Body Size and Serum 25 Hydroxy Vitamin D Response to Oral Supplements in Healthy Older Adults - RCT 2008
Miriam Blum, MD, Gerard E. Dallal, PhD, and Bess Dawson-Hughes, MD
Bone Metabolism Laboratory (M.B., B.D.H.) and Biostatistics Department (G.E.D.), Jean Mayer U. S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
Background: Vitamin D insufficiency is prevalent in the northeast United States. Since vitamin D insufficiency is readily amenable to supplementation, it is important to understand what factors are associated with serum 25 hydroxy vitamin D (25(OH)D) response to vitamin D supplementation.
Objective: In this study we examined the association of serum 25(OH)D response to vitamin D supplementation with body size in a population of elderly subjects.
Methods: 257 healthy, ambulatory men and women 65 years of age or older were randomly assigned to treatment with either 700 IU/day (17.5 /ng/d) of supplemental vitamin D3 and 500 mg/day (12.5 mmol/d) of supplemental calcium, or to placebo.
Results: In multivariate regression analyses, after adjusting for baseline 25(OH)D, season, and sex, we found change in 25(OH)D to be inversely associated with baseline BMI (p = 0.01) in subjects treated with supplements for one year. Change in 25(OH)D was also negatively associated with other baseline anthropometric measurements in these subjects.
Conclusion: Our study implies that body size should be taken into account when estimating the amount of vitamin D intake needed to raise 25(OH)D to the desired level.
Mean adjusted change in 25(OH)D level (±SEM) at one year in the calcium-vitamin D and placebo groups, each divided into subgroups based on BMI at baseline.
- SubgroupI: BMI < 25 kg/m2,
- subgroup II: 25 kg/m2 < BMI < 30 kg/m2,
- subgroup III: BMI 2=30 kg/m2).
Mean change in 25(OH)D level for calcium-vitamin D BMI subgroups (ANOVA P = 0.05) and placebo BMI subgroups (NS) are each adjusted for baseline 25(OH)D level and season. Sample size for the six groups from left to right are as follows: n = 47, n = 46, n = 59, n = 56, n = 26, n = 23. *Significantly differs from BMI subgroup I (P < 0.05). To convert values for serum 25(OH)D to nmol/l, multiply by 2.5.
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Obese response to 700 IU Vitamin D daily + Calcium is approximately 12 months - Feb 2025
__Obesity may extend the time required to reach a steady-state 25(OH)D level after initiating vitamin D supplementation - Feb 2025
JBMR Plus. 2025 Feb 8;9(4):ziaf030. doi: 10.1093/jbmrpl/ziaf030
Bess Dawson-Hughes 1, Elsa M Konieczynski 1, Lisa Ceglia 1 2
Obesity is known to influence the circulating 25(OH)D level but less is known about whether it influences the time required to reach a stable 25(OH)D level after initiating vitamin D supplementation. This observational study was done to investigate whether BMI modified the time required to reach a steady-state 25(OH)D level in response to vitamin D supplementation. Participants in the Boston STOP IT study who were treated for 12 mo with 700 IU of vitamin D3 and 500 mg of calcium daily and had 25(OH)D measures at 0, 6, and 12 mo, were included. We assessed the trajectory of 25(OH)D levels by baseline BMI category (normal weight, BMI 18.5-24.9 kg/m2, n = 62; overweight and obese, BMI ≥ 25 kg/m2, n = 105). Baseline 25(OH)D levels were 78 ± 31.3 nmol/L (normal weight) and 74.7 ± 36.5 nmol/L (overweight and obese). In a linear mixed model examining the influence of time and baseline BMI category on change in the mean 25(OH)D level, there was a significant time x BMI group interaction (p = .024. The normal weight participants had reached steady-state 25(OH)D levels by 6 mo whereas 25(OH)D levels continued to rise between 6 and 12 mo in the overweight and obese participants. This analysis suggests that the time required to reach a steady-state 25(OH)D level after initiating vitamin D supplementation in overweight and obese adults is greater than the usual 3-mo time point commonly used in clinical practice. A more refined definition of the time course of circulating 25(OH)D response to supplementation is needed in overweight and obese individuals in order to optimize clinical monitoring of vitamin D status.
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See also VitaminDWiki
- Overview Vitamin D Dose-Response
- Response to Vitamin D - many studies
- Obese responded to weekly vitamin D better than non-obese – RCT March 2018
- Response to Vitamin D sometimes takes a year
- 4,000 IU of Vitamin D daily is safe, but takes a year to plateau (Best-D) – RCT Dec 2016 2,000 IU 1 year