Vitamin B6 and magnesium.

Administration of vitamin B6 at doses of 1 and 1.5 g/day, for 2-7 weeks, showed that only the high doses increased erythrocyte magnesium. Similarly, magnesium balance studies in subjects receiving 500, 1,000 and 1,500 mg/day of vitamin B6 for 8 days showed that doses of 1 g or less had no effect upon the intestinal absorption of magnesium. In view of the existence of reversible neurological complications in subjects taking 2 g of pyridoxine per day, the use of very high doses of vitamin B6 must be considered as inadvisable, even if effective. A study of the long-term effects, and upon leukocyte magnesium, of doses of 1 g or less would be desirable.