Vitamin D status following bariatric surgery: implications and recommendations.

Individuals with extreme obesity who qualify for bariatric surgery are frequently vitamin D deficient before and after surgery. The anatomical changes that occur during some bariatric procedures may lead to decreased absorption of vitamin D, although vitamin D absorption and metabolism has not been quantified or compared across surgeries, and multiple other factors could influence vitamin D status in these individuals. Vitamin D treatment and dosing studies show that there is variability in how individuals respond to supplementation regimens regardless of the bariatric procedure. It is unknown if improving vitamin D status before and/or after bariatric surgery can affect health-related outcomes in this population beyond the traditional roles of vitamin D. Vitamin D has been purported to positively influence a variety of obesity-related comorbidities. Furthermore, in light of the potential role of vitamin D in immunity and inflammation, it seems important to consider the ramifications of vitamin D deficiency in the postbariatric individual in the critical care setting and particularly in the context of aging. Additional research is needed to develop evidence-based guidelines for optimal treatment of vitamin D deficiency in individuals before and after bariatric surgery and to determine the impact of vitamin D repletion on non-bone health-related outcomes in these individuals.

Serum 25(OH) vitamin D concentration changes after Roux-en-Y gastric bypass surgery.

OBJECTIVE: To describe serum 25(OH)D changes after Roux-en-Y gastric bypass (RYGB) and to determine if fat mass (FM) loss and vitamin D intake are associated with changes in serum levels. DESIGN AND METHODS: The relationship between serum 25(OH)D and 1) FM, 2) weight, 3) % excess weight loss (EWL), and 4) BMI was investigated after controlling for potential confounders using a mixed effects linear model in 20 women before and up to 1-year post-RYGB. Subcutaneous (SAT) and visceral adipose tissue (VAT) vitamin D concentrations at time of RYGB were also evaluated. RESULTS: Weight and FM decreased 1-year after surgery by 45 ± 1 kg and 37 ± 1 kg, respectively while 25(OH)D increased by 10 ± 2 ng mL(-1) . Weight, FM, BMI, and %EWL changes were associated with 25(OH)D change. VAT had an average 21% more vitamin D per gram than SAT and concentrations were highly correlated. CONCLUSIONS: Although weight loss may lead to increased serum 25(OH)D after RYGB, low levels remain a concern in some patients 1-year postsurgery. Additional research is needed to clarify the relationship between adipose storage of vitamin D and serum 25(OH)D in obesity, and how that relationship might change after surgery. This could lead to improved clinical management of vitamin D in this ever-growing clinical population.