Cayenne (Capsaicin)

Capsaicin is the principal compound in the capsaicinoid family, responsible for the heat of chilli peppers. Cayenne is one of several Capsicum varieties used as a source.

Potency is measured in Scoville heat units, and supplements are often standardised that way rather than by capsaicinoid weight. Capsimax and similar branded preparations use a coating that delays release until past the stomach, which is the main reason they exist — uncoated capsaicin at an effective dose is genuinely unpleasant to swallow.

Capsiate is a related compound from sweet peppers that shares much of the biological activity without the heat. It is used where the thermogenic effect is wanted without the burn, and is worth knowing about if capsaicin causes you problems.

Capsaicin activates TRPV1, a receptor found on sensory nerve endings that normally responds to heat. Activating it produces the sensation of burning without any actual temperature change, which is why chilli feels hot.

That same activation triggers a sympathetic nervous system response, increasing noradrenaline release and modestly raising energy expenditure and fat oxidation. There is also evidence for effects on appetite and on the amount eaten at a subsequent meal.

Here is the part that gets left out: TRPV1 receptors desensitise with repeated exposure. That is precisely why regular chilli eaters tolerate heat that would floor someone else. The same desensitisation applies to the thermogenic response, which means the effect diminishes with continuous daily use rather than persisting indefinitely.

Meta-analyses of capsaicinoid supplementation have reported measurable increases in energy expenditure and fat oxidation, along with modest reductions in appetite and food intake. The direction of effect is reasonably consistent.

The magnitude is the issue. Increases in daily energy expenditure are typically in the region of 50 kilocalories, which is real but trivial against a diet. Anyone expecting a supplement to do the work of a deficit will be disappointed.

Most trials run for weeks rather than months, which means the desensitisation question is largely unstudied. Given how well established TRPV1 desensitisation is in other contexts, it is reasonable to assume the effect wanes, and to cycle accordingly rather than take it continuously.

Capsaicin is a food compound eaten in quantity across much of the world and is well tolerated by most people. The dominant complaint is gastrointestinal: burning, stomach discomfort, heartburn and, at higher doses, nausea.

Coated preparations largely solve this by releasing past the stomach. Taking uncoated capsaicin on an empty stomach is the reliable way to have a bad time.

Because it raises sympathetic activity, take care combining it with other stimulants, and speak to your doctor before use if you take regular medication or if your blood pressure is being managed. Anyone prone to reflux or stomach irritation should approach cautiously.