Elderly Subjects with Cataracts Found to have Reduced Levels of DHA in their Circulation
Chang , D. et al., J. of the Amer. College of Nutrition, 33: 406-411,2014
Public Health School, Harbin Medical University, Harbin, China
Cataracts are present in approximately one-half of the population by the age of 70. The clouding of the lens inside the eye leads to a decrease in vision. Those who are in a position to be treated surgically via lens extraction generally have a good outcome. Because of the huge medical expenditures associated with cataract surgery as the population ages, there is much interest in determining lifestyle and dietary factors which could both increase the health status of the elderly and delay or prevent cataract development. Since measures of omega-3 fatty acids in the blood reflect both intakes of these fatty acids and their status in the body, the present research study compared their levels in 50 healthy controls with 50 patients having cataracts (with an average age of 60 years). The levels of the various fatty acids in the blood serum samples were determined by gas chromatography-mass spectrometric technology.
With respect to the omega-3 fatty acid analyses, the total summed omega-3 levels were found to be significantly lower (by 26 %) and the DHA omega-3 (docosahexaenoic acid) was lower (by 39 % overall) in the circulation of the patients with cataracts as compared to the healthy controls. Interestingly, neither the levels of the short-chain omega-3 (alpha-linolenic acid) or EPA (eicosapentaenoic acid) were different between the two groups of subjects. The authors suggested that the type of dietary fatty acids consumed could alter the fatty acid composition of the cell membranes in the lens which can influence cataract development.
Dr. Holub's Comments:
It is well known that the high concentration of DHA omega-3 in the retinal membranes of the eye supports the photoreceptive process and optimal visual acuity via various mechanisms (including rhodopsin behavior and function, anti-inflammatory effects, others). The higher levels of circulating DHA in the healthy controls free of cataracts are consistent with population studies indicating that higher intakes of fish containing DHA omega-3 are inversely associated with the risk of cataract extraction (Lu et al., Amer. J. Epidemiol., 161: 948-959 (2005)). The optimal intake of long-chain omega-3 fatty acids from fish/seafood, functional foods, or via supplementation for the prevention or delay of cataract formation in the aging population remains to be clarified.