Omega-3 Fatty Acids, Particularly DHA, for the Brain

Q Is there evidence that omega-3 fatty acids improve cognitive function and brain function in general? Which is more helpful in this regard, EPA or DHA?

SAMEER, Balaton, MN

A Dutch researchers showed in the late 1990s that DHA and EPA are good for the brain by reducing the risk for dementia later in life.1 They found that consuming fatty fish significantly decreases the risk for dementia—Alzheimer’s disease in particular—in older individuals. These findings were extended recently, when the same researchers assessed the cognitive abilities of a younger group of individuals.2 In parallel with their earlier observations, they found compelling evidence that in middle-aged people, saturated fat and cholesterol are associated with an increased risk for cognitive impairment, whereas omega-3 fatty acids are associated with a reduced risk.

The authors summed up their findings by saying, “The most consistent findings from epidemiologic and clinical studies so far seem to be that cholesterol and (saturated) fat are positively, and fish and marine omega-3 PUFAs inversely, associated with dementia and cognitive impairment.”

While it is generally conceded that DHA is important for fetal and infant brain development (it’s frequently added to infants’ formulations), there is less certainty about that with regard to adults. There is, however, a growing body of evidence indicating that DHA plays a special role in helping to maintain general brain function. In this regard, DHA has been found to be important in several other physiological functions, including memory3 and neuroprotection.4

Aside from DHA’s important role as a component of brain-cell phospholipids (where it constitutes a significant part of the fatty acid content),5 an interesting aspect of its neuroprotective function involves the discovery of its molecular self-defense mechanisms.4 It produces a metabolite, neuroprotectin D1 (NPD1), that shows potent anti-inflammatory action as well as a strong neuroprotective action against oxidative cell damage and cell death. The researchers also discovered, however, that DHA itself, not just NPD1, is a strong inhibitor of oxidative stress-induced cell death, and they believe that DHA produces neuroprotective metabolites other than NPD1.

There have been no equivalent findings for EPA. At this time, it’s probably best to cover your bases and take fish oil containing both EPA and DHA. Moreover, in areas outside the brain, EPA continues to have a multitude of roles in maintaining health.

References

  1. Kalmijn S, Launer LJ, Ott A, Witteman JC, Hofman A, Breteler MM. Dietary fat intake and the risk of incident dementia in the Rotterdam Study. Ann Neurol 1997;42(5):776-82.
  2. Kalmijn S, van Boxtel MPJ, Ocké M, Verschuren WMM, Kromhout D, Launer LJ. Dietary intake of fatty acids and fish in relation to cognitive performance at middle age. Neurology 2004;62:275-80.
  3. Salem N Jr, Litman B, Kim HY, Gawrisch K. Mechanisms of action of docosahexaenoic acid in the nervous system. Lipids 2001;36:945-59.
  4. Kim HY, Akbar M, Lau A, Edsall L. Inhibition of neuronal apoptosis by docosahexaenoic acid (22:6n-3). Role of phosphatidylserine in antiapoptotic effect. J Biol Chem 2000; 275:35215-23.
  5. Lukiw WJ, Cui J-G, Marcheselli VL, Bodker M, Botkjaer A, Gotlinger K, Serhan CN, Bazan NG. A role for docosahexaenoic acid-derived neuroprotectin D1 in neural cell survival and Alzheimer disease. J Clin Invest 2005 Oct;115(10):2774-83.

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