Determination of Variances in Exhaled Nitric Oxide Output in Normal Healthy Male Volunteers Consuming High and Low Nitrate/Nitrite Diets

Study Summary

This study will determine whether and how nitrites and nitrates in the diet affect the level of nitric oxide gas that is breathed out in air. Nitric oxide is involved in many bodily processes, such as immune function, nerve signal transmission, inflammation, and dilation of blood vessels and bronchial tubes (tubes that branch out from the trachea into the lungs). Healthy male volunteers age 18 years or older who have not smoked for at least 5 years may be eligible for this study. Candidates will undergo blood and urine tests, breathing tests, and an electrocardiogram. Participants will follow two special diets for 3 days each. One is a low-nitrate and nitrite diet, and the other is a high-nitrate and nitrite diet. Both diets must be completed within a month's time. Participants will be admitted to the NIH Clinical Center for two 3-night hospital stays during the two diet periods, but may go out on passes at any time. While on the diets, they may consume only food prepared by the NIH Nutrition Department; eating other foods will seriously affect the study results. Meals may be eaten at the NIH Clinical Center, or packaged meals prepared by the Nutrition Department can be taken out. Participants may not engage in any heavy exercise during the diet periods, as exercise affects nitric oxide levels. Blood samples of about 4 milliliters, or 1 teaspoon, each will be collected before starting each diet and at the end of each diet to measure blood levels of nitrate and nitrite. Additional blood samples, totaling about 2 tablespoons, will be collected for research. Each day, participants will have a test to measure exhaled nitric oxide levels. This involves blowing air into a mouthpiece attached to a machine that measures levels of the gas in each breath.