A genetic approach to examine the relationship between vitamin B12 status and metabolic traits in a South Asian population

Abstract

Background: Observational studies in South Asian populations have suggested an association between vitamin B12 status and metabolic traits; however, the findings have been inconclusive. Hence, the aim of the present study was to use a genetic approach to explore the relationship between metabolic traits and vitamin B12 status in a Sri Lankan population and to investigate whether these relationships were modified by dietary intake. Methods: A total of 109 Sinhalese adults (61 men and 48 women aged 25-50 years), from Colombo city underwent anthropometric, biochemical, dietary intake analysis and genetic tests. Genetic risk scores (GRS) based on 10 metabolic single nucleotide polymorphisms (SNPs) (metabolic-GRS) and 10 vitamin B12 SNPs (B12-GRS) were constructed. Results: The B12-GRS was significantly associated with serum vitamin B12 (P=0.008), but not with metabolic traits (P>0.05); whereas, the metabolic-GRS had no effect on metabolic traits (P>0.05) and vitamin B12 concentrations (P>0.05). An interaction was observed between B12-GRS and protein energy intake (%) on waist circumference (P=0.002). Interactions were also seen between the metabolic-GRS and carbohydrate energy intake (%) on waist to hip ratio (P=0.015). Conclusion: Our findings suggest that a genetically lowered vitamin B12 concentration may have an impact on central obesity in the presence of a dietary influence; however, our study failed to provide evidence for an impact of metabolic-GRS on lowering B12 concentrations. Given that our study has a small sample size, further large studies are required to confirm our findings.