Dietary fat and risk for advanced age-related macular degeneration

Objective:
To evaluate the relationship between intake of total and specific types of fat and risk for advanced age-related macular degeneration (AMD), the leading cause of irreversible blindness in adults.

Design:
A multicenter eye disease case-control study

Setting:
Five US clinical ophthalmology centers.

Patients:
Case subjects included 349 individuals (age range, 55-80 years) with the advanced, neovascular stage of AMD diagnosed within 1 year of their enrollment into the study who resided near a participating clinical center. Control subjects included 504 individuals without AMD but with other ocular diseases. Controls were from the same geographic areas as cases and were frequency-matched to cases by age and sex.

Main Outcome Measures:
Relative risk for AMD according to level of fat intake, controlling for cigarette smoking and other risk factors.

Results:
Higher vegetable fat consumption was associated with an elevated risk for AMD. After adjusting for age, sex, education, cigarette smoking, and other risk factors, the odds ratio (OR) was 2.22 (95% confidence interval [ CI] 1.32-3.74) for persons in the highest vs those in the lowest quintiles of intake (P for trend, .007). The risk for AMD was also significantly elevated for the highest vs lowest quintiles of intake of monounsaturated (OR, 1.71) and polyunsaturated (OR, 1.86) fats (Ps for trend, .03 and .03, respectively). Higher consumption of linoleic acid was also associated with a higher risk for AMD (P for trend, .02). Higher intake of omega-3 fatty acids was associated with a lower risk for AMD among individuals consuming diets low in linoleic acid, an omega -6 fatty acid (P for trend, .05; P for continuous variable,.03). Similarly, higher frequency of fish intake tended to reduce risk for AMD when the diet was low in linoleic acid (P for trend, .05). Conversely, neither omega-3 fatty acids nor fish intake were related to risk for AMD among people with high levels of linoleic acid intake.

Conclusion:
Higher intake of specific types of fat-including vegetable, monounsaturated, and polyunsaturated fats and linoleic acid-rather than total fat intake may be associated with a greater risk for advanced AMD. Diets high in omega-3 fatty acids and fish were inversely associated with risk for AMD when intake of linoleic acid was low.