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The significant association between dietary calcium consumption and AMD risk indicates the need for further evaluation of dietary mineral elements in older adults in the US.
A new cross-sectional study investigated the relationship between dietary micronutrients and age-related macular degeneration (AMD) using a population of older adults in the United States from the National Health and Nutrition Examination survey.1
The results indicate that reduced consumption of dietary calcium was significantly associated with a higher risk of AMD, with more than half of the study population consuming an insufficient amount of calcium in their diet. As a result, investigators suggest a higher level of dietary calcium could lead to a lower occurrence of AMD.
“The possible beneficial effect of dietary calcium might be elucidated by other health habits of this population with a low incidence of AMD,” wrote investigators.1 “In general, those who have higher dietary or supplementary calcium intakes may have healthier diet habits and may be more inclined to take prescribed medications and exercise regularly. In addition, people with a healthier diet may have more dietary intakes of fish and lutein, which have been reported to be related to a decreased risk of AMD.”
The association between dietary micronutrients and the presence of AMD is not well-described in the literature. Led by Ying-Jen Chen, MD, PhD, Department of Ophthalmology, Tri-Service General Hospital, School of Medicine, National Defense Medical Center, the primary objective of the current analysis was to examine whether micronutrients had harmful or protective effects on AMD progression in the NHANES population from 2005 to 2008.
Approximately 5000 participants were evaluated and enrolled in the study. Investigators assessed AMD using fundus images and graded it into early AMD, intermediate AMD, or late AMD using the modified Wisconsin Age-Related Maculopathy Grading Classification Scheme.
The study collected mineral element consumption using two 24-hour dietary recalls, with analyzed dietary elements including magnesium, copper, zinc, sodium, calcium, and selenium. Using multivariable logistic regression, the associations between dietary mineral elements, serum concentration of calcium, and the presence of AMD were calculated and adjusted for relevant variables.
The study population consisted of 391 participants with AMD and 4728 participants without AMD, with a mean age of 70.20 and 58.33 years in each group, respectively. Investigators noted that participants with AMD had significantly lower dietary micronutrients, including calcium, magnesium, potassium, and selenium, as well as serum glucose, calcium, and higher serum C-reactive protein (P <.05).
After adjustment for relevant variables, the findings suggest dietary calcium was negatively associated with AMD (odds ratio [OR], 0.680; 95% confidence interval [CI], 0.482 - 0.960). By contrast, there was so significant relationship found between serum concentration of calcium and AMD, according to the data.
Moreover, after categorizing dietary calcium into tertiles, investigators found tertile 2 of dietary calcium had an inverse association with AMD (OR, 0.647; 95% CI, 0.452 - 0.928). The inverse relationship would remain significant after adjusting for age, gender, race, body mass index, serum laboratory data, medical history, and cigarette smoking status (OR, 0.694; 95% CI, 0.468 – 1.000).
Investigators stress the need for further research to confirm the relationship between AMD and dietary calcium consumption in order to modify general nutrition recommendations.
“Further studies are necessary to recognize the potential mechanism in altered calcium homeostasis in the pathogenesis of age-related diseases,” they added.1