Faculty Bibliography

Since 1980, at least 9 studies have assessed the potential associations between zinc supplementation and cognitive development in human infants and children. This article provides a brief review of the literature on the roles of zinc and its proposed associations with cognition. At present, the body of evidence is insufficient to warrant recommending routine zinc supplementation to enhance cognitive performance among children. In the United States and internationally, there are few available data on zinc status or deficiency rates in children and further study is necessary to assess the efficacy of zinc supplementation, alone or in combination with other nutrients, for improving cognitive outcomes. |

Amount and type of dietary fat may play a role in the pathogenesis of age-related macular degeneration (AMD) via 4 potential mechanisms: (1) atherosclerosis, (2) altering retinal integrity, (3) oxidative damage, and (4) inflammation. In this report, 11 epidemiologic studies are evaluated for evidence of associations between dietary fats and AMD. Taken together, the studies suggest a protective association of higher omega-3 polyunsaturated fats and fish intake with AMD. The relations of AMD with total and types of fat varied across populations and may reflect different patterns of fat intake. Practitioners should advise a low-fat, "heart-healthy" diet and encourage consumption of diets high in omega-3 polyunsaturated fats.|

Studies suggest inverse associations between obesity and prostate-specific antigen (PSA). However, there is little evidence whether factors related to obesity, including lifestyle (diet and physical activity) and physiologic factors (insulin resistance and metabolic syndrome), influence PSA. We used dietary, physical activity, and serum PSA, insulin, glucose, and lipid data for men >40 years from the National Health and Nutrition Examination Survey (2001-2004; N = 2,548). Energy, fat, and carbohydrate intakes were estimated from a 24-hour dietary recall. Men were considered as having metabolic syndrome based on the Adult Treatment Panel III criteria. Leisure-time physical activity and doctor-diagnosed hypertension were self-reported. Body mass index was calculated from measured weight and height. We computed the geometric mean PSA (ng/mL), adjusted for age, race, and body mass index, by tertile of energy, fat, and carbohydrate intake and level of physical activity, and among men with and without insulin resistance and metabolic syndrome in the whole population and by race. The geometric mean PSA (95% confidence interval) among men in the lowest tertile of energy was 1.05 (0.97-1.1) relative to 0.85 (0.8-0.9) in the highest tertile (P = 0.0002) in the whole population. The PSA concentrations were lower among overweight men with higher versus lower energy intake (P = 0.001). The PSA concentrations in men with insulin resistance was lower [0.87 (0.8-0.9)] relative to men without insulin resistance [0.98 (0.9-1.1)] at P = 0.04. All associations were in similar directions within racial subgroups. No associations were observed between the other lifestyle and physiologic factors. Additional studies are required to confirm these results and to investigate the potential mechanisms that may explain these relationships.

OBJECTIVE: To evaluate associations between nuclear cataract (determined from slitlamp photographs between May 2001 and January 2004) and lutein and zeaxanthin in the diet and serum in patients between 1994 and 1998 and macula between 2001 and 2004. DESIGN: A total of 1802 women aged 50 to 79 years in Iowa, Wisconsin, and Oregon with intakes of lutein and zeaxanthin above the 78th (high) and below the 28th (low) percentiles in the Women's Health Initiative Observational Study (1994-1998) were recruited 4 to 7 years later (2001-2004) into the Carotenoids in Age-Related Eye Disease Study. RESULTS: Women in the group with high dietary levels of lutein and zeaxanthin had a 23% lower prevalence of nuclear cataract (age-adjusted odds ratio, 0.77; 95% confidence interval, 0.62-0.96) compared with those with low levels. Multivariable adjustment slightly attenuated the association (odds ratio, 0.81; 95% confidence interval, 0.65-1.01). Women in the highest quintile category of diet or serum levels of lutein and zeaxanthin as compared with those in the lowest quintile category were 32% less likely to have nuclear cataract (multivariable-adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.97; P for trend = .04; and multivariable-adjusted odds ratio, 0.68; 95% confidence interval, 0.47-0.98; P for trend = .01, respectively). Cross-sectional associations with macular pigment density were inverse but not statistically significant. CONCLUSIONS: Diets rich in lutein and zeaxanthin are moderately associated with decreased prevalence of nuclear cataract in older women. However, other protective aspects of such diets may in part explain these relationships.

OBJECTIVE: To evaluate the associations between levels of vitamin D (25-hydroxyvitamin D) in serum and prevalent age-related macular degeneration (AMD). METHODS AND DESIGN: Cross-sectional associations of serum vitamin D and early and advanced AMD, assessed from nonmydriatic fundus photographs, were evaluated in the third National Health and Nutrition Examination Survey, a multistage nationally representative probability sample of noninstitutionalized individuals (N = 7752; 11% with AMD). RESULTS: Levels of serum vitamin D were inversely associated with early AMD but not advanced AMD. The odds ratio (OR) and 95% confidence interval (CI) for early AMD among participants in the highest vs lowest quintile of serum vitamin D was 0.64 (95% CI, 0.5-0.8; P trend <.001). Exploratory analyses were conducted to evaluate associations with important food and supplemental sources of vitamin D. Milk intake was inversely associated with early AMD (OR, 0.75; 95% CI, 0.6-0.9). Fish intake was inversely associated with advanced AMD (OR, 0.41; 95% CI, 0.2-0.9). Consistent use vs nonuse of vitamin D from supplements was inversely associated with early AMD only in individuals who did not consume milk daily (early AMD: OR, 0.67; 95% CI, 0.5-0.9). CONCLUSION: This study provides evidence that vitamin D may protect against AMD. Additional studies are needed to confirm these findings.

OBJECTIVE: To evaluate the relationship between dietary lutein plus zeaxanthin and intermediate age-related macular degeneration (AMD). DESIGN: Women aged 50 to 79 years in Iowa, Wisconsin, and Oregon with intake of lutein plus zeaxanthin above the 78th (high) and below the 28th (low) percentiles at baseline in the Women's Health Initiative Observational Study were recruited 4 to 7 years later into the Carotenoids in Age-Related Eye Disease Study (CAREDS), when the presence of AMD was determined by fundus photographs. Logistic regression analyses examined the prevalence of AMD in 1787 CAREDS participants, after accounting for potential covariates. RESULTS: The prevalence of intermediate AMD was not statistically different between the high and low lutein plus zeaxanthin intake recruitment groups after adjusting for age (odds ratio, 0.96; 95% confidence interval, 0.75-1.23). Limiting analyses to women younger than 75 years with stable intake of lutein plus zeaxanthin, without a history of chronic diseases that are often associated with diet changes, substantially lowered odds ratios (0.57; 95% confidence interval, 0.34-0.95). Exploratory analyses of advanced AMD in 34 participants resulted in protective, but statistically nonsignificant, associations in the overall sample and in women younger than 75 years. CONCLUSION: Diets rich in lutein plus zeaxanthin may protect against intermediate AMD in healthy women younger than 75 years.