and not enough of the latter. But why, if some omega-6’s are good, are we told to cut back on our intake?
Arachidonic Acid: The Culprit?
AA is made from linoleic acid, but it’s also found in some of the food we eat, including eggs, meat, and fish. We need AA to form eicosanoids, hormone-like substances that play a role in inflammation, blood clotting, and blood vessel dilation. Prostaglandins, leukotrienes, and thromboxanes are examples of eicosanoids. Some eicosanoids are helpful in squelching inflammation (which is a good thing), whereas others, such as those made from AA, actually promote inflammation (not a good thing). You might be interested to know that some of the common drugs that we take work to block prostaglandins in the body, including aspirin, nonsteroidal anti-inflammatory drugs, or NSAIDS (such as ibuprofen), and some steroids.
Back to the timing, then. Just this past week, a position paper was published in Circulation, which is a journal of the American Heart Association. The committee that composed this “science advisory” consists of well-known nutrition scientists, some who are from Harvard University. Without focusing too much on the details, the basic premise of this paper is to refute the current thinking on omega-6 fatty acids and suggest, instead, that 5% to 10% of daily calories (or about 12 to 22 grams a day) should come from omega-6’s (remember that that includes most of the vegetables oils, such as corn, sunflower, safflower, and soybean oil, as well as nuts and seeds). You can download a PDF of the position paper here.
Why the sudden change of heart? The committee spent two years reviewing previous research and concluded that linoleic acid, an omega-6 fatty acid, may actually help lower LDL cholesterol and, therefore, lower the risk of heart disease. In addition, linoleic acid may help lower blood pressure and insulin resistance, thereby decreasing the risk of Type 2 diabetes. It will be interesting to see what the rest of the medical community has to say, as undoubtedly not everyone will agree with this committee’s conclusions.
Next week: Omega-3 fatty acids.
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