There is increasing evidence for a major role of nutrition in the etiology of age-related maculopathy (ARM). Among other factors (antioxidants, macular pigment), dietary fat may play an important role.1,2

HIGH FAT INTAKE, OBESITY
Several animal models have been developed that show that the combination of high fat intake and human variants of genes coding for apolipoproteins lead to modifications in the retina, similar to those observed in ARM. Epidemiological studies also suggest that obesity, disturbances of the lipid metabolism (ie, high plasma HDL cholesterol), and the apolipoprotein E4 allele increase the risk of developing ARM.2 This suggests that high fat intake probably has a role in the development of ARM in humans.

The retina is extremely rich in polyunsaturated fatty acids, in particular docosahexaenoic acid (DHA), a fatty acid in the omega-3 family. DHA, provided mainly by fatty fish, probably has structural, functional, and protective functions in the retina. Several epidemiological studies have suggested that patients who consume a diet high in DHA may be at reduced risk for ARM.3-5

Epidemiological data on the associations of ARM with type and quantity of dietary fat remain scarce and are partially inconsistent. Therefore, my colleagues and I investigated these associations with age-related eye diseases in the framework of a population-based study from the South of France called the Pathologies Oculaires Liées à l’Age (POLA Study).

POLA STUDY
The POLA study was conducted in Sète, a small harbor of the French Mediterranean. From 1995 to 1997, 2,584 patients aged ≥60 years underwent a complete ophthalmological examination, completed a questionnaire on risk factors, and had a fasting blood sample taken. From 1998 to 2000, 1,947 of 2,452 available patients participated in a follow-up examination.

A nutritional add-on study, POLANUT (Pathologies Oculaires Liées à l’Age and Nutrition), was conducted in survivors of the cohort aged ≥70 years between 2002 and 2003.6 Trained dietitians administered a food frequency questionnaire to 832 patients at their homes. Dietary fat intake was compared among patients with and without ARM, which was defined by the presence on the photographs taken at the follow-up examination of neovascular ARM, and/or geographic atrophy, and/or early ARM (ie, soft indistinct drusen [>125 µm] and/or soft distinct drusen [>125 µm] with pigmentary abnormalities).

We found that patients with high total fat intake had an almost fivefold increased risk for ARM (Figure 1), adjusting for age, gender, smoking, body mass index, and self-reported cardiovascular disease. Saturated and monounsaturated fats were similarly associated with an increased risk for ARM, although these associations were weaker. We found no association between ARM and polyunsaturated fat.

FOOD COMPOSITION
Because the food composition table used in the POLANUT Study did not include omega-3 and omega-6 fatty acids, my colleagues and I investigated the associations of fish intake with the risk of ARM, as fish is the main source of DHA. Total and white fish intakes were not significantly associated with the risk of ARM. By contrast, consuming fatty fish more than once a month was associated with a 60% reduced risk for ARM (odds ratio = 0.41, P=.01).

These results are consistent with previous studies, which have shown an increased risk for ARM in patients with high total fat intake and decreased risk among regular consumers of fish—and in particular among those consuming fatty fish. These results may lead to future dietary recommendations for the elderly that encourage decreased fat intake (which is excessive in Western countries) and increased fish intake (see sidebar, Dietary Sources of DHA and Omega-3 Fatty Acids). Clinical trials are ongoing to evaluate whether supplementation with DHA may decrease the risk of developing late ARM.

Cécile Delcourt, PhD, is a researcher with the team on Epidemiology of Nutrition and Food Behaviour at Inserm U593, University of Bordeaux 2, France. She may be reached at Cecile.Delcourt@isped.u-bordeaux2.fr.

1. Delcourt C. Dietary Fat and the Risk of Age-Related Maculopathy: The Polanut Study. Presented at the Association for Research and Vision in Ophthalmology Annual Meeting in Fort Lauderdale, Fla., May 6 to May 10, 2007.
2. Van Leeuwen R, Klaver CC, Vingerling JR, et al. Cholesterol and age-related macular degeneration: is there a link? Am J Ophthalmol. 2004;137:750-752.
3. Cho E, Hung S, Willett WC, et al. Prospective study of dietary fat and risk of age-related macular degeneration. Am J Clin Nutr. 2001;73:209-218.
4. Chua B, Flood V, Rochtchina E, et al. Dietary fatty acids and the five-year incidence of age-related maculopathy. Arch Ophthalmol. 2006;124:981-986.
5. SanGiovanni JP, Chew EY, Clemons TE, et al. The relationship of dietary lipid intake and age-related macular degeneration in a case-control study: AREDS Report No. 20. Arch Ophthalmol. 2007;125:671-679.
6. Delcourt C, Lacroux A, Carrier I, et al. Dietary Fat and the Risk of Age-Related Maculopathy: The Polanut Study. Euro J Clinl Nutr, advance online publication 14 February, 2007.