Lessons from rodent gastric bypass model of enteric hyperoxaluria.
Study Goal
The researchers aimed to examine the effects of calcium supplementation on hyperoxaluria and bone mineral density in obese rodent models post-Roux-en-Y gastric bypass (RYGB).
Results Summary
Calcium supplementation reduced hyperoxaluria and improved skeletal bone health in RYGB rodents, particularly when combined with a low-fat, low-oxalate diet. Vitamin D supplementation did not rescue bone mineral density loss in severely calcium-deficient animals.
Population
Obese rodent models post-Roux-en-Y gastric bypass (RYGB).
Effective Dosage
Not specified
Duration
Not specified
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
Roux-en-Y gastric bypass (RYGB) | increase | fat in their stool (steatorrhea) | RYGB rodents | up to 40-fold | have up to 40-fold more | #1 |
unabsorbed intestinal fatty acids | increase | enteric hyperoxaluria | RYGB rodents | - | bind calcium and prevent gut calcium oxalate formation, increasing soluble luminal oxalate availability and absorption | #2 |
intraluminal fecal fat exceeding about 175 mg/24 h | increase | oxalate transport | our model | about 175 mg/24 h | more paracellular and transcellular oxalate transport across the distal colon occurred | #3 |
Increasing dietary calcium | decrease | hyperoxaluria | - | - | reduced | #4 |
colonization with Oxalobacter formigenes | decrease | hyperoxaluria | - | - | reduced | #5 |
vitamin B6 supplementation | no change | hyperoxaluria | - | - | did not reduce | #6 |
vitamin D supplementation | no change | bone mineral density loss | RYGB animals, when severely calcium deficient | - | could not rescue | #7 |
a low-fat, low-oxalate diet combined with calcium supplementation | decrease | urinary oxalate | our model | - | can decrease | #8 |
a low-fat, low-oxalate diet combined with calcium supplementation | increase | skeletal bone health | our model | - | can improve | #9 |
PURPOSE OF REVIEW: The aim of the article is to review studies on bone health and oxalate metabolism/therapeutics in the obese rodent model of Roux-en-Y gastric bypass (RYGB) and examine pathways to decrease procedural morbidity. RECENT FINDINGS: Compared with controls, RYGB rodents have up to 40-fold more fat in their stool (steatorrhea) which positively correlates to increased urinary oxalate. These unabsorbed intestinal fatty acids bind calcium and prevent gut calcium oxalate formation, increasing soluble luminal oxalate availability and absorption (enteric hyperoxaluria). When intraluminal fecal fat exceeded about 175 mg/24 h in our model, more paracellular and transcellular oxalate transport across the distal colon occurred. Increasing dietary calcium and colonization with Oxalobacter formigenes reduced hyperoxaluria, whereas vitamin B6 supplementation did not. RYGB animals, when severely calcium deficient, had bone mineral density loss that could not be rescued with vitamin D supplementation. SUMMARY: The findings of hyperoxaluria, steatorrhea, and decreased bone mineral density are seen in both human and rodent RYGB. Our model suggests that a low-fat, low-oxalate diet combined with calcium supplementation can decrease urinary oxalate and improve skeletal bone health. Our model is a useful tool to study renal and bone RYGB effects. Studies of longer duration are required to further evaluate mechanisms of disease and durability of therapeutics.