Chili, black pepper and the capsule in between

Almost everything measured about chili was measured as capsaicin in a capsule. Fifteen randomised trials on 762 adults gave that capsule and took off 0.51 kg, with the confidence interval reaching 0.15 kg at one end, and the reviewers call the effect modest themselves. On blood sugar, fourteen trials found nothing at all, short term or long term. A 2026 pooling of thirteen trials found small drops in total cholesterol and diastolic pressure that did not survive its own sensitivity checks, and the authors say so in their own abstract. None of that was a meal with chili in it. Where the food itself was studied the answer splits in two. Four cohorts covering 564 748 people found lower death rates among chili eaters, and thirteen case-control studies found nearly double the gastric cancer risk in the people who ate the most. Nobody has reconciled those two, and we would rather show you the disagreement than pick a side. One caution about the table below, because it will mislead you otherwise. It puts a vegetable and a spice on the same scale. Green bell pepper at 20 kcal per 100 g is something you eat by the handful. Black pepper at 251 kcal and cayenne at 318 kcal are things you eat by the pinch, and a line of theirs read as a portion turns a spice into a calorie problem it has never been.

The numbers, per 100 g

What your body absorbs

• Two milligrams of black pepper extract made turmeric work where turmeric alone did not. — haemodialysis patients aged 20 to 75 Evidence B source
  Malondialdehyde fell in the turmeric plus piperine group and differed between groups at the end (-0.08 against -0.003 nmol/mL, p = 0.003), as did ferritin (-193.80 against +51.99 mg/mL, p = 0.018); glutathione peroxidase activity fell in the turmeric-only group (p = 0.029); catalase, glutathione reductase and C-reactive protein did not change

What it does to your health

• Cohort data link eating chili pepper with a slightly lower death rate, across half a million followed adults. — 4 cohort studies with 564 748 people, among them 31 527 deaths from all causes, 10 184 from cardiovascular disease and 9 868 from cancer (n = 564748) Evidence C source
  Eating chili pepper ever or more than once a week against none or rare gave all-cause mortality HR 0.87 (95% CI 0.85 to 0.90), cardiovascular 0.89 (0.85 to 0.93) and cancer 0.92 (0.88 to 0.97), with essentially no heterogeneity between studies (I² 0.0 to 21.8%)
• Capsaicin supplements took off half a kilogram, which is the whole of the weight-loss effect. — 15 randomised trials with 762 overweight or obese adults (n = 762) Evidence A source
  Body mass index fell 0.25 kg/m² (95% CI -0.35 to -0.15), body weight 0.51 kg (-0.86 to -0.15) and waist circumference 1.12 cm (-2.00 to -0.24); the waist-to-hip ratio did not change

Safety, limits and interactions

• Case-control studies find nearly double the gastric cancer risk in the people who eat the most chili. — 13 studies with 3 095 cases and 4 761 controls (n = 7856) Evidence C source
  Moderate to high chili consumption gave OR 1.96 (95% CI 1.59 to 2.42); the dose-response was significantly non-linear, with high consumption at OR 2.28 (1.76 to 2.96) and moderate consumption at OR 0.72 (0.36 to 1.41), which is not significant; no publication bias detected (Egger's P = 0.288)
• Splitting by dose, a little capsaicin looked protective and a lot looked harmful in the same analysis. — 10 published articles with 2 452 cases and 3 996 controls (n = 6448) Evidence C source
  Low capsaicin intake gave OR 0.55 (P = 0.003) and medium to high intake OR 1.94 (P = 0.0004); in Korean participants 0.37 against 2.96 and in Mexican 0.63 against 1.57; among people with Helicobacter pylori 0.60 against 1.69; the test of interaction confirmed high intake differs significantly from the protection at low intake

What people believe that the data does not support

• On blood sugar capsaicin did nothing at all, short term or long term. — 14 controlled trials (n = 14 trials) Evidence A source
  Long-term supplementation left fasting glucose unchanged (0.03 mmol/L, 95% CI -0.05 to 0.12) and fasting insulin unchanged (SMD 0.09, -0.04 to 0.22); short-term left 2-hour postprandial glucose (0.06 mmol/L, -0.34 to 0.47) and insulin (1.70 µIU/mL, -3.46 to 6.86) unchanged; dose and form explained part of the heterogeneity

What is still unknown

• On cardiovascular risk markers the 2026 pooling found small effects that did not survive its own sensitivity checks. — 13 randomised controlled trials with 821 adults (n = 821) Evidence A source
  Small and statistically unstable reductions in total cholesterol and diastolic blood pressure that did not survive sensitivity analysis; no significant effect on triglycerides, LDL, HDL, systolic pressure, glucose, insulin, HOMA-IR or HbA1c; heterogeneity above 50% for most outcomes; subgroup analysis hinted that eight weeks or more might help total cholesterol and HDL; GRADE certainty low to very low for most outcomes

The bottom line

If you like chili, eat chili. Nothing here supports buying capsaicin capsules to lose weight, and half a kilogram over the length of those trials is inside the swing between two mornings on the same scale. Two numbers you would want are not in what we hold. The review does not say how long its fifteen trials ran, so half a kilogram has no time attached to it, and silence there reads as permanent when it should read as unknown. It also names no dose. Fifteen trials of capsaicin capsules and no milligram figure to take to a shelf, which is the one number a person looking up capsaicin has come for. The dose question is the one worth holding on to. One meta-analysis of ten case-control studies split people by how much capsaicin they ate and found opposite signs at the two ends, protection at low intake and nearly double the risk at medium to high. Nobody has translated low and high into grams you could measure in a kitchen. Those are case-control studies, where people were asked after a cancer diagnosis what they used to eat, and recall of that kind usually stretches an association rather than shrinking it. Chili eating also travels with salt, smoking and Helicobacter pylori in the populations studied, so the chili may be carrying blame for its company. Black pepper is a different food with a different reason to matter. In haemodialysis patients, 2 mg of piperine added to 3 g of turmeric moved two blood markers that turmeric alone did not, because piperine changes how much of another compound reaches the blood. That same property is why piperine comes up in discussions of drug interactions, and this trial did not measure that side of it. Nobody felt better in it either, because it measured markers. If you take prescription medicine and are considering a concentrated piperine supplement rather than a pinch on your dinner, ask the person who prescribes it.

Sources

1. ppr-r2-07 · randomised double-blind clinical trial
   Turmeric plus piperine was superior to turmeric alone in decreasing MDA and ferritin levels.
   Free Radic Biol Med, 2022 · checked 2026-09-22
2. ppr-r2-01 · meta-analysis of prospective cohort studies
   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 2026-09-22
3. ppr-r2-04 · systematic review and meta-analysis of randomised controlled trials
   Compared with the control group, the supplementation of capsaicin resulted in significant reduction on BMI (WMD: -0·25 kg/m2, 95 % CI = -0·35, -0·15 kg/m2, P < 0·05), body weight (BW) (WMD: -0·51 kg, 95 % CI = -0·86, -0·15 kg, P < 0·05) and waist circumference (WC) (WMD: -1·12 cm, 95 % CI = -2·00, -0·24 cm, P < 0·05).
   Br J Nutr, 2023 · checked 2026-09-22
4. ppr-r2-02 · meta-analysis of case-control studies
   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 2026-09-22
5. ppr-r2-03 · meta-analysis of case-control studies
   The outcomes of our study shows protection (odds ratio [OR] 0.55, P = 0.003) and susceptibility (OR 1.94, P = 0.0004), both significant with low and medium-high intake of capsaicin, respectively, although under relatively heterogeneous conditions (P(heterogeneity) = <0.0001).
   J Gastrointest Cancer, 2014 · checked 2026-09-22
6. ppr-r2-05 · systematic review and meta-analysis of controlled trials
   Capsaicin supplementation seems to have neither acute nor chronic beneficial or detrimental effects on blood glucose and insulin levels.
   Food Funct, 2021 · checked 2026-09-22
7. ppr-r2-06 · systematic review and meta-analysis of randomised controlled trials
   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 2026-09-22