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Urine samples before dinner are preferable when studying changes in endogenous nitrate production under uncontrolled dietary conditions.

J Egberts·W Soederhuizen
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Abstract

Changes in nitric oxide production result in changes in nitrate excretion, but these are difficult to detect if the daily intake of nitrate varies substantially. Instead of using a sample of the combined urine produced in 24 h for analysis, we studied the urine nitrate concentration in urine discharge at various times of the day. This was done with urine samples from each of seven men after a high dietary nitrate intake, followed by a low dietary intake 24 h later. The lowest variability in nitrate concentration was found in the samples before dinner (late afternoon) (511 +/- 201 (S.D.) mumol/l). However, the pre-dinner samples after a day with a nitrate-rich meal had still a 40% increased nitrate concentration (623 +/- 147 mumol/l), when compared with samples before the high nitrate diet (440 +/- 90 mumol/l; P < 0.05). This effect disappeared on the second day after the high nitrate meal (476 +/- 108 mumol/l). Similar results were found when using the nitrate/creatinine ratio. We conclude that urine samples taken before nitrate rich meals are the most reliable samples for estimating (changes in) endogenous nitrate production.

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AdultCreatinineDietEatingHumansMaleMiddle AgedNitratesReference ValuesTime FactorsJournal Article

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J Egberts, W Soederhuizen. 1996-10-29. Urine samples before dinner are preferable when studying changes in endogenous nitrate production under uncontrolled dietary conditions.. https://doi.org/10.1016/0009-8981(96)06380-2

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