The American journal of clinical nutrition
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Several observational studies have shown that low serum vitamin B-12 is associated with increased body mass index (BMI) and adverse cardiometabolic outcomes. However, it is unclear if these associations reflect a causal effect of vitamin B-12 on cardiometabolic risk factors and diseases, latent confounding, or reverse causality. ⋯ We found no evidence that serum concentrations of vitamin B-12 are causally related to body weight or the majority of cardiometabolic outcomes investigated. However, vitamin B-12 may have a causal effect on fasting glucose and HOMA-B, although these results will require replication in large independent data sets. This trialwas registered at http://www.isrctn.com/ISRCTN47414943 as ISRCTN47414943.
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Adults and young children in countries experiencing the nutrition transition are known to be affected simultaneously by undernutrition and overnutrition. Adolescence is a critical period for growth and development. Yet, it is unknown to what extent this double burden of malnutrition affects adolescents in low- and middle-income countries (LMICs) and the macrolevel contextual factors associated with the double burden of malnutrition. ⋯ The double burden of malnutrition among adolescents in LMICs is common. Context-sensitive implementation and scale-up of interventions and policies for the double burden of malnutrition are needed to achieve the Sustainable Development Goal to end malnutrition in all of its forms by 2030. This trial was registered at clinicaltrials.gov as NCT03346473.