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Gastric bypass reduces vitamin D by at least 25 percent – Feb 2011

Vitamin D Absorption: Consequences of Gastric Bypass Surgery.

Eur J Endocrinol. 2011 Feb 21.
Aarts E, van Groningen L, Horst R, Telting D, van Sorge A, Janssen I, de Boer H.
E Aarts, Surgery, Rijnstate Hospital, Arnhem, Netherlands.

Objective: To develop a test that quantifies the changes in intestinal cholecalciferol absorption induced by Roux-en-Y gastric bypass (RYGB) surgery.

Background: Severe vitamin D deficiency is a common finding in morbid obesity, and the incidence increases markedly after RYGB. Normalisation of vitamin D levels after RYGB is difficult to achieve because the degree of surgery-induced malabsorption is not known.

Methods: Absorption characteristics of cholecalciferol were studied in 14 morbidly obese, premenopausal women before and 4 weeks after laparoscopic RYGB. Serum cholecalciferol levels were measured at baseline, and 1, 2, 3 and 14 days after a single oral dose of 50.000 IU of solubilised cholecalciferol.

Results: Peak serum cholecalciferol levels were observed on day 1 in all patients. They were 26.6 ± 3.7% lower after RYGB (P = 0.02). Inter-individual variability was high.

Conclusion: Peak cholecalciferol levels are reduced by about 25% after RYGB. Further analysis suggested that the timing of sampling in the current study was not optimal. This may have caused an underestimation of the true decrease in cholecalciferol absorption induced by RYGB.
PMID: 21339336

See also VitaminDWiki