Long-term dietary inorganic nitrate increases gastric mucosal blood flow in Mongolian gerbils

Inorganic nitrate is rich in human diet especially in some vegetables. Dietary inorganic nitrate can be absorbed into blood, reduced to nitrite by oral bacteria, and further reduced to nitric oxide (NO) in the acidic stomach, which exerts multiple physiological functions in the body. It was reported that short-term administration of dietary nitrate can increase gastric mucosal blood flow to maintain the gastric mucosal integrity. However, the effect of long-term dietary inorganic nitrate on gastric mucosal blood flow is unknown. Here we show that long-term delivery of dietary nitrate significantly increases gastric mucosal blood flow in Mongolian gerbils. Compared to the sodium chloride treated group, the nitrate treated group had significantly higher nitrate and nitrite levels in blood. Furthermore, the level of gastric mucosal prostaglandin E₂ (PGE₂), which is crucial in maintaining the cellular integrity via improving gastric blood flow, is significantly enhanced by long-term dietary nitrate. Also, histological analyses showed no abnormalities in the gastric mucosa after the long-term nitrate treatment. This study provides evidences that long-term nitrate supplementation in diet is beneficial for maintaining gastric mucosal blood flow. These findings suggest an important physiological role of nitrate in the diet.