EFFECT OF MAGNESIUM-DEFICIENCY ON VITAMIN-B-2 AND VITAMIN-B-6 STATUS IN THE RAT

Objective: The present study was undertaken to investigate the effect of dietary magnesium (Mg) deficiency on vitamin B-2 (riboflavin) and B -6 (pyridoxine) status in rats. Methods: We fed Wistar rats an Mg-defi cient diet (56 mg magnesium per kg food) for 70 days, On days 21, 35 a nd 70 we measured Mg and manganese (Mn) in plasma and whole blood, alk aline phosphatase in plasma, erythrocyte glutathione reductase activit y coefficient (AC-EGR) for riboflavin status, and erythrocyte aspartas e transaminase activity coefficient (AC-EAST) for vitamin B-6 status. Results: Intake of the Mg-deficient diet significantly decreased plasm a and whole blood levels of Mg and plasma alkaline phosphatase activit y on all sampling days. The Mg deficit had no effect on plasma concent rations of Mn, but significantly increased whole blood levels of this element on days 35 and 70. The Mg-deficient diet had no effect on AC-E GR, and thus appeared not to affect riboflavin status. However, AC-EAS T was significantly increased on day 70, implying that the animals wer e at risk for vitamin B-6 deficiency. Conclusion: Mg deficiency impair s vitamin B-6 status by depleting intracellular Mg and thus inhibits t he activity of alkaline phosphatase, a metalloenzyme required for the uptake of pyridoxal phosphate by tissues. Although part of the intraer ythrocyte loss of Mg is countervailed by Mn, which can act as a substi tute activator of alkaline phosphatase, the degree of compensation is insufficient to fully offset the decrease in activity caused by Mg dep letion.