Dihydrocapsaicin.

Capsaicin and dihydrocapsaicin together make up the large majority of the capsaicinoid content of chilli, differing only by a saturated versus unsaturated fatty acid tail. Both are agonists at the TRPV1 ion channel and both contribute to a product's declared pungency. Any capsaicinoid extract effectively delivers both, so they are not independent additions.

Capsaicinoids raise sympathetic outflow through TRPV1 activation while caffeine blocks adenosine receptors and slows catecholamine breakdown, so the two arrive at increased sympathetic tone by different routes. That is why they appear together in thermogenic formulas. The effects on heart rate and blood pressure stack, which is the part worth flagging.

Green tea catechins inhibit catechol-O-methyltransferase, which prolongs the action of noradrenaline, and capsaicinoids increase sympathetic outflow upstream of that. The two therefore act on release and on clearance of the same signal. The pairing is a formulation staple and the mechanistic complementarity is well described.

Piperine activates the same TRPV1 channel that capsaicinoids act on, so pungency and warmth stack rather than adding independently. Piperine separately inhibits P-glycoprotein and glucuronidation, which affects how much of a co-administered lipophilic compound survives the gut wall. Both arms of the interaction point the same way and should be counted together.

Gingerol and shogaol act at the same TRPV1 channel as capsaicinoids, which is why both produce warmth on the tongue. Combining them raises the total agonist load on one receptor rather than adding two separate effects. Gastric warmth and discomfort are the practical consequence of stacking them.

Dihydrocapsaicin is a lipophilic vanillylamide that does not dissolve appreciably in water, so a triglyceride carrier is what puts it into solution in a capsule or emulsion. Presenting it in a lipid phase also changes where it contacts the gastric mucosa. This is solubility chemistry and it governs how a capsule is built.

Lecithin emulsifies capsaicinoid oleoresin so it disperses through the gastric contents rather than sitting as concentrated droplets. Even dispersion is one of the reasons encapsulated and emulsified capsaicinoid formats exist. The effect is on distribution in the stomach, not on the pharmacology of the molecule.

Capsaicinoids increase sympathetic signalling that mobilises fatty acids, and carnitine is the carrier that moves long-chain fatty acids into the mitochondrion for oxidation. Thermogenic formulas pair them on that sequential logic. The rationale is mechanistic; the combination itself has not been characterised in people.

Slippery elm mucilage coats the gastric and oesophageal lining and is used in formats where a pungent ingredient causes discomfort. It works against the local irritant contact rather than against the systemic action of the capsaicinoid. The pairing is a tolerability measure and is formulation practice rather than a tested combination.

Two 2026 livestock studies report changes in colon and caecal microbiota composition with dietary capsaicinoid supplementation. That is measured in animals, on composition rather than on a health outcome, so it establishes a plausible interaction with introduced bacterial strains and nothing more. Any co-formulation of the two should be read as mechanistic.

TRPV1 activation in the gut wall increases gastric secretion and speeds transit, which changes the time an enzyme preparation has to act on a meal. Whether that helps or hinders depends on the format and the meal. It is worth naming as a real physiological interaction with a directionally uncertain result.