Wednesday, October 19, 2016
Wisdom Wednesday: Omega 3 Fatty Acids: DHA vs EPA
Chronic inflammation has been identified as a potential link between obesity and cardiovascular diseases. In people who are obese, fat cells release greater amounts of inflammatory and signaling molecules (adipokines) that induce insulin resistance, blood vessel dysfunction, and systemic inflammation, all of which increase the likelihood that an artery may become damaged. Once damaged, the artery will express proteins that attract white blood (immune) cells to the location to help with repair and recovery. These immune cells also begin secreting chemicals (cytokines) that signal more immune cells to come to their location.
Theoretically, the damage should resolve but that doesn’t happen because the chronic inflammation and dyslipidemia associated with obesity continually damages the arteries, never allowing them to fully repair. As the damage accelerates, LDL particles become trapped in the artery wall and become oxidized. Macrophages engulf the LDL particles creating “foam cells” and ultimately accumulate to form plague on the artery wall.
There is a growing body of literature suggesting that the omega-3 fatty acids EPA and DHA have the potential to reduce the inflammatory state associated with obesity. EPA and DHA serve as the precursor molecules from which anti-inflammatory compounds (resolvins, protectins and maresins) are synthesized. A recent meta-analysis of 68 randomized controlled trials showed that EPA and DHA supplementation significantly reduced several inflammatory molecules: tumor necrosis factor alpha, C-reactive protein and interleukin-6.
However, some studies used EPA and DHA in combination while others used only one of the fatty acids in isolation. A new double-blind, randomized placebo-controlled crossover study was recently published to try and differentiate the effects of these fatty acids. Men and women with abdominal obesity and low-grade inflammation consumed 2.7 grams of EPA, 2,7 grams of DHA, or three grams of corn oil for 10 weeks each. Inflammatory molecules, blood lipids, and body composition were assessed before and after each phase.
Compared to corn oil, DHA supplementation affected numerous inflammatory markers and blood lipids, including a significant reduction of CRP, whereas EPA was more limited in its effects.
With fish oil being one of the most widely used supplements, it is important not to start over-emphasizing DHA due to this one study. Studies like this should not be analyzed through the frame of a reductionist mindset. EPA and DHA exist together in nature and there are factors that may only respond to combined EPA and DHA consumption.
The omega-3 fatty acids are essential for human health because we cannot synthesize them. Just as we cannot manufacture the omega-6 fatty acids either. However, we can synthesize both EPA and DHA from other omega-3 fatty acids. So can many other animals.
But what about vegetable sources of omega-3 fatty acids? Flax seed oil is by far the richest but like all vegetable sources, it is devoid of EPA and DHA. Clinically, I find that the cleaner the patient’s diet, the more likely they are to efficiently convert ALA (alpha-linolenic acid) to either EPA or DHA. So the vegan eating organically grown plants typically can manufacture all the EPA and DHA they need.
The Bottom Line:
We must have adequate omega-3 fatty acids in our diet. Maybe DHA is more effective than EPA in reducing the risk of CVD, but I suggest ignoring the levels of both in your omega-3 supplement. However, if your diet is suspect, then look for the highest intake of DHA you can afford.
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