Acute dietary nitrate consumption improves glucose tolerance

Abstract

Insulin resistance is characterized by low nitric oxide (NO) bioavailability. Consistent with this observation, insulin sensitivity is improved with stimulation of NO generating pathways. Consumption of dietary nitrate (e.g. beet juice) has been purported to increase NO formation, mediated in part through the reduction of nitrate (NO3−) to nitrite (NO2−) by oral bacteria, and subsequent NO2− reduction to NO in blood. We hypothesized that acute dietary nitrate consumption would improve glucose tolerance. Accordingly, in 8 sedentary adults (23 ± 0 years, body mass index: 26.0 ± 0.8 kg/m2 (mean ± SE)) we determined the blood glucose response to oral consumption of 500 ml organic beet juice, supplemented with 25 g of sucrose (estimated carbohydrate load ~ 75g), with and without prior use of an antibacterial mouthwash to inhibit NO3− reduction to NO2−. In the absence of inhibition of oral bacteria NO3− reductase activity, peak blood glucose concentration (106 ± 4 vs. 118 ± 6 mg/dL; P = 0.04) and the area under the blood glucose response curve (93 ± 4%; P = 0.07) were decreased. These preliminary data suggest dietary nitrate consumption may promote glucose tolerance, and this effect may be attenuated following inhibition of NO3− conversion to NO2−.Support: America Diabetes Association 1‐09‐RA‐09