Vitamin D deficiency and anemia: a cross-sectional study

Vitamin D has been suggested to have an effect on erythropoiesis. We sought to evaluate the prevalence of anemia in a population of individuals with vitamin D deficiency compared with those with normal levels in a population of a large integrated healthplan. A cross-sectional analysis in the period 1 January 2004 through 31 December 2006 of subjects with documented concurrent levels of 25-hydroxyvitamin D and hemoglobin were evaluated. Vitamin D deficiency was defined as <30 ng/mL and anemia was defined as a hemoglobin <11 g/dL. A total of 554 subjects were included in the analysis. Anemia was present in 49% of 25-hydroxyvitamin D-deficient subjects compared with 36% with normal 25-hydroxyvitamin D levels (p < 0.01). Odds ratio for anemia in subjects with 25-hydroxyvitamin D deficiency using logistic regressions and controlling for age, gender, and chronic kidney disease was 1.9 (95% CI 1.3–2.7). 25-hydroxyvitamin D-deficient subjects had a lower mean Hb (11.0 vs. 11.7; p = 0.12 ) and a higher prevalence of erythrocyte stimulating agent use (47% vs. 24%; p < 0.05). This study demonstrates an association of vitamin D deficiency and a greater risk of anemia, lower mean hemoglobin, and higher usage of erythrocyte-stimulating agents. Future randomized studies are warranted to examine whether vitamin D directly affects erythropoiesis

Quality of group interaction, ethnic group composition, and individual mathematical learning gains

High-quality helping behavior is essential for effective peer interaction and learning. This study focused on ethnic group composition and the quality of group interaction as predictors of individual mathematics performance. Video-observations of 92 fifth-grade students working in groups balanced on mathematics performance level were analyzed. We expected a difference in the quality of interaction and test scores of native and non-native students. Multilevel analysis identified process regulation and giving answers as positive predictors of mathematics performance, whereas giving or applying explanations contributed negatively. Non-native students generally had lower achievement scores than native students. Non-native students working in ethnically heterogeneous groups performed better than did students working in homogenous groups. Homogeneous groups used more high-quality helping behaviors and engaged more often in task-oriented behavior. Heterogeneous groups engaged more often in low-quality helping behaviors. Working with native students may have been conducive to non-native students’ understanding of word problems in realistic mathematics education