Abstract/Summary

Low vitamin B12 concentrations have been shown to be risk factors for metabolic traits in numerous observational studies; however, the relationship has remained inconsistent. It is possible that certain genotypes jointly contribute to obesity and vitamin B12 deficiency, and these may be modulated by dietary factors. The main objective of this review article was to summarize the effect of gene-nutrient interactions on vitamin B12 concentrations and cardio-metabolic disease risk factors using population-based studies from different ethnic groups from the GeNuIne (Gene-Nutrient Interactions) Collaboration. Interactions between vitamin B12-related SNPs and protein energy intake (%) on waist circumference (Pinteration=0.002) and body fat percentage (Pinteraction=0.034), were observed in Sri Lankan and Indonesian populations, respectively. In the study in Brazilian adolescents, the metabolic and vitamin B12 related SNPs showed a significant interaction with carbohydrate and protein intakes on oxidised low density lipoprotein cholesterol and homocysteine concentrations, respectively. In the Asian Indian population, an association between obesity-related SNPs and vitamin B12 concentrations (P = 0.018) was observed. In summary, these studies in multiple ethnic groups show that the association between genetically low vitamin B12 concentrations and metabolic outcomes may be modified by dietary intake. Further studies utilising larger sample sizes are needed to confirm or refute our findings.