Vitamin D Status and Seasonal Variation: A Retrospective Single Institution Database Study of Patients Pursuing Metabolic/Bariatric Surgery

Hannah Hays, Laura E. Flores, Vishal Kothari, Laura Bilek, Jenenne Geske, Anne Skinner

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Background: Obesity is associated with suboptimal levels in vitamin D, a nutrient important for bone health and immune function. Seasonal variation in vitamin D may exacerbate this deficiency in persons with obesity, as exposure to ultraviolet B rays in sunlight is necessary for the conversion of vitamin D to its active form in the body. The aim of this study was to determine the relationship between season and vitamin D levels in persons with obesity pursuing bariatric surgery. Materials and Methods: This retrospective cohort study from a single academic medical center investigated adult patients undergoing either primary sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) over a 20-year period. Demographics and serum 25-hydroxyvitamin D3 levels were collected from the first presenting visit to the bariatrics center. Continuous vitamin D3 levels were compared across seasons using a one-way Analysis of Variance (ANOVA). Vitamin D3 categories were examined across seasons using a Chi square test of independence. Results: 1,256 persons pursuing bariatric surgery (SG: N=697, RYGB: N=559) met the inclusion criteria. Baseline vitamin D values were available in 1,071 of the eligible patients. Overall, serum 25-hydroxyvitamin D3 levels showed a significant variation across the seasons of the year (P<0.001), with highest levels during summer (33.52±12.70 ng/mL) and lowest levels during spring (29.72±12.34 ng/mL) and winter (29.90±14.80 ng/mL). Conclusions: This study demonstrates marked seasonal variation in serum 25-hydroxyvitamin D3 in patients with obesity presenting for bariatric surgery. These results emphasize the importance of utilizing tailored supplementation during the spring and winter months to prevent potential deficiency.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalClinical Nutrition Open Science
StatePublished - Feb 2022


  • Fat-soluble Vitamins
  • Nutritional Status
  • Obesity
  • Obesity Surgery
  • Seasonal Variation
  • Vitamin D

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics


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