From the Guidelines
After bariatric surgery, monitoring vitamin B12 levels is most concerning, not folate, due to the high risk of deficiency and potential for irreversible neurological damage. While folate deficiency can occur, B12 deficiency is more common and potentially more serious following bariatric procedures, as noted in the 2017 study published in Advances in Nutrition 1. This happens because bariatric surgery, particularly malabsorptive procedures like gastric bypass, reduces the stomach's ability to produce intrinsic factor necessary for B12 absorption and alters the absorption sites in the small intestine.
B12 deficiency can lead to irreversible neurological damage if left untreated, including peripheral neuropathy and cognitive impairment. Patients typically require lifelong B12 supplementation, usually in the form of monthly injections or high-dose oral supplements, as recommended in the 2017 clinical practice guidelines for adult bariatric surgery patients 1. Regular blood monitoring is essential, typically every 3-6 months initially, then annually. Other nutrients requiring monitoring include:
- Iron
- Calcium
- Vitamin D
- Thiamine but B12 deficiency presents the most concerning long-term neurological risks. It is also important to note that patients should be counseled on eating habits and nutrient intake to prevent deficiencies, including consuming high-protein foods and avoiding high-calorie–dense foods and beverages, as suggested in the study 1.
From the Research
Nutritional Deficiencies after Bariatric Surgery
The following are concerning things to check after bariatric surgery:
- Vitamin B12 deficiency 2, 3, 4
- Iron deficiency 2, 3, 4, 5
- Calcium deficiency 2, 3
- Vitamin D deficiency 2, 3, 4, 5
- Folate (Vitamin B9) deficiency 4, 5
- Vitamin A deficiency 4
- Vitamin K deficiency 4
- Selenium deficiency 4
- Zinc deficiency 4
- Copper deficiency 4
Prevention and Treatment
To prevent or treat these nutritional deficiencies, the following are recommended:
- Daily multivitamin and multitrace mineral supplements for all patients scheduled for bariatric surgery 4
- Additional doses of prophylactic supplementation lifelong to maintain optimal micronutrient status 4
- Regular monitoring of serum nutrient levels starting at 3 months after surgery and periodically thereafter 4
- Preconception care for adequate prenatal supplementation in pregnant women who have undergone bariatric surgery 4
- Correction of nutritional intakes before surgery to reduce the risks of developing biological deficiencies 5