Vitamin D Stored in Fat Tissue During a 5-Year Intervention Affects Serum 25-Hydroxyvitamin D Levels the Following Year

J Clin Endocrinol Metab. 2017 Oct 1;102(10):3731-3738. doi: 10.1210/jc.2017-01187.

Abstract

Context: Vitamin D and 25-hydroxyvitamin D [25(OH)D] are stored in adipose tissue, but the clinical relevance is uncertain.

Objective: To evaluate changes in serum 25(OH)D and adipose tissue vitamin D levels after stopping vitamin D supplementation.

Design: A prospective, double-blind cohort follow-up study.

Setting: Clinical Research Unit at University Hospital of North Norway.

Patients: Seventy-six subjects were included after participation in a 3- to 5-year prevention of type 2 diabetes study and were administered 20,000 IU of vitamin D or placebo per week.

Intervention: During the 12-month follow-up period, blood samples were drawn at the beginning and after 1, 3, 6, 9, and 12 months. Fat biopsies were taken at the start and end.

Main outcome measures: Changes in 25(OH)D level in serum and 25(OH)D and vitamin D levels in adipose tissue.

Results: Forty-one of 42 subjects who were given vitamin D and 33 of 34 subjects who were given placebo completed the study. At the inclusion, mean serum 25(OH)D levels were 122 and 71 nmol/L in the vitamin D and placebo groups, respectively. Serum 25(OH)D levels were significantly higher in the vitamin D group than in the placebo group throughout and were 84.5 and 73.1 nmol/L, respectively, after 12 months. In the vitamin D group, adipose tissue vitamin D levels decreased by 52% over 12 months.

Conclusion: Vitamin D and 25(OH)D stored in adipose tissue after 3 to 5 years of vitamin D supplementation may have a clinically relevant effect on serum 25(OH)D level the following year.

Trial registration: ClinicalTrials.gov NCT01729013.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adipose Tissue / metabolism*
  • Aged
  • Aged, 80 and over
  • Diabetes Mellitus, Type 2 / etiology
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / prevention & control
  • Dietary Supplements
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Placebos
  • Time Factors
  • Vitamin D / administration & dosage*
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D / metabolism*
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / diet therapy*
  • Vitamin D Deficiency / metabolism

Substances

  • Placebos
  • Vitamin D
  • 25-hydroxyvitamin D

Associated data

  • ClinicalTrials.gov/NCT01729013