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- Title
Effect of vitamin D supplementation on free and total vitamin D: A comparison of Asians and Caucasians.
- Authors
Gopal‐Kothandapani, Jaya Sujatha; Evans, Lucy Faith; Walsh, Jennifer S.; Gossiel, Fatma; Rigby, Alan S.; Eastell, Richard; Bishop, Nick J.
- Abstract
Summary: Objectives: It is well established that UK Asians typically have lower vitamin D levels than Caucasians. It is also known that vitamin D binding protein (DBP) is lower in some races than Caucasians. To investigate how ethnicity, skin colour and genetic variation affect the response to vitamin D (15000 IU) administered to young Asian and Caucasian men. Design: Prospective, single‐centre clinical trial. Participants: Sixty young men (18‐25 year) of Asian (n = 30) and Caucasian (n = 30) origin. Measurements: We measured serum calcium, phosphate, magnesium, alkaline phosphatase, albumin, parathyroid hormone; total 25 hydroxyvitamin D (25OHD); calculated and directly measured free 25OHD; DBP at baseline and 4 weeks; DBP genotype, skin colour (Fitzpatrick scale), dietary vitamin D and calcium intake at baseline; and urine calcium:creatinine ratio at baseline, 1 and 4 weeks. Results: At baseline, Asians had lower serum total 25OHD (26.4 [13.7] vs 34.1 [12.3] nmol/L P = 0.0272) and DBP (6.7 [3.4] vs 9.6 [4.4] nmol/L; P = 0.0065) but similar free 25OHD (16.7 [10.4] vs 17.8 [7.5] pmol/L P = 0.6530). After dosing, total 25OHD rose similarly in each group (≈56 nmol/L), but measured free 25OHD rose more in Asians (18.1 [9.4] vs 12.2 [13.3] pmol/L P = 0.0464). Lower DBP at baseline, possibly reflecting genotype differences, was associated with a greater change in measured free 25OHD in Caucasians, but not in Asians. Conclusions: Asian compared with Caucasian males had a larger increment in measured free 25OHD following 150 000 units vitamin D3, possibly reflecting differences in DBP affinity for 25OHD. Ethnicity should be considered when devising guidelines for the treatment of vitamin D deficiency.
- Subjects
VITAMIN D; CALCIUM regulating hormones; STEROID hormones; CALCITONIN; PARATHYROID hormone
- Publication
Clinical Endocrinology, 2019, Vol 90, Issue 1, p222
- ISSN
0300-0664
- Publication type
Article
- DOI
10.1111/cen.13825