THE EFFICACY OF THREE DIFFERENT VITAMIN D SUPPLEMENTATION PROTOCOLS AFTER THE ROUX-EN-Y GASTRIC BYPASS PROCEDURE

The purpose of this research was to test how effective three vitamin D supplementation doses were after Roux-en-Y gastric bypass surgery. The Roux-en-Y gastric bypass procedure for obesity causes weight loss by restricting the amount of food an individual can consume and by decreasing the absorption of food in the small intestine. Twenty-five hydroxyvitamin D [(25(OH)D] is the measure of vitamin D in the blood. The effectiveness of supplementation was defined as increase in serum 25(OH)D per each 40 IU oral supplementation and number of subjects achieving optimal serum 25(OH)D (≥80 nmol/L) at twelve-months after surgery. Between November 2006 and December 2007, 47 subjects having surgery, aged 21 to 62 years, enrolled in the study. Subjects with serum 25(OH)D levels ≥50 nmol/L before surgery received 1200 IU vitamin D3 daily. Subjects with deficient vitamin D levels (<50 nmol/L) received 50,000 IU vitamin D2 weekly or 2800 IU vitamin D3 daily after surgery. In addition, 1200 IU D3/day were provided from a multivitamin/mineral and calcium supplements. The change in serum 25(OH)D from before surgery to twelve-months after surgery was investigated. The average 25(OH)D level for the non-deficient subjects (n=30) was 71.0 ± 15.6 nmol/L. The average 25(OH)D level for the low or deficient subjects (n=17), was 40.1 ± 15.6 nmol/L before surgery. Twelve-months after surgery, 72% of subjects taking 50,000 IU D2 weekly had optimal vitamin D status. Fifty percent of subjects taking 2800 IU D3 daily and 50% of the subjects taking 1200 IU D3 daily had optimal vitamin D levels. There was no difference in the effectiveness of weekly vitamin D2 supplementation versus daily vitamin D3 supplementation. Both types of vitamin D can be used for vitamin D supplementation. All three supplementation protocols were less effective at raising 25(OH)D levels than expected. During vitamin D repletion after Roux-en-Y gastric bypass surgery, serum 25(OH)D levels should be monitored and vitamin D doses adjusted.