Gastroenterology

Gastroenterology

Volume 116, Issue 4, April 1999, Pages 813-822
Gastroenterology

Alimentary Tract
Omeprazole and dietary nitrate independently affect levels of vitamin C and nitrite in gastric juice,☆☆

https://doi.org/10.1016/S0016-5085(99)70064-8Get rights and content

Abstract

Background & 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.

GASTROENTEROLOGY 1999;116:813-822

Section snippets

Subjects

Twenty-three healthy volunteers were studied (7 men and 16 women; mean age, 30 years; age range, 20–47 years). None had a history of gastrointestinal disease, and none had dyspepsia. H. pylori status was determined by a [14C]urea breath test, as previously described.39

Design

The study took place on 2 separate days. Subjects avoided eating leafy vegetables for 24 hours before presenting fasted on the morning of each study day. On day 1, basal samples of blood, saliva, and gastric juice were collected,

Results

Three subjects dropped out after the first study day and were excluded from the analysis. All values are expressed as medians with ranges in parentheses.

Discussion

This study indicates that pharmacologically induced profound hypochlorhydria depletes intragastric AA concentrations and increases intragastric nitrite concentrations. These changes are apparent in the fasting state but are even more marked after ingestion of nitrate. In H. pylori–positive subjects, pharmacologically induced hypochlorhydria also decreases both gastric and serum TVC concentrations.

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    Address requests for reprints to: Kenneth E. L. McColl, M.D., University Department of Medicine and Therapeutics, Western Infirmary, Glasgow G11 6NT, Scotland. e-mail: [email protected]; fax: (44) 141-339-2800.

    ☆☆

    Supported by the Scottish Home and Health Department, Scottish Office, Edinburgh, Scotland.

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