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D.R. Hoffman, D.K. H. Wheaton; Red Blood Cell Levels of Docosahexaenoic Acid (DHA) During Aging . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2104.
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© ARVO (1962-2015); The Authors (2016-present)
Randomized clinical trials have demonstrated that a dietary supply of the ω3 fatty acid, DHA, during infancy is important for optimal development of retinal and visual function. Numerous investigations also associate DHA with beneficial responses in adult diseases such as arthritis, cardiovascular disease, retinitis pigmentosa, and age–related macular degeneration (ARMD). Here we assess the distribution of ω3 and ω6 fatty acids in red blood cells (RBC) in humans through 8 decades of life.
Fasting blood samples were collected by venipuncture from 206 healthy volunteers (range: 4–82y). Individuals consuming >4 fish meals per week or taking fish oil/ DHA supplements were excluded. Following lipid extraction, methyl esters of thirty fatty acids from RBCs were quantified by gas chromatography (data reported as % total fatty acids).
RBC–DHA levels linearly increased by 30% from age 4 to 20 years then remained stable in adults at 4.05±0.94% (n=168; mean±SD). The correlation between DHA and age in the adult group was r=0.11 (p=0.15). Similarly, neither the arachidonic acid levels, the sum of all ω6 long–chain polyunsaturated fatty acids (LCPUFA), the sum of ω3 LCPUFAs, nor the ω6/ω3 LCPUFA ratio changed in this adult group as a function of age (p>0.7). No significant differences in any of the fatty acid indices were found between males and females (p<0.002 with Bonferroni correction). In a subset of the adult group diagnosed with ARMD (n=21), there was a non–significant increase in RBC–DHA (p>0.3; 4.35% vs 4.04%) compared to age–matched controls (n=28). In ARMD patients, no differences were found for the ω6 LCPUFA sum (22.1% vs. 22.4%); the ω3 LCPUFA sum (7.00% vs 6.92%); or the ω6/ω3 LCPUFA ratio (3.30 vs 3.36). No gender differences in the ARMD group were found in these fatty acid indices (p>0.4).
This characterization of blood fatty acid profiles during the aging process can serve as baseline data for comparison of fatty acids in patients with age–associated eye disease. Several epidemiological studies based on food frequency questionnaires suggest that consumption of DHA–rich foods can reduce the risk of advancing ARMD. We suggest that increasing the dietary supply of DHA and a resultant reduction in the ω6/ω3 fatty acid ratio leads to a healthier retinal cell membrane environment that may slow the progression of retinal degeneration in the aging population.
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