Omeprazole and dietary nitrate independently affect levels of vitamin C and nitrite in gastric juice

TY - JOUR

T1 - Omeprazole and dietary nitrate independently affect levels of vitamin C and nitrite in gastric juice

AU - Mowat, Craig

AU - Carswell, Andrew

AU - Wirz, Angela

AU - McColl, Kenneth E.L.

PY - 1999/4

Y1 - 1999/4

N2 - Background and Aims: Hypochlorhydria is associated with an increased risk of gastric cancer. We have studied the effect of pharmacologically induced hypochlorhydria on the gastric juice ascorbate/nitrite ratio, which regulates the synthesis of potentially carcinogenic N-nitroso compounds. Methods: Saliva, gastric juice, and serum from 20 healthy volunteers (9 positive for Helicobacter pylori), with a mean age of 30 years (range, 20-47 years), were analyzed for nitrite, ascorbic acid, and total vitamin C before and for 2 hours after ingestion of 20 mmol nitrate (nitrate content of a standard salad meal). This was repeated after 4 weeks of treatment with omeprazole, 40 mg daily. Results: Before omeprazole treatment, the nitrate meal lowered gastric ascorbic acid levels from 3.8 to 0.9 μg/mL (P < 0.05) and increased median salivary nitrite levels from 44 to 262 μmol/L (P < 0.001); gastric nitrite concentration remained undetected in 10 subjects. Omeprazole increased median fasting gastric nitrite levels from 0 to 13 μmol/L (P = 0.001) and decreased fasting gastric ascorbic acid levels from 3.8 to 0.7 μg/mL (P < 0.001). With omeprazole treatment, gastric nitrite levels after the nitrate meal were markedly increased at 154 μmol/L (range, 49-384 μmol/L; P < 0.001). In H. pylori-infected subjects, omeprazole also decreased total vitamin C levels in both gastric juice and serum. Conclusions: Omeprazole and dietary nitrate independently decrease the ascorbate/nitrite ratio. This may lead to an increased risk of gastric cancer.

AB - Background and Aims: Hypochlorhydria is associated with an increased risk of gastric cancer. We have studied the effect of pharmacologically induced hypochlorhydria on the gastric juice ascorbate/nitrite ratio, which regulates the synthesis of potentially carcinogenic N-nitroso compounds. Methods: Saliva, gastric juice, and serum from 20 healthy volunteers (9 positive for Helicobacter pylori), with a mean age of 30 years (range, 20-47 years), were analyzed for nitrite, ascorbic acid, and total vitamin C before and for 2 hours after ingestion of 20 mmol nitrate (nitrate content of a standard salad meal). This was repeated after 4 weeks of treatment with omeprazole, 40 mg daily. Results: Before omeprazole treatment, the nitrate meal lowered gastric ascorbic acid levels from 3.8 to 0.9 μg/mL (P < 0.05) and increased median salivary nitrite levels from 44 to 262 μmol/L (P < 0.001); gastric nitrite concentration remained undetected in 10 subjects. Omeprazole increased median fasting gastric nitrite levels from 0 to 13 μmol/L (P = 0.001) and decreased fasting gastric ascorbic acid levels from 3.8 to 0.7 μg/mL (P < 0.001). With omeprazole treatment, gastric nitrite levels after the nitrate meal were markedly increased at 154 μmol/L (range, 49-384 μmol/L; P < 0.001). In H. pylori-infected subjects, omeprazole also decreased total vitamin C levels in both gastric juice and serum. Conclusions: Omeprazole and dietary nitrate independently decrease the ascorbate/nitrite ratio. This may lead to an increased risk of gastric cancer.

UR - https://www.scopus.com/pages/publications/0032999451

U2 - 10.1016/S0016-5085(99)70064-8

DO - 10.1016/S0016-5085(99)70064-8

M3 - Article

C2 - 10092303

AN - SCOPUS:0032999451

SN - 0016-5085

VL - 116

SP - 813

EP - 822

JO - Gastroenterology

JF - Gastroenterology

IS - 4

ER -