Mannitol.

Steviol glycosides are used at milligram levels and cannot fill a serving on their own. Mannitol supplies the bulk, mouthfeel and cooling effect while contributing little digestible carbohydrate.

Mogrosides are intensely sweet at tiny doses, so a bulking sugar alcohol is needed to build the powder. Mannitol also masks part of the lingering aftertaste.

Both are poorly absorbed solutes that hold water in the bowel lumen by osmosis. Taken together the water-retaining effect adds up and looseness comes on at lower doses of each.

Mannitol that escapes absorption and inulin both reach the colon, where fermentation raises gas and osmotic water. The gut comfort threshold for the pair is lower than for either alone.

FOS is rapidly fermented in the proximal colon while unabsorbed mannitol adds osmotic water to the same segment. Combining them in one serving stacks the bloating and looseness threshold.

Polydextrose supplies low-calorie bulk with little sweetness, and mannitol supplies bulk with mild sweetness and a cooling effect. Formulators pair them to hit texture targets, and both add osmotic load in the lower gut.

Sorbitol is the stereoisomer of mannitol and behaves the same way in the gut: incompletely absorbed, osmotically active in the lumen and fermented in the colon. Products often carry both because they crystallise and taste differently. Their gastrointestinal effects add, so total polyol load is what matters rather than the individual figure.

Xylitol is a five-carbon polyol that shares mannitol's incomplete small intestinal absorption and its resistance to fermentation by oral bacteria. Confectionery and chewable formats blend them for sweetness and cooling effect. The osmotic load from the two adds together.

Erythritol differs from mannitol in one important respect: it is largely absorbed in the small intestine and excreted unchanged in urine, so less reaches the colon. Blending the two spreads the osmotic load rather than concentrating it. This is a formulation choice with a clear physiological basis.

Psyllium is a gel-forming fibre that holds water in the lumen without being appreciably fermented, while mannitol draws water osmotically and is fermented. Together they change stool water by two different routes. The pairing is common in bowel-regularity formats.

Partially hydrolysed guar gum ferments slowly and more distally than most polyols, which is why it is chosen where gas production is a concern. Combined with mannitol, the fermentation profile is spread across a longer stretch of colon. This is formulation reasoning rather than a measured pairing.

Colonic bacteria are what metabolise the mannitol that escapes small intestinal absorption, and several lactic acid bacteria both consume and produce mannitol in their own metabolism. The composition of a person's microbiota therefore shapes how much gas a given dose generates. The dependency runs from the polyol to the microbe.

Yeasts including Saccharomyces species use polyols such as mannitol as osmolytes and carbon sources under stress conditions. A live yeast preparation taken alongside mannitol meets a substrate it can use. The relevance to what happens in a human colon has not been established.

Glucomannan is a viscous konjac polysaccharide that slows gastric emptying and gut transit, while mannitol speeds transit by holding water in the lumen. In a shared formula the two act against each other on transit. Name the intent before combining them.

No human enzyme hydrolyses mannitol, and supplemental amylases, proteases and lipases do not act on it either, so an enzyme blend does not change how much is absorbed. What enzymes can change is the digestion of other components of the same meal, which alters how much osmotic material arrives together. Read the pairing as unrelated on mannitol itself.

Poorly absorbed magnesium salts hold water in the lumen by the same osmotic mechanism mannitol uses. Taken together the two loads add, and the gastrointestinal effect at a combined dose is larger than either figure suggests alone. This matters most in powdered drink formats where both are present.

Sodium bicarbonate at gram doses contributes its own osmotic and gas load to the gut, on top of the load from an unabsorbed polyol. Effervescent and sports formats often carry both. The combined gastrointestinal effect is the practical point.