Vitamin D and intestinal calcium transport after bariatric surgery

Abstract

Bariatric surgery is a highly effective treatment for obesity, but it may have detrimental effects on the skeleton. Skeletal effects are multifactorial but mediated in part by nutrient malabsorption. While there is increasing interest in non-nutritional mechanisms such as changes in fat-derived and gut-derived hormones, nutritional factors are modifiable and thus represent potential opportunities to prevent and treat skeletal complications. This review begins with a discussion of normal intestinal calcium transport, including recent advances in our understanding of its regulation by vitamin D, and areas of continued uncertainty. Human and animal studies of vitamin D and intestinal calcium transport after bariatric surgery are then summarized. In humans, even with optimized 25-hydroxyvitamin D levels and recommended calcium intake, fractional calcium absorption decreased dramatically after Roux-en-Y gastric bypass (RYGB). In rats, intestinal calcium absorption was lower after RYGB than after sham surgery, despite elevated 1,25-dihyroxyvitamin D levels and intestinal gene expression evidence of vitamin D responsiveness. Such studies have the potential to shed new light on the physiology of vitamin D and intestinal calcium transport. Moreover, understanding the effects of bariatric surgery on these processes may improve the clinical care of bariatric surgery patients.

European Society of Endocrinology Clinical Practice Guideline: Endocrine work-up in obesity

“…The prevalence of sHPT was observed to increase up to 50% in patients 2 years after bariatric surgical interventions. In addition, in order to prevent or attenuate bone loss it is recommended to ensure that sufficient 25OHD levels are attained (171), bearing in mind that vitamin D supplements in higher dosages are required to overcome decreased absorption (183). However, the ideal vitamin D replacement therapy and target 25OHD concentrations in the obese or bariatric populations are unknown.…”

Bariatric Surgery for Adolescents with Type 2 Diabetes: an Emerging Therapeutic Strategy

“…Even in adolescents who have reached adult height, adolescence is a critical period for bone mineral accretion(99). The impairment of BMD following bariatric surgery in adolescents may be related to impaired intestinal calcium absorption, particularly after RYGB(100), although other, non-nutritional factors may play a role as well. For example, reduced body weight might diminish mechanical load-induced bone mineralization.…”

Saliva with reduced calcium and phosphorous concentrations: Effect on erosion dental lesions

“…Bariatric patients may have an increased risk of developing nutritional deficiencies, which occur due to vomiting, reduced food intake, intolerance to foods, reduction of gastric secretions, and the derivation of absorption areas (Gletsu‐Miller & Wright, ). From the micronutrients standpoint, calcium deficiency is among the nutritional abnormalities following bariatric surgery (Schafer, ). To complicate the matter, bariatric patients face intestinal calcium malabsorption due to hypovitaminosis D, another consequence of bariatric surgery (Peterson et al., ; Schafer, ).…”

“…From the micronutrients standpoint, calcium deficiency is among the nutritional abnormalities following bariatric surgery (Schafer, ). To complicate the matter, bariatric patients face intestinal calcium malabsorption due to hypovitaminosis D, another consequence of bariatric surgery (Peterson et al., ; Schafer, ). In spite of over 80% of the bariatric patients make use of nutritional supplements (Bloomberg, Fleishman, Nalle, Herron, & Kini, ), the prevalence of hypocalcemia among them is still as high as 25% (Newbury, Dolan, Hatzifotis, Low, & Fielding, ; Shah et al., ).…”

“…The degree of Ca/Pi saturation in saliva of patients submitted to bariatric surgery may be reduced not only by deficiency of serum calcium and vitamin D (Schafer, 2017) but also by phosphorous deficiency (Compher, Badellino, & Boullata, 2008). Considering that reductions of the biological levels of calcium phosphate in saliva saturation reduce mineral precipitation on eroded dental tissues (Hara, Karlinsey, & Zero, 2008), it can be estimated that rehardening of dental tissues after gastric acid exposure may be impaired.…”