|
Efficacy
and safety of vitamin D3 intake exceeding the lowest observed adverse effect
level
Vieth R, Chan PC, MacFarlane
GD
Mount Sinai Hospital, Toronto, Ontario,
Canada.
rvieth@mtsinai.on.ca
Background.
The Food and Nutrition Board of the National Academy of Sciences
states that 95 microg vitamin D/d is the lowest observed adverse effect level (LOAEL).
Objective.
Our objective was to assess the efficacy and safety of prolonged
vitamin D3 intakes of 25 and 100 microg (1000 and 4000 IU)/d.
Efficacy was based
on the lowest serum 25-hydroxyvitamin D [25(OH)D] concentration achieved by
subjects taking vitamin D3; potential toxicity was monitored by measuring serum
calcium concentrations and by calculating urinary calcium-creatinine ratios.
Design.
Healthy men and women (n = 61) aged 41 +/- 9 y (mean +/- SD) were
randomly assigned to receive either 25 or 100 microg vitamin D3/d for 2-5 mo,
starting between January and February.
Serum 25(OH)D was measured by
radioimmunoassay.
Results.
Baseline serum 25(OH)D was 40.7 +/- 15.4 nmol/L (mean
+/- SD).
From 3 mo on, serum 25(OH)D plateaued at 68.7 +/- 16.9 nmol/L in the
25-microg/d group and at 96.4 +/- 14.6 nmol/L in the 100-microg/d group.
Summertime serum 25(OH)D concentrations in 25 comparable subjects not taking
vitamin D3 were 46.7 +/- 17.8 nmol/L.
The minimum and maximum plateau serum
25(OH)D concentrations in subjects taking 25 and 100 microg vitamin D3/d were 40
and 100 nmol/L and 69 and 125 nmol/L, respectively.
Serum calcium and urinary
calcium excretion did not change significantly at either dosage during the
study.
Conclusions.
The 100-microg/d dosage of vitamin D3 effectively increased
25(OH)D to high-normal concentrations in practically all adults and serum
25(OH)D remained within the physiologic range; therefore, we consider 100 microg
vitamin D3/d to be a safe intake.
PMID: 11157326 [PubMed - indexed for MEDLINE]
|
