Nitrite and nitrate levels in ileostomy effluent: effect of dietary change.

1. Nitrite and nitrate levels were measured in samples from ileostomy bags or stomal samples of thirty-one ileostomists (twenty-two ulcerative colitis, nine Crohn's disease), 14-16 h after ingestion of a conventional meal or a meal containing a high content of nitrite and nitrate. 2. Ileostomy samples were decolourized with barium chloride, sodium sulphate and charcoal. Nitrite was determined spectrophotometrically by the Griess reaction and nitrate determined as nitrite after reduction with nitrate reductase (EC 1.7.99.4) in the presence of sodium formate. The mean percentage recovery from twenty-six spiked samples was 101.9 (SE 3.5)% for nitrite and 82.9 (SE 3.3)% for nitrate. 3. Ileostomy bag samples were obtained in twenty-nine cases of which ten had measurable nitrite (median 0, range 0-20.7 nmol/g) on a conventional meal compared with twenty-three cases (median 7.2, range 0-31.1 nmol/g) on the test meal (P less than 0.01). Nitrate levels were measurable in sixteen (median 6.7, range 0-48.2 nmol/g) after a conventional meal compared with twenty-one (median 20.5, range 0-53.2 nmol/g) after the test meal (P less than 0.01). 4. Stomal fresh-catch samples were obtained in twenty-four cases: combined nitrate and nitrite was higher in eighteen, lower in four and unchanged in two subjects after the test meal (P less than 0.05). 5. The type of foodstuff ingested can significantly alter measurable levels of nitrite-nitrate in the distal ileum and is one factor determining nitrite-nitrate input into the proximal colon.