Peppers: what the capsaicin trials actually measured

Almost everything strong we have on peppers was measured on capsaicin, red pepper powder or paprika extract, not on the pepper you slice into dinner. Keep that in view while reading the numbers. Every study here is about Capsicum, sweet or hot. Black pepper shares the word and a row in the table below, and it is a different plant with no evidence of its own on this page. Across 24 randomised studies, culinary doses of red pepper lowered the respiratory quotient when people were in negative energy balance, which means a larger share of the fuel burned was fat. That is a share, not an amount: the change in energy expenditure itself did not reach statistical significance. In 13 randomised trials with 821 adults the drops in total cholesterol and diastolic blood pressure were small and disappeared once a single study was removed. The observational picture looks friendlier. Four prospective cohorts covering 564748 people found 13 percent lower all-cause mortality among chili eaters (HR 0.87, 95% CI 0.85 to 0.90), with no dose recorded beyond eating chili ever or more than once a week. That is an association among people who already ate chili, not an effect anyone assigned and measured. An umbrella review of 11 systematic reviews read all of this together and called the health effect of chili unclear.

The numbers, per 100 g

How much is actually in it

• Across 140 published datasets the mineral content of pepper fruit varied by growing region and fell over the last decade for iron and zinc, and green pepper held more potassium, magnesium, iron and zinc than hot pepper used as a spice. — 140 publications reporting 649 to 811 datapoints on pepper fruit minerals worldwide (n = 140 publications) Evidence C source
  Global average K 20-25 g/kg, Mg 1-1.5 g/kg, Fe 80-100 mg/kg, Zn 20-40 mg/kg; downward trend for Fe and Zn

What your body absorbs

• In 9 fasting adults given a single dose of paprika oleoresin, the pepper-specific carotenoids capsanthin and capsorubin barely reached the blood, while zeaxanthin, beta-cryptoxanthin and beta-carotene were absorbed. — 9 adult volunteers, single dose after overnight fasting (n = 9) Evidence C source
  Capsanthin and capsorubin bioavailability very low; only free zeaxanthin and beta-cryptoxanthin found in chylomicrons

What it does to your health

• Across 24 randomised studies, culinary doses of red pepper lowered the respiratory quotient during negative energy balance, while changes in energy expenditure did not reach statistical significance. — adults in 22 publications covering 24 randomised controlled studies, including 24-hour respiratory chamber trials (n = 24 randomised studies) Evidence A source
  Respiratory quotient consistently lower (greater fat oxidation); energy expenditure change not significant
• In 13 randomised trials with 821 adults, red pepper or capsaicin produced only small reductions in total cholesterol and diastolic blood pressure, and those reductions disappeared when one study was removed. — 821 adults in 13 randomised placebo-controlled trials of capsaicin or red pepper (n = 821) Evidence A source
  Small reductions in total cholesterol and diastolic blood pressure, not robust to sensitivity analysis; no effect on TG, LDL, HDL, SBP, glucose, insulin, HOMA-IR or HbA1c
• Pooling four prospective cohorts with 564748 people, chili pepper eaters had 13 percent lower all-cause mortality (HR 0.87, 95% CI 0.85 to 0.90). — 564748 adults in 4 prospective cohorts, 31527 deaths from all causes (n = 564748) Evidence C source
  All-cause mortality HR 0.87 (0.85-0.90); CVD HR 0.89 (0.85-0.93); cancer HR 0.92 (0.88-0.97)

Safety, limits and interactions

• Pooling 13 case-control studies with 3095 cases, moderate to high chili consumption carried 1.96 times the odds of gastric cancer (OR 1.96, 95% CI 1.59 to 2.42). — 3095 gastric cancer cases and 4761 controls in 13 studies (n = 7856) Evidence C source
  OR 1.96 (1.59-2.42) for moderate-high intake; OR 2.28 (1.76-2.96) for high intake, no association at moderate intake
• A systematic review of 33 Brazilian studies found no severe acute or chronic dietary risk from pesticide residues overall, yet sweet pepper and tomato in Sao Paulo carried the highest risk values because of organophosphates. — 26 fruit and vegetable samples consumed in Brazilian states, children and adults (n = 33 studies) Evidence C source
  111 residues identified, 16 above the maximum residue limit; cumulative hazard index below 1

What people believe that the data does not support

• An umbrella review of 11 systematic reviews covering 27 findings concluded that the health effect of spicy food and chili peppers is unclear, with direct links to oesophageal, gastric and gallbladder cancer and inverse links to mortality and cardiovascular disease. — humans, 11 systematic reviews and meta-analyses (n = 11 reviews) Evidence C source
  27 findings, direct correlations for three cancers, inverse for metabolism, mortality and cardiovascular disease; non-linear dose-response for gastric cancer

Who this works differently for

• Among 383 Saudi patients with inflammatory bowel disease and 390 controls, daily spicy food went with higher odds of Crohn disease (OR 1.61, 95% CI 1.11 to 2.33) but not ulcerative colitis. — 157 patients with ulcerative colitis, 226 with Crohn disease, 390 controls in Saudi Arabia (n = 773) Evidence C source
  Crohn disease OR 1.61 (1.11-2.33); ulcerative colitis OR 1.03 (0.67-1.60)

The bottom line

The evidence against is real and it sits in the stomach. Pooling 13 case-control studies with 3095 gastric cancer cases and 4761 controls, moderate to high chili intake carried 1.96 times the odds of gastric cancer (95% CI 1.59 to 2.42), rising to 2.28 at high intake, with no association at moderate intake on its own. Case-control means people recalled what they ate after they were already ill, so this is weaker than a trial, and it is still the main reason to stop treating chili as free medicine. The same umbrella review that called the overall effect unclear also found direct links to oesophageal, gastric and gallbladder cancer alongside the inverse links to mortality. Both sets of findings are in the same body of work, and nobody has resolved them. If you have Crohn disease, one Saudi study of 383 patients with inflammatory bowel disease and 390 controls found daily spicy food went with 1.61 times the odds of Crohn disease (95% CI 1.11 to 2.33) and no link at all with ulcerative colitis. It is a single clinic, intake was self-reported, and no dose or pepper type was recorded, so read it as a reason to watch your own reaction rather than as a rule. Colour tells you more than the heat does. Across 140 published datasets, green pepper held more potassium, magnesium, iron and zinc than hot pepper used as a spice, regional variation was wide, and iron and zinc fell over the last decade. The red pigments that paprika is sold for barely arrive in the blood. In 9 fasting adults given paprika oleoresin, capsanthin and capsorubin were close to absent from the blood, while zeaxanthin, beta-cryptoxanthin and beta-carotene were absorbed. On residues, a systematic review of 33 Brazilian studies found no severe acute or chronic dietary risk overall, with the cumulative hazard index below 1, yet sweet pepper and tomato in Sao Paulo carried the highest risk values because of organophosphates, and 16 of 111 residues sat above the maximum residue limit. That is Brazilian market data and it does not describe your shop. Now what we do not have, because that is part of the answer. We found nothing on what cooking does to a pepper, so roasting, grilling and frying are unmeasured here. We found nothing on portion size as people actually eat peppers, so every number above is a population average rather than a plate. We found nothing on interactions with medicines for peppers as a food, since our drug layer is indexed by nutrient and holds no entry for a whole vegetable. That is a gap in our search, and it is not evidence that no interaction exists. One more boundary worth naming. Every study here is about Capsicum, sweet or hot. Black pepper shares the word and the USDA table on this page, and it is a different plant with no evidence of its own in what we read.

Sources

1. pprs-r5-05 · pooled crop composition datasets
   There had been a downward trend in pepper fruit nutritional quality over the last decade, especially for Fe and Zn.
   Food Res Int, 2024 · checked 2026-09-23
2. pprs-r5-06 · human absorption study
   The bioavailability of the pepper-specific carotenoids capsanthin and capsorubin from paprika oleoresin is very low.
   Br J Nutr, 2003 · checked 2026-09-23
3. pprs-r5-01 · meta-analysis of RCTs
   Twenty-two publications representing 24 randomized controlled studies were synthesized...Capsaicin significantly reduced RQ in negative-EB and in high-protein conditions, indicating greater fat oxidation.
   Nutr Rev, 2026 · checked 2026-09-23
4. pprs-r5-02 · meta-analysis of RCTs
   Thirteen RCTs (n = 821 participants) were included...Red pepper/capsaicin supplementation was associated with small, statistically unstable reductions in total cholesterol and diastolic blood pressure; however, these effects were not robust to sensitivity analyses and should be interpreted as low-confidence estimates.
   Nutr Metab Cardiovasc Dis, 2026 · checked 2026-09-23
5. pprs-r5-03 · pooled prospective cohorts
   Compared to none or rare consumption of chili pepper, consumption of chili pepper (ever or more than once a week) could significantly reduce the risk of all-cause mortality (summary adjusted HR: 0.87, 95% CI: 0.85, 0.90), CVD-specific mortality (summary adjusted HR: 0.89, 95% CI: 0.85, 0.93), and cancer-specific mortality (summary adjusted HR: 0.92, 95% CI: 0.88, 0.97).
   Int J Vitam Nutr Res, 2023 · checked 2026-09-23
6. pprs-r5-04 · pooled case-control studies
   13 studies (3,095 cases and 4,761 controls) were included in the meta-analysis. A 1.96-fold increased risk of GC was shown for the moderate-high chili consumption (OR = 1.96, 95%CI =1.59-2.42).
   Nutr Cancer, 2021 · checked 2026-09-23
7. pprs-r5-08 · systematic review of monitoring data
   We did not identify severe acute and chronic dietary risks, but the highest risk values were observed in São Paulo and Santa Catarina, associated with the consumption of tomatoes and sweet peppers due to the high concentrations of organophosphates.
   Chemosphere, 2023 · checked 2026-09-23
8. pprs-r5-09 · umbrella review
   Eleven systematic reviews and meta-analyses with a total of 27 findings are identified. The health effect of consuming spicy food and chili peppers is unclear.
   Mol Nutr Food Res, 2022 · checked 2026-09-23
9. pprs-r5-07 · case-control study
   Daily consumption of spicy food was significantly associated with higher odds of CD (OR = 1.61; 95% CI: 1.11, 2.33), but not UC (OR = 1.03; 95% CI: 0.67, 1.60).
   Nutrition, 2026 · checked 2026-09-23