Prospective study of zinc intake and the risk of age-related macular degeneration.
OBJECTIVE
Zinc is found in high concentrations in the retina and is hypothesized to reduce the risk of age-related macular degeneration (AMD). Any long-term benefit associated with dietary zinc intake has not been evaluated.


METHODS
We followed 66,572 women and 37,636 men who were > or = 50 years old and had no diagnosis of AMD or cancer. Zinc intake from food, multivitamins, and supplements was assessed with a semiquantitative food-frequency questionnaire at baseline (in 1984 for women and in 1986 for men) and repeated during follow-up (twice for women, once for men).


RESULTS
During 10 years of follow-up for women and 8 years of follow-up for men, we confirmed 384 incident cases of AMD (195 cases of the early form and 189 cases of the late form) associated with a visual acuity loss of 20/30 or worse. After multivariate adjustment for potential risk factors, the pooled relative risk was 1.13 (95% confidence interval [CI], 0.82 to 1.57; p-value, test for trend, 0.74) among participants in the highest quintile of total zinc intake (energy-adjusted median; 25.5 mg/day for women and 40.1 mg/day for men) compared with those in the lowest quintile (energy-adjusted median; 8.5 mg/day for women and 9.9 mg/day for men). The relative risk for highest compared with lowest quintile was 1.04 (95% CI, 0.59 to 1.83; p-value, test for trend, 0.54) for zinc intake from food. Subjects who took zinc supplements had a pooled multivariate relative risk of 1.04 (95% CI, 0.75 to 1.45).


CONCLUSIONS
In these two large prospective studies, moderate zinc intake, either in food or in supplements, was not associated with a reduced risk of AMD.
Cho
E
E
Departments of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA. eunyoung.cho@channing.harvard.edu
Stampfer
M J
MJ
Seddon
J M
JM
Hung
S
S
Spiegelman
D
D
Rimm
E B
EB
Willett
W C
WC
Hankinson
S E
SE
D000368:Aged; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008268:Macular Degeneration / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009726:Nurses / Q000706:statistics & numerical data; D011446:Prospective Studies; D012044:Regression Analysis; D012306:Risk; D014481:United States / Q000453:epidemiology; D015032:Zinc
D015032:Zinc