So here are some basics about digestion, disaccharides and Balrogs.
Fats are broken down into fatty acids and glycerol
Protein is broken down into single amino acids
Carbohydrates are broken down into single sugars
Pancreatic enzymes get all the press and we often forget about the brush border enzymes- peptidases and disaccharidases.
Peptidases break petides (very small proteins) into single amino acids
Disaccharidases break double sugars (disaccharides) into single sugars
What can and can’t pass?
Amino acids (single proteins) pass the brush border
Di & Tri Peptides (very small proteins) pass the brush border
Single sugars pass the brush border
Disaccharides can’t pass brush border
(they need disaccharide enzyme digestion first)
This is why the diets that treat SIBO avoid all but the single sugars (honey and ripe fruit) which can pass the brush border freely.
For more on how disaccharides are problematic in SIBO, see The Gut/Brain/Food Connection, and/or Breaking the Vicious Cycle, both by Elaine Gottschall.