Capsicum

EVIDENCE: WEAK

Also sold as: Capsicum annuum, cayenne, chili pepper, capsaicin

Capsicum is chili pepper; its heat comes from capsaicin. Studies show capsaicin slightly raises energy use and lowers appetite, and one trial in gestational diabetes found better after-meal glucose with 5 mg of capsaicin a day.

Compiled by iSupplementReviews editorial team ·Researched 2026-10-16 · 3 sources

Type: Botanical fruit extract
Studied dose: About 2–10 mg capsaicinoids/day
Best form: extract with a stated capsaicin or capsaicinoid content
Our rating: WEAK — Mostly small, animal, or traditional evidence

What is capsicum?

Capsicum is the chili pepper genus, and its extracts are sold for metabolism and circulation, mainly because of capsaicin. Capsaicin is the compound that makes peppers hot.

Other names and forms

Cayenne, red pepper, Capsicum annuum fruit extract, capsaicin, and capsiate (a non-pungent relative from sweet peppers).

Where does capsicum come from?

Dried chili pepper fruit.

How does capsicum work in the body?

Capsaicin activates the TRPV1 receptor, the same heat sensor that makes chili burn. This triggers a small rise in energy expenditure and may reduce appetite.

What is capsicum claimed to do?

Boost metabolism, burn fat, improve circulation and support a healthy inflammatory response.

What does the research show?

Claim	Evidence	Dose studied	Verdict
Energy expenditure	Meta-analysis	Capsaicin/capsiate, mg doses	Small positive
Appetite and intake	Meta-analysis	2+ mg capsaicinoids	Small positive
After-meal glucose	One RCT (gestational diabetes)	5 mg capsaicin/day	Early positive
Inflammation (oral)	Little human evidence	—	Insufficient

Energy and appetite

Capsaicin slightly increases energy use and reduces how much people eat. Ludy et al. (2012) and Whiting et al. (2014) found small but consistent effects. Neither suggests capsaicin alone produces meaningful weight loss.

Blood sugar

One trial found better after-meal glucose in gestational diabetes. Yuan et al. (2016) gave women with gestational diabetes chili containing 5 mg of capsaicin a day for 4 weeks and reported lower post-meal glucose and insulin versus control.

What dose was studied?

Goal	Dose	Duration
Energy and appetite	About 2–10 mg capsaicinoids	Single meals to weeks
After-meal glucose	5 mg capsaicin/day	4 weeks

A capsicum extract weight says little unless the capsaicin content is stated.

Side effects

Heartburn, stomach burning, sweating, runny nose.

Drug interactions

Anticoagulants: large amounts may increase bleeding risk (minor, theoretical).
ACE inhibitors: capsaicin may worsen ACE-inhibitor cough (minor).

Who should not take capsicum?

People with ulcers, reflux or irritable bowel who react to spicy food.

What the authorities say

Capsicum is a common food spice and generally recognized as safe in food amounts. Weight and glucose claims for supplements are not recognized by regulators.

What to know about capsicum

Capsaicin has small, consistent effects on energy use and appetite and one positive glucose trial at 5 mg a day. Extracts without a stated capsaicin content can’t be compared with that research.

Frequently asked questions about Capsicum

Does capsaicin help weight loss?

Only a little. Meta-analyses found capsaicin and related compounds slightly increase energy expenditure and reduce how much people eat, effects too small to cause large weight loss alone.

Does chili lower blood sugar?

One 4-week trial in women with gestational diabetes found 5 mg of capsaicin a day improved after-meal glucose and insulin. Broader evidence is limited.

Can capsicum upset the stomach?

Yes. Heartburn, stomach pain and burning are common at higher doses.

References

Products we reviewed containing Capsicum

Based on recorded labels or seller-described formulas. Inclusion does not establish a match to the strains, preparations or amounts studied here; check each review's disclosure limits.