Magnesium status in healthy free-living elderly Norwegians.
OBJECTIVE
Magnesium (Mg) status has previously not been properly assessed among healthy elderly subjects.


METHODS
Thirty-six healthy elderly subjects participated. Their Mg status was assessed by serum Mg, basal urinary Mg output, and with a Mg loading test (30 mmol infused during 8 hours; urine sampled 24 hours), and compared with 53 healthy younger subjects. Their dietary intake was assessed by a quantified food frequency questionnaire. Fourteen of the subjects received 300 mmol Mg to study the effect on Mg status.


RESULTS
With the exception of vitamin D in women, average energy and nutrient intakes were adequate. All subjects had serum Mg levels within the reference value of the laboratory. Basal urinary Mg excretion was 3.3 +/- 1.1 mmol/day and 24-hour Mg retention after a Mg load was 28 +/- 16% compared to 6 +/- 11% in younger controls, suggesting Mg deficiency in the elderly. In the 14 subjects who received oral Mg supplementation there was a statistically significant increase in basal urinary Mg excretion and creatinine clearance, and decreases in Mg retention, serum Mg and serum creatinine.


CONCLUSIONS
This study suggests that a significant subclinical Mg deficit, not detected by serum Mg, was present in many of these healthy elderly subjects. Mg supplementation improved Mg status and renal function.
Gullestad
L
L
Department of Medicine B, National Hospital, Oslo, Norway.
Nes
M
M
Rønneberg
R
R
Midtvedt
K
K
Falch
D
D
Kjekshus
J
J
D000368:Aged; D000375:Aging; D004032:Diet; D005260:Female; D006801:Humans; D008274:Magnesium / Q000008:administration & dosage / Q000097:blood*; D008275:Magnesium Deficiency / Q000453:epidemiology; D008297:Male; D009664:Norway; D009752:Nutritional Status; D012016:Reference Values
D008274:Magnesium