Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/1998
Publication Date: N/A
Technical Abstract: In five separate experiments in which the primary dietary variable was magnesium (Mg) intake, calcium (Ca) balances were determined in a total of 73 postmenopausal women living on a metabolic ward. Mean basal dietary Mg among treatment groups varied from 104 to 159 mg/day, which generally resulted in non-positive Mg balance. Magnesium was replenished with a supplement of 200 mg Mg/day as Mg gluconate. Dietary composition was similar among the experiments except for noticeable (more than two-fold) differences (range in mg/2000 kcal) in copper (Cu; 1-3), manganese (0.9- 2.8), ascorbic acid (93-204), and folacin (180-467). Fructose as per cent of calories varied in four experiments from 2.3 to 4.6; it was 15.6 in the fifth. In three experiments, Ca balances were generally positive with mean Ca intakes for each treatment period ranging from 657 to 768 mg/day (analyzed). In the other two experiments, mean Ca balances were non- positive with mean Ca intakes ranging from 728 to 873 mg/day; the greatest differences in Mg balances attributable to Mg intakes occurred in these experiments. The most negative Ca balances were found when dietary fructose was 15.6% of energy. Also, with high dietary fructose, the effect of dietary Mg on Ca balance seemed to be influenced by dietary Cu; the most negative balance (-48 mg/day) occurred in women who consumed diets low in Cu (1 mg/day) and Mg (114 mg/day). Low Mg intakes (104-122 mg/day) increased Ca balance when dietary fructose was low. The findings suggest that Ca balance can be maintained in postmenopausal women with intakes less than 800 mg/day, but can be altered by undesirable changes in dietary Mg, fructose and copper.