EFFECTS OF DIET ON MEASUREMENT OF NITRIC-OXIDE METABOLITES

1. The present study investigated whether a low nitrate/nitrite diet c ould minimize variability in the measurement of endogenous plasma and urine nitric oxide (NO) metabolites, nitrate and nitrite (NOx) in norm al subjects. 2. Nitrate and nitrite concentrations were measured in pl asma and urine as indicators of NO production in six subjects during a free diet and then during a low nitrate/nitrite diet for 6 days, 3. T he plasma concentration and 24 h urine NOx/creatinine ratio were signi ficantly lower on the low nitrate/nitrite diet than on the free diet ( P< 0.01), Nitric oxide production appeared to vary greatly within and between subjects, but these variations were substantially decreased by the fourth day of a low nitrate/nitrite diet. 4. Human plasma and uri ne NO, measurements should be determined after a low nitrate/nitrite d iet for at least 4 days.