DOES INCREASED NITRATE INGESTION ELEVATE NITRATE LEVELS IN HUMAN-MILK

Objective: To determine whether the nitrate content of human milk is i nfluenced by maternal ingestion of water containing elevated nitrate l evels. Design: Prospective, nonrandomized, volunteer study. Setting: C linical Research Center at the University of Iowa Hospitals and Clinic s, Iowa City. Patients: Twenty healthy lactating women with infants ol der than 6 months. Interventions: The mothers were asked to consume a minimum of 1500 mt of water containing 0 mg of nitrate per liter on da y 1, 45 mg on day 2, and 100 mg on day 3 in addition to consuming and recording their dietary intake. Breast-feeding was permitted during da ys 1 and 2, but milk was expressed on day 3 and the infants were given alternate food sources. After each 24-hour study day, maternal urine and milk samples were collected and frozen. A modified cadmium column reduction method was used to determine spot urinary and milk nitrate c ontent. Results: The mean total nitrate intake from diet and water on days 1, 2, and 3, respectively, was 46.6, 168.1, and 272.0 mg. Spot ur ine nitrate content on days 1, 2, and 3, respectively, was 36.0, 66.0, and 84.0 mg. Nitrate concentration of human milk on days 1, 2, and 3, respectively, was 4.4, 5.1, and 5.2 mg/L. Conclusion: Women who consu me water with a nitrate concentration of 100 mg/L or less do not produ ce milk with elevated nitrate levels.