Evidence for the Necessity to Systematically Assess Micronutrient Status Prior to Bariatric Surgery

Bariatric surgery has been proven the most effective treatment of morbid obesity, but micronutrient deficiency following bariatric surgery is a major concern. Increasing evidence points to a generally poor micronutrient status in obese subjects.

We assessed micronutrient status in 232 morbidly obese subjects (BMI ≥ 35 kg/m²) prior to bariatric surgery. Serum albumin, calcium, phosphate, magnesium, ferritin, hemoglobin, zinc, folate, vitamin B₁₂, 25-OH vitamin D₃, and intact parathormone (iPTH) were determined. In a sub-sample of 89 subjects, we additionally assessed copper, selenium, vitamin B₁, B₃, B₆, A, and E levels.

Deficiencies were found in 12.5% of the subjects for albumin, 8.0% for phosphate, 4.7% for magnesium, 6.9% for ferritin, 6.9% for hemoglobin, 24.6% for zinc, 3.4% for folate, and 18.1% for vitamin B₁₂. In addition, 25.4% showed a severe 25-OH vitamin D₃ deficiency, which was accompanied by a secondary hyperparathyroidism in 36.6% cases. Prevalence of albumin deficiency (p < 0.007) and of anemia (p < 0.003; in women only) significantly increased with BMI. Of note, 48.7% of the subjects showed at least one of the most prevalent deficiencies, i.e., vitamin B₁₂, zinc and severe 25-OH vitamin D₃ deficiency. In the sub-sample, 32.6% showed a selenium, 5.6% a vitamin B₃, 2.2% a vitamin B₆, and 2.2% a vitamin E deficiency. Copper, vitamin B₁, and vitamin A deficiency was found in none of the subjects.

Data indicate a high prevalence of micronutrient deficiencies in morbidly obese subjects. Based on these results, we strongly recommend a systematic assessment of the micronutrient status in all candidates for bariatric surgery.