Table 1. Bariatric procedures, their mechanism of action and associated micronutrient deficiency rates.
| Procedure (procedure type) | Anatomical changes (6) | Hormonal changes (7-9) | Reported deficiency rates post-surgery (10) |
|---|---|---|---|
| Sleeve gastrectomy (SG) (restrictive) | Greater curvature of the stomach is removed and a tubular stomach is created | Decreasing ghrelin levels and increasing GLP-1 and PYY levels | Folate: 10–20%; vitamin B6: 0–15%; vitamin B12: 10–20%; vitamin A: 10–20%; vitamin D: 30–70%; iron: 15–45%; copper: 10%; zinc: 7–15% |
| Adjustable gastric band (restrictive) | Gastric pouch (~30 mL) formed by placement of a band/collar around the upper stomach. Constriction is adjusted by varying the volume of saline injected into a subcutaneous port, linked to a balloon within the collar | May increase ghrelin and PYY | Folate: 10%; vitamin B12: 10%; vitamin A: 10%; vitamin D: 30%; iron: 0–32% |
| Gastric bypass (GBP) (restrictive/malabsorptive) | Small (~30 mL) gastric pouch, divided from the larger distal ‘remnant’ stomach and anastomosed to a 75–150 cm length of jejunum (roux-limb). The flow of nutrients bypasses the duodenum and proximal jejunum (biliopancreatic limb) into the common channel of remaining small bowel | Decreasing levels of ghrelin and possibly increasing levels of PYY, GLP-1 and CCK (collectively resulting in appetite suppression) | Thiamin: 12%; folate: 15%; vitamin B12: 30–50%; vitamin A: 10–50%; vitamin D: 30–50%; vitamin E: 10%; iron: 25–50%; copper: 10%; zinc: 20–37% |
| Biliopancreatic diversion duodenal switch (BPD-DS) (restrictive/malabsorptive) | SG with ileoduodenostomy distal to the pylorus. Alimentary and biliopancreatic limbs are created to be of similar length, with common channel varying from 50 to 125 cm | Significantly decreased ghrelin, decreased leptin, increased adiponectin levels ref | Thiamin: 10–15%; folate: 15%; vitamin B6: 10%; vitamin B12: 22%; vitamin A: 60–70%; vitamin D: 40–100%; vitamin E:10%; vitamin K: 60–70%; iron: 25%; copper: 70%; zinc: 25% |
GLP-1, Glucagon-like Peptide 1; PPY, peptide YY; CCK, cholecystokinin.