Chronic niacin overload may be involved in the increased prevalence of obesity in US children.

Aim: To investigate nicotinamide's action on glucose metabolism, and the association between niacin consumption and obesity prevalence.

Methods: Dynamic nicotinamide's effect on plasma hydrogen peroxide and glucose metabolism was investigated using oral glucose tolerance tests with or without nicotinamide in the same five healthy subjects. Lag-regression analysis was used to examine the association between the niacin consumption and the obesity prevalence among US children using the data from the Economic Research Service of the US Department of Agriculture and from US Centers for Disease Control and Prevention, respectively.

Results: Compared with the control oral glucose tolerance test, the 1-h plasma hydrogen peroxide (1.4 +/- 0.1 micromol/L vs 1.6 +/- 0.1 micromol/L, P = 0.016) and insulin levels (247.1 +/- 129.0 pmol/L vs 452.6 +/- 181.8 pmol/L, P = 0.028) were significantly higher, and the 3-h blood glucose was significantly lower (5.8 +/- 1.2 mmol/L vs 4.5 +/- 1.1 mmol/L, P = 0.002) after co-administration of glucose and 300 mg nicotinamide. The obesity prevalence among American children increased with the increasing per capita niacin consumption, the increasing grain contribution to niacin due to niacin-fortification, and the increasing niacin-fortified ready-to-eat cereal consumption, with a 10-year lag. The regression analyses showed that the obesity prevalence in the US children of all age groups was determined by niacin consumption (R(2) = 0.814, 0.961 and 0.94 for 2-5 years, 6-11 years and 12-19 years age groups, respectively).

Conclusion: The appetite-stimulating effect of nicotinamide appears to involve oxidative stress. Excess niacin consumption may be a major factor in the increased obesity prevalence in US children.