Background and Purpose: Despite zinc’s role as an antioxidant and anti-inflammatory agent, prospective studies relating zinc levels to ischemic stroke risk are lacking. To examine the association between serum zinc levels and incidence of ischemic stroke in a US population. Methods: Using a case–cohort study nested within the Reasons for Geographic and Racial Differences in Stroke cohort, participants were randomly selected from the Reasons for Geographic and Racial Differences in Stroke cohort to generate a sub-cohort (n=2346). All incident ischemic stroke cases as of September 2012 (n=660) were included, with 62 incident cases overlapping in the sub-cohort. Serum zinc levels were measured at baseline. Barlow-weighted Cox’s proportional hazards regression models were used to calculate multivariable-adjusted hazard ratios and the corresponding 95% CI of ischemic stroke by serum zinc levels. Results: The median zinc level for the sub-cohort was 121.19 µg/dL (interquartile range, 104.86–140.39 µg/dL). Serum zinc levels were inversely associated with incidence of ischemic stroke after adjustment for potential confounders (quartile 4 versus quartile 1: hazard ratio, 0.78 [95% CI, 0.61–0.98], P =0.03 for trend). When stratified by prespecified factors (sex, race, region), only sex showed a significant modification ( P =0.03 for interaction). The inverse association was more pronounced among females (quartile 4 versus quartile 1: hazard ratio, 0.58 [95% CI, 0.41–0.84], P <0.01 for trend) than males (quartile 4 versus quartile 1: hazard ratio, 1.08 [95% CI, 0.78–1.51], P =0.92 for trend). Conclusions: Serum zinc concentration was inversely associated with incidence of ischemic stroke, especially among women, indicating that low zinc levels may be a risk factor for ischemic stroke.

It is well established that breast milk is the ideal food for infants and that breastfeeding has short- and long-term health benefits for the mother and child. However, there is variation in breastfeeding patterns between populations. Women's work is thought to influence breastfeeding patterns and timing of supplementation and it is often assumed that women in subsistence-oriented societies can more easily integrate their productive and reproductive activities. This article reports longitudinal data, collected in three rounds (resguardo [<40 days], peak [2-4 months], and late [14-16 months] lactation), on breastfeeding structure, infant care, and work patterns of 17 rural Amazonian women in an effort to understand how breastfeeding structure and maternal time allocation changed over time, as well as the strategies women used to integrate their productive and reproductive roles. Women breastfed 10.6 ± 3.1, 9.4 ± 3.4, and 9.6 ± 5.5 times per 9-h period in the three rounds, respectively. Breastfeeding structure, specifically session duration, changed over time (P < 0.05). As lactation progressed, women spent less time breastfeeding and in infant care and more time in subsistence work. In peak lactation, subsistence work was negatively correlated with infant care (r = -0.4, P = 0.01), breastfeeding (r = -0.29, P = 0.05) and session duration (r = -0.39, P < 0.01) and in late lactation was negatively correlated with time spent breastfeeding (r = -0.39, P < 0.01) and in infant care (r = -0.50, P < 0.01) and positively correlated with inter-session interval (r = 0.40, P < 0.01). Generally, women reduced time in subsistence work when breastfeeding was more intense and returned to normal activity patterns once infants were being supplemented. The costs and benefits associated with women's strategies are discussed.

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Background and Purpose: Despite zinc’s role as an anti-oxidant and anti-inflammatory agent, prospective studies relating zinc levels to ischemic stroke risk are lacking. We aimed to examine the association between serum zinc levels and incidence of ischemic stroke in a US population. Methods: Using a case-cohort study nested within the REGARDS (REasons for Geographic and Racial Differences in Stroke) cohort, participants were randomly selected from the REGARDS cohort to generate a sub-cohort ( n= 2,346). All incident ischemic stroke cases as of September 2012 ( n =660) were included, with 62 incident cases overlapping in the sub-cohort. Serum zinc levels were measured at baseline. Barlow-weighted Cox’s proportional hazards regression models were used to calculate multivariable-adjusted hazard ratios (HR) and the corresponding 95% confidence intervals (CI) of ischemic stroke by serum zinc levels. Results: The median zinc level for the sub-cohort was 121.19 μg/dL (interquartile range 104.86 to 140.39 μg/dL). Serum zinc levels were inversely associated with incidence of ischemic stroke after adjustment for potential confounders (quartile 4 vs. quartile 1: HR=0.78, 95% CI: 0.61-0.98, p=0.03 for trend). When stratified by pre-specified factors (sex, race, region), only sex showed a significant modification (p=0.03 for interaction). The inverse association was more pronounced among females (quartile 4 vs. quartile 1: HR=0.58, 95% CI: 0.41-0.84, p<0.01 for trend) than males (quartile 4 vs. quartile 1: HR=1.08, 95% CI: 0.78-1.51, p=0.92 for trend). Conclusions: Serum zinc concentration was inversely associated with incidence of ischemic stroke, especially among women, indicating that low zinc levels may be a risk factor for ischemic stroke.