Before surgery, we demonstrated a higher incidence of vitamin D deficiency in morbidly obese French patients as compared to the general population. The incidence was also higher than previous American studies. Screening for hypovitaminosis D may routinely be considered in morbid obesity. Long-term observation is, however, needed to assess the advantages and potential side effects of systematic vitamin D supplements.

No significant difference in 25(OH) vitamin D level could be demonstrated between obese patients before bariatric surgery and obese patients with no obesity surgery project. No difference was found between our Parisian obese population and a Spanish obese population, which benefits from a better solar exposure. Both findings suggest that obesity itself is the link with vitamin D deficiency, independently from behavioral differences.