Pregnancy thiamine and riboflavin intake and the risk of gestational diabetes mellitus: A prospective cohort study.

BACKGROUND: Thiamine and riboflavin deficiencies exist to varying degrees worldwide, especially in developing countries. Evidence regarding the association between thiamine and riboflavin intake and gestational diabetes mellitus (GDM) is scarce. OBJECTIVES: We aimed to evaluate the association of thiamine and riboflavin intake during pregnancy, including dietary source and supplementation, with GDM risk in a prospective cohort study. METHODS: We included 3036 pregnant women (923 in the first trimester and 2113 in the second trimester) from the Tongji Birth Cohort. A validated semi-quantitative food frequency questionnaire and a lifestyle questionnaire were used to assess thiamine and riboflavin intake from dietary source and supplementation, respectively. GDM was diagnosed using the 75 g 2-h oral glucose tolerance test at 24-28 weeks of gestation. A modified Poisson regression or logistic regression model was used to evaluate the association between thiamine and riboflavin intake and GDM risk. RESULTS: Dietary intake of thiamine and riboflavin was at low levels during pregnancy. In the fully adjusted model, compared with participants in quartile 1 (Q1), those who had more total thiamine and riboflavin intake had a lower risk of GDM during the first trimester [thiamine: Q2: RR: 0.58 (95% CI: 0.34, 0.98); Q3: RR: 0.45 (95% CI: 0.24, 0.84); Q4: RR: 0.35 (95% CI: 0.17, 0.72), P for trend = 0.002; riboflavin: Q2: RR: 0.63 (95% CI: 0.37, 1.09); Q3: RR: 0.45 (95% CI: 0.24, 0.87); Q4: RR: 0.39 (95% CI: 0.19, 0.79), P for trend = 0.006]. This association was also observed during the second trimester. Similar results were observed for the association between thiamine and riboflavin supplement use but not dietary intake and GDM risk. CONCLUSIONS: Higher intake of thiamine and riboflavin during pregnancy is associated with a lower incidence of GDM. This trial was registered at http://www.chictr.org.cn as ChiCTR1800016908.

Vitamin D supplementation and lower respiratory tract infection in infants: a nested case-control study.

PURPOSE: To assess the association between vitamin D (VD) supplementation and the risk of lower respiratory tract infection (LRTI) among infants. METHODS: This is a nested case-control study from an ongoing prospective birth cohort in Wuhan from 2013. Cases were subjects free of neonatal pneumonia but later developed LRTI during infancy, who were matched with five randomly selected controls by infant sex, birth year, and birth season. We included 190 cases and 950 controls in the final analysis. The primary outcome was the first LRTI incident and the exposure was VD supplementation from birth to the index endpoint. The association between VD supplementation and LRTI risk was assessed using the Cox proportional-hazards regression model. RESULTS: Infants taking supplements had a 59% relative reduction in the hazard ratio of LRTI (HR = 0.41; 95% CI 0.26, 0.64) compared to those not supplemented. There was a linear relationship between LRTI risk and VD supplementation within range of 0-603 IU/day: for each 100 IU per day increment in VD supplementation, infants experienced a 21% lower risk of developing LRTI (adjusted HR: 0.79; 95% CI 0.71, 0.89). The linear relationship was stably observed in the sensitivity analyses as well. CONCLUSIONS: VD supplementation was associated with the reduced risk of LRTI throughout infancy, and the optimal supplementation dose for infants may be beyond the current recommendation.

Folic Acid Supplement Use and Increased Risk of Gestational Hypertension.

Current results regarding the effect of folic acid (FA) supplement use on gestational hypertension (GH) and preeclampsia are limited and inconsistent. We aimed to investigate whether FA supplement use was associated with GH and preeclampsia. Participants from the Tongji Maternal and Child Health Cohort with information on periconceptional FA supplement use and diagnosis of GH/preeclampsia were included (n=4853). Robust Poisson regression was used to assess the association of FA supplement use and GH and preeclampsia. Among the 4853 participants in this study, 1161 (23.9%) and 161 (3.3%) women were diagnosed with GH and preeclampsia, respectively. The risk ratio of developing GH was higher in women who used ≥800 µg/d FA supplement from prepregnancy through midpregnancy than nonusers (risk ratio, 1.33 [1.08-1.65]). After adjusting for social-demographic, reproductive, lifestyle factors, family history of hypertension, other supplement use, and gestational weight gain, the adverse association remained significant (risk ratio, 1.32 [1.06-1.64]). Restricting the analysis among women with normal weight, without family history of hypertension, and without gestational diabetes mellitus, the positive FA-GH association still existed. We did not find any significant association between FA supplement use and preeclampsia regardless of adjustment. High-dose (≥800 µg/d) FA supplement use from prepregnancy through midpregnancy was associated with increased risk of GH. Attention should be given to avoid the potential risk of GH due to inappropriate FA supplement use in women who are planning or capable of pregnancy.

Association of vitamin D supplementation with respiratory tract infection in infants.

Vitamin D deficiency has been reported to be associated with respiratory tract infection (RTI). However, evidence regarding the effects of vitamin D supplementation on susceptibility of infants to RTI is limited. In this prospective birth cohort study, we examined whether vitamin D supplementation reduced RTI risk in 2,244 infants completing the follow-up from birth to 6 months of age. The outcome endpoint was the first episode of paediatrician-diagnosed RTI or 6 months of age when no RTI event occurred. Infants receiving vitamin D supplements at a daily dose of 400-600 IU from birth to the outcome endpoint were defined as vitamin D supplementation and divided into four groups according to the average frequency of supplementation: 0, 1-2, 3-4, and 5-7 days/week. We evaluated the relationship between vitamin D supplementation and time to the first episode of RTI with Kaplan-Meier plots. The associations of vitamin D supplementation with infant RTI, lower RTI (LRTI), and RTI-related hospitalization were assessed using modified Poisson regression. The median time to first RTI episode was 60 days after birth (95% CI [60, 90]) for infants without supplementation and longer than 6 months of age for infants with supplementation (p < .001). We observed inverse trends between supplementation frequency and risk of RTI, LRTI, and RTI-related hospitalization (p for trend < .001), with the risk ratios in the 5-7 days/week supplementation group of 0.46 (95% CI [0.41, 0.50]), 0.17 (95% CI [0.13, 0.24]), and 0.18 (95% CI [0.12, 0.27]), respectively. These associations were significant and consistent in a subgroup analysis stratified by infant feeding.

Leucine Supplementation Differently Modulates Branched-Chain Amino Acid Catabolism, Mitochondrial Function and Metabolic Profiles at the Different Stage of Insulin Resistance in Rats on High-Fat Diet.

The available findings concerning the association between branched-chain amino acids (BCAAs)-particularly leucine-and insulin resistance are conflicting. BCAAs have been proposed to elicit different or even opposite effects, depending on the prevalence of catabolic and anabolic states. We tested the hypothesis that leucine supplementation may exert different effects at different stages of insulin resistance, to provide mechanistic insights into the role of leucine in the progression of insulin resistance. Male Sprague-Dawley rats were fed a normal chow diet, high-fat diet (HFD), HFD supplemented with 1.5% leucine, or HFD with a 20% calorie restriction for 24 or 32 weeks. Leucine supplementation led to abnormal catabolism of BCAA and the incompletely oxidized lipid species that contributed to mitochondrial dysfunction in skeletal muscle in HFD-fed rats in the early stage of insulin resistance (24 weeks). However, leucine supplementation induced no remarkable alternations in BCAA catabolism, but did enhance mitochondrial biogenesis with a concomitant improvement in lipid oxidation and mitochondrial function during the hyperglycaemia stage (32 weeks). These findings suggest that leucine trigger different effects on metabolic signatures at different stages of insulin resistance, and the overall metabolic status of the organisms should be carefully considered to potentiate the benefits of leucine.