Abstract
BackgroundThere is uncertainty as to which intake of vitamin D is needed to suppress PTH and maintain normal bone metabolism throughout winter at northern latitudes. We aimed to investigate whether four weeks’ daily supplementation with 10 μg vitamin D3 from fish oil produced a greater change in serum vitamin D metabolites, parathyroid hormone, and bone turnover in healthy adults compared with solid multivitamin tablets. Furthermore, it was studied whether age, gender, ethnic background, body mass index, or serum concentrations at baseline predicted the magnitude of change in these parameters.MethodsHealthy adults aged 19–48 years living in Oslo, Norway (59°N) were randomised to receive a daily dose of 10 μg vitamin D3 given as fish oil capsules or multivitamin tablets during four weeks in late winter. Serum samples from baseline and after 28 days were analysed for 25-hydroxyvitamin D (s-25(OH)D), 1,25-dihydroxyvitamin D (s-1,25(OH)2D), intact parathyroid hormone (s-iPTH), and osteoclast-specific tartrate-resistant acid phosphatase 5b (s-TRACP). Fifty-five eligible participants completed the intervention (74% of those randomised).ResultsS-25(OH)D increased by mean 34.1 (SD 13.1) nmol/l, p < 0.001; s-iPTH decreased by mean 1.2 (SD 2.5) pmol/l, p = 0.001; s-1,25(OH)2D increased by mean 13 (SD 48) pmol/l, p = 0.057; and s-TRACP increased by mean 0.38 (SD 0.33) U/l, p < 0.001. For all these parameters, there was no difference between fish oil and multivitamin formulation. Baseline concentrations were the only independent predictors of changes in biochemical parameters.ConclusionsFour weeks of daily supplementation with 10 μg vitamin D3 decreased mean s-iPTH and increased s-TRACP concentration, and this did not differ by mode of administration. Our results suggest an increased bone resorption following vitamin D supplementation in young individuals, despite a decrease in parathyroid hormone levels.Trial RegistrationClinicalTrials.gov: NCT01482689
Highlights
There is uncertainty as to which intake of vitamin D is needed to suppress parathyroid hormone levels (PTH) and maintain normal bone metabolism throughout winter at northern latitudes
Low vitamin D status is commonly observed at northern latitudes such as in Scandinavia during wintertime, with a drop in serum concentrations of 25-hydroxyvitamin D (s-25(OH)D) and a corresponding increase in serum parathyroid hormone levels (PTH) and bone turnover [1,2]
In our experimental study performed in Oslo (59°N) during late winter, we found a similar effect of fish oil capsules and multivitamin D tablets on increase in s-25 (OH)D [14]
Summary
There is uncertainty as to which intake of vitamin D is needed to suppress PTH and maintain normal bone metabolism throughout winter at northern latitudes. We aimed to investigate whether four weeks’ daily supplementation with 10 μg vitamin D3 from fish oil produced a greater change in serum vitamin D metabolites, parathyroid hormone, and bone turnover in healthy adults compared with solid multivitamin tablets It was studied whether age, gender, ethnic background, body mass index, or serum concentrations at baseline predicted the magnitude of change in these parameters. Healthy young students in Coleraine, Northern Ireland (55°N) who received a daily oral supplement of 15 μg (600 IU) vitamin D3 for 8 weeks in late winter, increased their mean s-25(OH)D from 47.9 to 86.5 nmol/l, but the supplementation did not influence PTH levels or bone turnover significantly [11]. Osteoporotic women in sunshine abundant São Paulo, Brazil (23°S) who received 10 μg (400 IU) vitamin D3 daily for three months increased their mean s-25(OH)D from 46.7 to 59.5 nmol/l, whereas PTH levels or bone turnover were not significantly affected [13]
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