Emilie Simon

Decreasing dietary linoleic acid promotes long chain omega-3 fatty acid incorporation into rat retina and modifies gene expression.

Age-related macular degeneration (AMD) may be partially prevented by dietary habits privileging the consumption of ω3 long chain polyunsaturated fatty acids (ω3s) while lowering linoleic acid (LA) intake. The present study aimed to document whether following these epidemiological guidelines would enrich the neurosensory retina and RPE with ω3s and modulate gene expression in the neurosensory retina. Rat progenitors and pups were fed with diets containing low or high LA, and low or high ω3s. After scotopic single flash and 8-Hz-Flicker electroretinography, rat pups were euthanized at adulthood. The fatty acid profile of the neurosensory retina, RPE, liver, adipose tissue and plasma was analyzed using gas chromatography. Gene expression was analyzed with real-time PCR in the neurosensory retina. Diets rich in ω3s efficiently improved the incorporation of ω3s into the organs and tissues. This raising effect was magnified by lowering LA intake. Compared to a diet with high LA and low ω3s, low LA diets significantly upregulated LDL-receptor gene expression. Similar but not significant upregulation of CD36, ABCA1, ALOX5 and ALOX12 gene expression was observed in rats fed with low LA. No effect was observed on retinal function. Increasing the intake in ω3s and lowering LA improved the enrichment with ω3s of the tissues, including the neurosensory retina and RPE, and upregulated genes involved in lipid trafficking in the neurosensory retina. Those results consistently reinforced the beneficial role of ω3s in the prevention of AMD, especially when the diet contained low levels of LA, as suggested from epidemiological data.

Problématiques de la nutrition en ophtalmologie – application à la dégénérescence maculaire liée à l’âge

« Que ton aliment soit ta seule medecine ». Cette citation d’Hippocrate est d’actualite aujourd’hui, plus encore qu’hier et particulierement en ophtalmologie. L’epidemiologie observationnelle rapporte des associations solides entre alimentation et risque ou prevention de certaines pathologies oculaires, comme la cataracte ou la Degenerescence Maculaire Liee a l’Âge (DMLA). Vitamines anti-oxydantes, mineraux et lipides sont les nutriments qui ont ete les plus etudies. L’epidemiologie interventionnelle et la recherche experimentale ont permis de corroborer un certain nombre de ces observations. De facon plus inattendue, le benefice d’une supplementation en acides gras omega 3 a longue chaine dans la prevention de l’evolution de la DMLA vers ses formes avancees n’a pas ete retrouve dans l’etude AREDS2 (Age-Related Eye Disease Study 2). Sans vouer aux gemonies plusieurs decennies de travaux dans ce domaine, les problematiques de la nutrition en ophtalmologie sont encore porteuses de decouvertes et d’espoirs, en particulier lorsque l’on considere le cadre plus large de l’alimentation et des relations genes-nutriments.

Serum omega-3 fatty acids are not associated with age-related macular degeneration

Evaluation of: Kabasawa S, Mori K, Horie-Inoue K et al. Associations of cigarette smoking but not serum fatty acids with age-related macular degeneration in a Japanese population. Ophthalmology 118(6), 1082–1088 (2011). Age-related macular degeneration (AMD) is the leading cause of visual impairment in the elderly in developed countries. Risk factors for AMD are classified into endogenous nonmodifiable factors, including genetics and environmental factors such as smoking and dietary habits. Both epidemiological and experimental studies suggest that dietary omega-3 long-chain fatty acids would participate to prevent from the development of AMD. The mechanisms behind this association have been poorly defined until now. Kabasawa and coworkers recently published that Japanese AMD patients did not exhibit a different serum fatty acid profile compared with Japanese controls, although the circulating levels of omega-3 fatty acids were doubled in Japanese subjects when compared with subjects in the USA – a consequence of Japanese dietary habits privileging fish consumption.