Dehydrocholic acid.

Ox bile supplies conjugated bile salts that form mixed micelles and carry dietary fat and fat-soluble vitamins across the unstirred water layer. Dehydrocholic acid does the opposite job: it drives water and electrolyte secretion into bile without contributing meaningful micelle-forming capacity. Combining them is not doubling one effect, it is pairing a flow agent with a solubilising agent.

Fat-soluble vitamins need micellar solubilisation by conjugated bile salts to be absorbed. Dehydrocholic acid is a poor detergent because its three oxo groups replace the hydroxyls that give natural bile acids their amphipathic face. So increasing bile volume with it does not by itself increase the micellar capacity that vitamin D uptake depends on.

Vitamin K absorption follows the same micellar route as the other fat-soluble vitamins and falls when bile salt concentration drops below the critical micellar level. A hydrocholeretic increases the aqueous fraction of bile rather than the bile salt concentration in it. Read the pairing as a caution against assuming more bile flow means better vitamin uptake.

Medium-chain triglycerides are absorbed largely without micelle formation and travel by the portal route rather than through chylomicrons. That makes them the lipid least dependent on bile salt sufficiency. Where bile salt-mediated solubilisation is the limiting step, medium-chain fat gets through when long-chain fat does not.

Pancreatic lipase hydrolyses triglyceride to fatty acids and monoglycerides, and bile salts then carry those products into micelles. The two steps are sequential and neither substitutes for the other. Bile-acid ingredients are paired with lipase in digestive formulations because they cover different halves of the same sequence.

The liver conjugates bile acids at the C24 carboxyl with either taurine or glycine, which lowers the pKa and keeps the molecule ionised and membrane-impermeant through the gut. Taurine availability is one determinant of the taurine to glycine conjugate ratio. This is the enzymatic context any exogenous bile acid enters.

Glycine is the other conjugating amino acid for bile acids and normally the more abundant of the two in humans. Conjugation is what keeps a bile acid in the intestinal lumen rather than letting it diffuse passively across the mucosa. The ratio between the two conjugates shifts with the supply of each amino acid.

Viscous soluble fibres bind bile acids in the gut lumen and carry them to the colon instead of letting them return through the ileal transporter. That interrupts enterohepatic recirculation and increases faecal bile acid loss. Taken at the same time, a fibre load reduces the luminal bile acid concentration a bile ingredient was meant to raise.

Activated charcoal adsorbs bile acids along with almost everything else of similar size in the gut lumen. Anything intended to act inside the intestine should be separated from it by several hours. This is a general timing rule rather than a property specific to this compound.

Artichoke leaf is a long-standing choleretic in European herbal practice, with cynarin and caffeoylquinic acids as its marker compounds. It appears alongside bile acid ingredients in bile-flow formulations because both are aimed at the same physiology from different directions. The pairing rests on formulation convention and monograph use rather than on trials of the combination.

Silymarin appears in the same category of hepatobiliary products as bile acid ingredients, and both act on liver and bile physiology rather than on digestion in the lumen alone. The two have not been tested together in any way that would justify a combined claim. This is formulation practice.

Dandelion root is used traditionally as a bitter that stimulates bile secretion, and it shares shelf space with bile acid ingredients for that reason. The traditional use is well documented. The physiological size of the effect is not. Read the pairing as convention rather than as a demonstrated combination.