Long-term exposure to high levels of B vitamins (niacin, thiamin, riboflavin) may be involved in the increased prevalence of obesity and type 2 diabetes in the United States in the past 50 years, a new study suggests.

The findings, together with the evidence that niacin may induce glucose intolerance, insulin resistance and liver injury, imply the possibility that, among the fortified B-vitamins, excess niacin consumption may play a major role in the development of obesity and 2 diabetes.

Since the high level consumption of niacin in the US is mainly due to the implementation of mandatory grain fortification, therefore, it may be of significance to carefully evaluate the long-term safety of food fortification, the study concludes.

1. Zhou S-S, Li D, Zhou Y-M, et al. B-vitamin consumption and the prevalence of diabetes and obesity among the US adults: population based ecological study. BMC Public Health 2010; 10: 746. (open access)