https://sci-hub.ru/10.2174/138161210790945922
https://pubmed.ncbi.nlm.nih.gov/27779477/
NSAID ulcer incidence in humans varies widely from 10% - 70%,
when feeding 0.3% -> 3% dietary insoluble fiber it escalates the amount of lesions NSAIDs create
replacing the fiber with only pectin fiber instead (forms a gel kind of), they basically dont cause lesions at least lower down


0.3% fiber vs 3% ^
C & A refer to gastric, D duodenum, the numbers progressively through small intestine distance
(~3g vs ~30g fiber probably.
1% might still develop)
10% pectin instead, no lesions
(replacing with pectin or guar gum is important instead of just removing, for bowel movements, and so it can be processed by bacteria to keep SCFA production up instead of eating the mucosa which gets degraded if u just go low fiber otherwise)
for reoccurrence, >10g apple pectin a day made it worse in the duodenum https://pubmed.ncbi.nlm.nih.gov/3278367/ and the earlier image showed it worse in the duodenum for some reason
takeaway:
if want to heal chronic ulcers in small intestine & probably early part of the large intestine / colon until the insoluble fiber gets broken down by bacteria, its optimal to have max 3g insoluble fiber over a day, and the rest replaced with pectin to keep bowel movements.
{its interesting fruit has pectin basically matching the insoluble fiber content}
& alternatively
can match the insoluble fiber intake with grams of pectin (bumping up a little extra) or guar gum simultaneously at meals , can be enough to protect. (but pectin might especially bind minerals when taking high amounts simultaneously with food and wouldnt give the same effect separated from insoluble fiber intake)

https://sci-hub.ru/10.1007/s10620-009-0893-2
