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Two Omega-3s Better than One
12/22/2011
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EPA and DHA exert synergistic effects; new studies confirm that both are needed for optimal heart health 
by Craig Weatherby 

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Growing evidence supports the notion that whole foodsnot supplementsare the healthiest way to get nutrients.
 
Six years ago, researchers from the USDA Nutrition Research Center at Tufts University wrote this in the Journal of the American Medical Association:
“The most promising data in the area of nutrition and positive health outcomes relate to dietary patterns, not nutrient supplements … [and suggest that] other factors in food … are more important than the level of individual nutrients consumed” (Lichtenstein AH, Russell RM 2005).
 
And in 2007, University of Minnesota scientists published an evidence review that favored whole foods over isolated nutrients … see “Whole Foods Seen Superior to Supplements”.
 
Key Points
  • New studies link DHA to healthier artery walls and EPA to reduced risk of congestive heart failure.
  • Prior studies suggest that both omega-3s can lower triglyceride and oxidative stress levels about equally, but that only DHA enhances artery health and reduces the risk of hypertension.
(That said, optimal levels of certain nutrients and beneficial food factorssuch as vitamin Dcan more easily or reliably be obtained from supplements.)
 
Judging by the outcomes of many clinical trials, the benefits of fish oil to heart health present an obvious exception to the “whole foods rule” principle.
 
No doubt, this is because omega-3 fatty acids provide most of the heart benefits associated with fish.
 
Still, to us and many researchers, fatty fish remains the preferred source of omega-3s … if you eat fatty fish at least twice a week.
 
This is because fatty fish provides other beneficial nutrients, such as selenium, vitamin D, andonly in wild salmonthe highly healthful orange pigment called astaxanthin.
 
A common omega-3 misconception
With regard to heart health, we commonly see claims that the omega-3 called EPA is more important than DHA ... its companion omega-3 in fish fat.
 
The makers of standard, chemically refined fish oils sometimes alter the proportions of EPA and DHA in their supplements to raise their supplements’ EPA content.
 
But there’s no good evidence that chemically altering the proportions of EPA and DHA in fish oil supplements actually enhances their heart-health effects.
 
(We never chemically refine or manipulate our naturally pure, “virgin” Wild Alaskan Sockeye Salmon Oil … which is exactly why some leading omega-3 researchers choose to it for their own use.)
 
A careful search of the biomedical literature undermines assertions that EPA is more important to heart health, with DHA and EPA appearing to offer distinct (and overlapping) benefits with regard to cardiovascular risk factors and outcomes.
 
In fact, the available evidence suggests that the two omega-3s work synergistically to reduce cardiovascular risks, via unique and shared effects.
 
Heart muscle accumulates more DHA than EPA, and these two omega-3s appear to exert different effects on blood stickiness, blood fat profiles, and artery health (e.g., arterial flexibility and inflammation status).
 
For example, in an Australian study of diabetic patients, supplemental DHAbut not EPAsignificantly reduced platelet aggregation (blood stickiness) … a major predictor and sign of cardiovascular disease (Woodman RJ et al. 2003).
 
And the same Aussie team found that DHA beat EPA when it came to enhancing artery health and reducing the closely associated risk of hypertension (Mori TA, Bao DQ, Burke V et al. 1999; Mori TA, Watts GF, Burke V et al. 2000).
 
When it comes to lowering triglyceride and oxidative stress levels, DHA and EPA exert similar beneficial effects (Mori TA, Burke V, Puddey IB et al. 2000; Mori TA, Woodman RJ, Burke V et al. 2003)
 
It’s important to note the human body can convert DHA to EPA, but cannot convert EPA to DHA.
 
In this senseand because DHA is far more important to brain, nerve, and eye healthit is always more important to ensure adequate intake of DHA … but for heart health, it’s ideal to get both, as we shall see.
 
(Humans can make DHAhence EPA as wellfrom the plant-source omega-3 called ALA. But this is a very inefficient process that’s impaired by diets high in omega-6 fatty acids from vegetable oils … such as the standard American diet.)
 
Now, the results of two separate studies strengthen the idea that both of the two omega-3s in whole fish and fish oilEPA and DHAare needed for optimal heart health.
 
Only DHA was linked to men’s artery health
A measure of artery-wall thickness called “carotid intima-media thickness” (CIMT) is linked to the presence and severity of atherosclerosis and the risk of cardiovascular disease.
 
A study in Spanish adults with unhealthful blood profiles (dyslipidemia) linked higher blood DHA levels to reduced CIMT (Sala-Vila A et al. 2010).
 
That finding was just confirmed by an “observational” study involving 310 middle-aged Japanese men and 298 U.S. caucasian men, all aged 40 to 49 and free of cardiovascular disease, but with some risk factors for CVD (Sekikawa A et al. 2011).
 
A team of researchers from Japanese and American universities compared the men’s CIMT values (thickness measurements) to blood levels of EPA and DHA, and other CVD risk factors.
 
The results showed that in both groups, higher DHA blood levelsbut not higher EPA levelswere linked to lower (healthier) CIMT values.
 
Having higher blood levels of the plant-source omega-3 called ALA was also linked to lower (healthier) CIMT values … but only in the US group, presumably because their EPA+DHA levels were so much lower than the Japanese levels, allowing dietary ALA to exert a more noticeable effect in the Americans.
 
Significantly, in this analysis, blood levels of DHA proved a reliable predictor of a man’s CIMT values. That is, higher DHA levels were linked to having lower (healthier) CIMT values.
 
The analysis also linked higher total omega-3 (EPA+DHA) blood levels to healthier (lower) CIMT values … but this association only appeared in the Japanese men, who had less atherosclerosis and double the omega-3 levels, compared with their US counterparts
 
Only EPA was linked to reduced risk of congestive heart failure
As we’ve said, DHA is linked to lower risk of key heart disease risk factors … but a new study finds that it doesn’t seem to reduce the risk of congestive heart failure.
 
In congestive heart failure (CHF), the heart is unable to pump sufficient blood … a condition that can develop from coronary artery disease, high blood pressure, obesity, or diabetes.
 
According to the American Heart Association, one in five people develop CHF after the age of 40, and about half will die within five years.
 
Some observational studies indicate that people who eat fish frequently are less likely to develop CHF. (See “Fish Cut Female Heart Failure; Fried Fish Raised Risk” and “Fish Oil Trial Finds More Heart-Failure Benefits”.)
 
Harvard researchers recently compared the fatty acid content of blood in people with CHF to that of people who didn’t develop heart failure, in a study involving 2,735 men and women who were followed for up to 14 years.
 
After seven years of follow-up, higher levels of EPA were linked to a significantly lower risk of CHF, with the risk being cut by about half in those with the highest EPA levels.
 
Smaller risk reductions were seen in those with the highest blood levels of DPA, and total long-chain omega-3s (EPA+DHA+DPA).
 
(DPA is a lesser known omega-3 that occurs at much lower levels in fish fat, compared with EPA and DHA. The body uses DPA to make DHA … or omega-6 fatty acids, if needed, which is rare among Americans. DPA’s role in health is just beginning to be explored, with exciting indications already appearing.)
 
In contrast, higher blood levels of DHA were not associated with a lower risk of CHF.
 
Nor was higher fish intake linked to lower CHF risk. This is not too surprising, since term "fish" was not defined, so it included lean and fatty fish, which have low and high levels of total omega-3s, respectively.
 
Further, each seafood species has a different ratio of EPA to DHA ... though most fish and fish oil supplements (including our salmon oil) have more EPA than DHA.
 
The outcomes of these two studies bolster the growing evidence that both DHA and EPA are needed to maximally reduce the risk of cardiovascular disease ... which usually precedes development of heart failure.
 
 
Sources
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  • Lichtenstein AH, Russell RM. Essential nutrients: food or supplements? Where should the emphasis be? JAMA. 2005 Jul 20;294(3):351-8.
  • Mori TA, Bao DQ, Burke V, Puddey IB, Beilin LJ. Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans. Hypertension. 1999 Aug;34(2):253-60.
  • Mori TA, Burke V, Puddey IB, Watts GF, O'Neal DN, Best JD, Beilin LJ. Purified eicosapentaenoic and docosahexaenoic acids have differential effects on serum lipids and lipoproteins, LDL particle size, glucose, and insulin in mildly hyperlipidemic men. Am J Clin Nutr. 2000 May;71(5):1085-94.
  • Mori TA, Watts GF, Burke V, Hilme E, Puddey IB, Beilin LJ. Differential effects of eicosapentaenoic acid and docosahexaenoic acid on vascular reactivity of the forearm microcirculation in hyperlipidemic, overweight men. Circulation. 2000 Sep 12;102(11):1264-9.
  • Mozaffarian D, Lemaitre RN, King IB, Song X, Spiegelman D, Sacks FM, Rimm EB, Siscovick DS. Circulating long-chain ω-3 fatty acids and incidence of congestive heart failure in older adults: the cardiovascular health study: a cohort study. Ann Intern Med 2011;155:160-170.
  • Sala-Vila A, Cofán M, Pérez-Heras A, Núñez I, Gilabert R, Junyent M, Mateo-Gallego R, Cenarro A, Civeira F, Ros E. Fatty acids in serum phospholipids and carotid intima-media thickness in Spanish subjects with primary dyslipidemia. Am J Clin Nutr. 2010 Jul;92(1):186-93. Epub 2010 May 12.
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