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Obese need 2X as much vitamin D to get the same response – June 2012

The Effect of Weight on Vitamin D Dose Response

Endocr Rev, Vol. 33 (03_MeetingAbstracts): OR38-3
Copyright © 2012 by The Endocrine Society ENDO 2012: June 23-26, 2012, Houston, Texas
Andjela T Drincic, MD1, Eileen Van Diest, MD2, Laura AG Armas, MD2, Robert P Heaney, MD2 and Susan Dowell, PhD2
1 Internal Medicine/Endocrinology, Universiy of Nebraska Medical Center Omaha, NE
2 Internal Medicine/Endocrinology, Creighton University Omaha, NE

Background: Obesity is associated with low 25(OH) vitamin D levels. Recent Endocrine Society Guidelines advise that obese adults need at least 6,000-10,000 IU/d of vitamin D3 to treat and prevent vitamin D deficiency. There are vitamin D dose response studies in normal to overweight populations (1), but none in the frankly obese.

Trial Design: The aim of this randomized, single-blind, study was to characterize the dose response of 25(OH)D to 3 different doses of vitamin D3 in a group of obese women and men.

Subjects, enrolled during the winter months, were randomly assigned to either 1,000 IU/d, 5,000 IU/d, or 10,000 IU/d of vitamin D3 for 21 weeks. At baseline, 25(OH)D, PTH, calcium, and serum creatinine were measured. Body composition by DXA and skin tone by IMS Smart Probe were also measured. During follow up visits at 1, 3, 6 and 10 weeks, 25(OH)D and calcium were measured. At week 21, serum 25(OH)D, PTH, serum calcium and 2 hour urine calcium and creatinine were obtained.

Inclusion/Exclusion Criteria: Healthy women and men with limited sun exposure, ages 19 – 70 years, BMI 30.0 kg/m2, low (<1,000 IU/d) intake of vitamin D3, no history of hepatic, renal disease, malabsorptive condition or medications that affect vitamin D metabolism.Results: 62 subjects of Caucasian or Hispanic origin (25 men and 37 women) were enrolled during winter months over two consecutive years (2009 and 2010). Average age was 45.8 years (SD12.5), average BMI 36.9 kg/m2 (SD 5.7).

Baseline 25(OH)D levels were as follows: 20.3 ng/ml in the 1,000 IU/d group, 25.7 ng/ml in the 5,000 IU/d group, and 23.2 ng/ml in the 10,000 IU/d group. Mean increments in 25(OH)D increase were as follows: 12.4 (SD 9.7) ng/ml in the 1,000 IU/d group, 27.8 (SD 10.2) ng/mL in the 5,000 IU/d group, and 48.1(SD 19.6) ng/ml in the 10,000 IU/d group. Compliance with therapy was 97.6 %. There were no adverse events during the study.

Conclusion: In obese subjects receiving 5,000 IU/d and 10,000 IU/d of vitamin D3 daily, the 25(OH)D rate of rise was approximately 0.5 ng/ml per 100 IU of vitamin D3 a day compared to reports of 1 ng/ml per 100 IU of vitamin D/d in normal weight people.
Obese people need approximately twice the daily dose of vitamin D3 as normal weight people to attain the same increment of 25(OH)D.
Everyone in the group that received 5,000 IU dose reached a 25(OH)D level > 30 ng/ml.

(1)Heaney RP et al., Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr 2003;77:204-210.

Nothing to Disclose: ATD, EVD, LAGA, RPH, SD

See also VitaminDWiki