A genetic approach to examine the relationship between vitamin B 12 status and metabolic traits in a South Asian population

Background Observational studies in South Asian populations have suggested an association between vitamin B 12 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 B 12 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 and biochemical measurements, dietary intake analysis, and genetic tests. Genetic risk scores (GRS) based on 10 metabolic single nucleotide polymorphisms (SNPs) (metabolic-GRS) and 10 vitamin B 12 SNPs (B12-GRS) were constructed. Results The B12-GRS was significantly associated with serum vitamin B 12 ( 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 B 12 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 B 12 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 B 12 concentrations. Given that our study has a small sample size, further large studies are required to confirm our findings.