| Description |
Magnesium (Mg) is an essential mineral that is important for bone health, energy production, and vasodilation; however, in the American diet, Mg intake is consistently below the Recommended Dietary Allowance (RDA). The aims of this project were to 1) assess which dietary form of Mg has the greatest bioavailability, 2) determine the effects of Mg depletion upon metabolic rate and energy expenditure, and 3) determine if Mg depletion alters vascular function. Sixty-four male C57BLK/6J mice were split into 4 groups for tissue concentration studies. One group consumed a diet containing a concentration of 100mg/kg Mg Oxide (n=22) for 3 weeks to produce Mg depletion. The other groups followed the same 3 week Mg depletion protocol (100mg/kg Mg Oxide), but then were given either 500mg/kg Mg Citrate (n=10), 500mg/kg Mg Malate (n=10), or 500mg/kg Mg Bisglycinate (n=22) for 1 week to replete Mg status. Mg Citrate and Mg Bisglycinate restored heart tissue Mg to equivalent concentrations while Mg Malate actually reduced heart Mg tissue concentration by 64% (p<.001). Mg Citrate restored bone Mg by 19% (p=.018), which was the greatest restoration. Liver Mg levels remained unchanged on all diets. Muscle Mg remained the same after replenishment with Mg Bisglycinate and was reduced by 62% on Mg Citrate (p<.001) and by 35% on Mg Malate (p<.001). A subset of 24 mice were used to address aims 2 and 3, and received 100mg/kg Mg Oxide diet for 3 weeks, or 100mg/kg Mg Oxide followed by repletion with 1 week on a 500mg/kg Mg Bisglycinate diet. Body fat was reduced by 35% in mice with 500mg/kg Mg Bisglycinate (p=.005). Activity levels trended higher (p=.085), energy expenditure was higher (p=.001), and respiration rates were higher (p=.003) after repletion with 500mg/kg Mg Bisglycinate. Function of the vasculature was unchanged after repletion with 500mg/kg Mg Bisglycinate. In conclusion, these results indicate that Mg Citrate and Mg Bisglycinate are more effective at restoring tissue mg levels than Mg Malate. Further, low Mg intake may induce unfavorable body composition changes and reduce energy expenditure, but does not affect vascular function. |
