We performed weekly analyses of the evolution of the bio-availability
of the Mg cation over a period of 70 days in adult rats fed an Mg-defi
cient (0.02%) diet. The results generally showed an increase in digest
ive utilization (% absorption) and a decrease in Mg balance during the
experimental period. The parameters most sensitive to Mg deficiency w
ere increase in body weight and blood concentration of Mg (mg/100 ml),
which had declined significantly after 7 days (p < 0.05). Significant
declines in plasma (p < 0.02) and muscle Mg (p < 0.01) were not appar
ent until after 35 days. Magnesium content in bone decreased from day
49 onward (p < 0.05), whereas renal Mg concentration tended to rise sl
ightly during the last 2 weeks of study. No change was found in brain
Mg concentration.