Effects of acute and repeated oral doses of D-tagatose on plasma uric acidin normal and diabetic humans

D-Tagatose, a stereoisomer of D-fructose, is a naturally occurring ketohexo se proposed for use as a low-calorie bulk sweetener, Ingested D-tagatose ap pears to be poorly absorbed. The absorbed portion is metabolized in the liv er by a pathway similar to that of D-fructose. The main purpose of this stu dy was to determine if acute or repeated oral doses of D-tagatose would cau se elevations in plasma uric acid las is seen with fructose) in normal huma ns and Type 2 diabetics. In addition, effects of subchronic D-tagatose inge stion on fasting plasma phosphorus, magnesium, lipids, and glucose homeosta sis were studied. Eight normal subjects and eight subjects with Type 2 diab etes participated in this two-phase study, Each group was comprised of four males and four females, In the first phase, all subjects were given separa te 75 g 3-h oral glucose and D-tagatose tolerance tests. Uric acid, phospho rus, and magnesium were determined in blood samples collected from each sub ject at 0, 30, 60, 120, and 180 min after dose, In the 8-week phase of the study, the normals were randomly placed into two groups which received 75 g of either D-tagatose or sucrose (25 g with each meal) daily for 8 weeks. T he diabetics were randomized into two groups which received either 75 g D-t agatose or no supplements of sugar daily for 8 weeks. Uric acid, phosphorus , magnesium, lipids, glycosylated hemoglobin, glucose, and insulin were det ermined in fasting blood plasma of all subjects at baseline (time zero) and biweekly over the 8 weeks. The 8-week test did not demonstrate an increase in fasting plasma uric acid in response to the daily intake of D-tagatose. However, a transient increase of plasma uric acid levels was observed afte r single doses of 75 g of D-tagatose in the tolerance test, Plasma uric aci d levels were found to rise and peak at 60 min after such dosing. No clinic al relevance was attributed to this treatment-related effect because excurs ions of plasma uric acid levels above the normal range were small and were of short duration. Consistent with earlier observations on fructose, the in crease of plasma uric acid was associated with a slight decrease of plasma phosphorus and a slight increase of magnesium, The daily ingestion of D-tag atose for 8 weeks had no effect on fasting plasma magnesium, phosphorus, ch olesterol, triglycerides, glycosylated hemoglobin, glucose, and insulin lev els. The ingestion of three 25-g doses per day for a period of 8 weeks resu lted in varying amounts of flatulence in seven of the eight subjects, and s ome degree of diarrhea in six subjects. D-Tagatose holds promise as a sweet ener with no adverse clinical effects observed in these studies. (C) 1999 A cademic Press.