Nitrogen and mineral excretion after carbohydrate test meals

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Abstract
Four married couples were given a controlled diet for 5 days, and on the 6th, following an overnight fast, a 1-hr fasting urine sample was collected. The subjects were then given a test meal containing 6 g protein, 15 g fat, and 50 g carbohydrate with 82% supplied as glucose, fructose, sucrose, cornstarch, or wheat starch. Subsequently, urine samples were collected for five 1-hr periods, and analyzed for total nitrogen, urea, ammonia, creatinine, and uric acid nitrogen, as well as for sodium, potassium, phosphorus, and magnesium. Analysis of variance showed no significant F values for effect of different carbohydrates on the mean hourly excretion values for the 5-hr periods. At the 3rd hr, however, after the test meal containing fructose, there was an increase over the fasting value in uric acid nitrogen per milligram creatinine nitrogen that met the 5% level of significance and approached significance after the test meal with sucrose. The increases were greater for the women than for the men. Magnesium excretion at the 1st and 2nd hr after the test meal containing fructose was consumed was significantly higher than the fasting value and approached significance after sucrose with only small differences after glucose or the two starches. There were significant differences between the men and women in hourly changes in excretion of phosphorus and magnesium after the test meals.