Gastric Band and Nutrient Absorption
No, gastric bands do not delay nutrient absorption—they are purely restrictive devices that reduce stomach capacity and slow gastric emptying, but they do not alter the absorptive function of the small intestine. 1
Mechanism of Gastric Banding
The adjustable gastric band (AGB) functions exclusively through mechanical restriction:
- An inflatable silicone band is placed around the upper stomach, creating a small pouch (approximately 15-30 mL) with a narrow outlet to the lower stomach 1
- The band reduces stomach capacity and appetite through physical restriction alone, without any malabsorptive component 1
- Food passage is slowed through the restricted outlet, but once nutrients reach the small intestine, absorption proceeds normally 1
Contrast with Malabsorptive Procedures
This is fundamentally different from procedures that actually impair nutrient absorption:
- Roux-en-Y gastric bypass (RYGB) bypasses the duodenum and proximal jejunum, creating true malabsorption by diverting nutrients away from key absorptive sites 1
- Biliopancreatic diversion creates a short "common channel" (50-100 cm) where digestion and absorption occur, resulting in profound malabsorption 1
- Gastric banding involves no intestinal bypass or rearrangement—the entire small intestine remains intact and functional 1
Clinical Implications for Medication Management
While absorption is not impaired, gastric bands do affect medication delivery:
- Extended-release and delayed-release formulations should be avoided entirely due to altered gastric anatomy, reduced stomach capacity, and changes in gastric emptying 2
- The small upper pouch and restricted outlet disrupt the prolonged gastric residence time required for proper dissolution of extended-release medications 2
- Switch to immediate-release alternatives using liquid formulations, chewable tablets, or crushed immediate-release tablets when possible 2
- Oral contraceptives should be switched to non-oral methods due to concerns about unreliable absorption from altered gastric emptying patterns 2
Important Caveats
The key distinction is between delayed gastric emptying (which occurs) versus impaired intestinal absorption (which does not occur):
- Gastric emptying is significantly slowed by the mechanical restriction, which can affect the rate at which medications reach the small intestine 2, 3
- Once nutrients or medications pass through the band and reach the small intestine, absorption capacity remains normal 1
- Micronutrient deficiencies after gastric banding are primarily due to reduced oral intake, not malabsorption, unlike RYGB or biliopancreatic diversion 1
Medications to completely avoid include NSAIDs, aspirin, oral bisphosphonates, corticosteroids, and potassium chloride tablets due to risk of gastric irritation and ulceration in the small pouch, not absorption concerns 2