Home Ingredients Bell Pepper (Capsicum annuum)

Bell Pepper (Capsicum annuum)

Capsicum annuum
Evidence Level
Preliminary
5 Clinical Trials
6 Documented Benefits
1/5 Evidence Score

Bell peppers are the sweet, non-pungent fruits of Capsicum annuum, eaten green (unripe) or ripened to yellow, orange or red. They belong to the same species as many chili peppers, but bell types carry a gene variant that blocks capsaicin, so they have no heat and differ from capsaicin supplements and capsanthin extracts. Bell peppers are a rich food source of vitamin C, and red ones supply beta-carotene, beta-cryptoxanthin and the red pigment capsanthin, while green ones carry more lutein and orange ones are notable for zeaxanthin. Human research on bell pepper itself is thin: one short, unblinded juice trial reported conflicting statements on post-meal blood sugar, feeding studies show pepper pigments are absorbed, and a bell pepper fiber extract was tested separately. Bell pepper allergy is rare but can be serious, mostly in people with pollen allergies.

Studied Dose No supplement dose. One trial used 100 ml of bell pepper juice twice daily for 4 days; a feeding study used a set serving of fresh red bell pepper. A bell pepper fiber extract (RG-I) was tested at 0.3 or 1.5 g/day for 28 days.
Active Compound Whole sweet pepper fruit (Capsicum annuum, non-pungent cultivars): vitamin C, carotenoids (beta-carotene, beta-cryptoxanthin, capsanthin, lutein and zeaxanthin, varying with color) and dietary fiber including pectic polysaccharides; capsaicinoids are absent or not detectable.

Benefits

A rich food source of vitamin C

Per USDA data, raw sweet red pepper supplies about 128 mg of vitamin C per 100 g, so a medium red pepper (119 g) carries roughly 150 mg. Raw green pepper has about 80 mg per 100 g, and boiled green pepper about 74 mg. These are food composition figures; no trial has tested bell pepper as a way to raise vitamin C status.

Supported by Trial 2, Trial 3

Carotenoids that differ by pepper color

Raw red pepper is listed at about 1,620 mcg beta-carotene and 490 mcg beta-cryptoxanthin per 100 g, both provitamin A carotenoids. Green pepper has far less beta-carotene but more lutein plus zeaxanthin (341 vs 51 mcg). In a lab survey of 33 fruits and vegetables, orange pepper had the highest zeaxanthin share of any vegetable tested.

Supported by Trial 4, Trial 1

Pepper pigments are absorbed and show up in blood and urine

In a small study, capsanthin and related pigments plus lutein and zeaxanthin were found in blood plasma after drinking paprika (red sweet pepper) juice. In a feeding study of 14 volunteers, eating fresh red bell pepper produced urinary metabolites most likely derived from capsanthin and capsianosides. These studies show absorption only, not a health effect.

Supported by Trial 3, Trial 4

Post-meal blood glucose in a short juice add-on trial

In 50 adults with type 2 diabetes in a yoga program, adding 100 ml of bell pepper juice twice daily for 4 days was compared with yoga alone. The authors reported no between-group difference in overall fasting and post-meal glucose, yet also a significant drop in post-meal glucose and systolic blood pressure. It was unblinded, very short and had no placebo.

Supported by Trial 1

Immune cell activity with an enriched bell pepper fiber extract

In a 28-day placebo-controlled study of 60 healthy adults, a pectic polysaccharide extract from bell pepper (RG-I, 0.3 or 1.5 g/day) raised the activity of blood granulocytes in an ex vivo test by about 15% and 20% versus placebo; NK cell activity did not change detectably. The maker of the extract funded the study. This is a concentrated extract, not whole bell pepper.

Supported by Trial 2

Learning tasks in aging mice fed red bell pepper (animal study)

Senescence-accelerated mice fed a diet with 20% freeze-dried red bell pepper powder learned a passive avoidance task better than mice on a standard diet. This is a single mouse study at a very high dietary share and has not been tested in people.

Supported by Trial 5

Mechanism of action

1

Why bell peppers have no heat

Capsaicin production needs a working Pun1 gene, which encodes an acyltransferase. Non-pungent peppers carry a recessive pun1 version with a large deletion, so the pathway stalls. In one HPLC comparison of eight C. annuum varieties, capsaicinoids were not detectable in bell pepper, although that study also found capsaicinoid levels in several varieties, bell pepper included, rose under high growing temperatures.

2

Water-soluble vitamin C and fat-soluble carotenoids

Vitamin C sits in the watery flesh of the fruit, while the carotenoids are fat-soluble pigments that build up as the fruit ripens from green to red. Beta-carotene and beta-cryptoxanthin can be converted to vitamin A, which is why USDA lists red pepper at 157 mcg vitamin A (RAE) per 100 g against 18 mcg for green.

3

Pectic fiber fermented by gut microbes (lab finding)

Bell pepper cell walls contain rhamnogalacturonan-I (RG-I), a pectic polysaccharide. In laboratory cultures with human fecal bacteria, an RG-I extract from bell pepper was fermented to short-chain fatty acids and stimulated immune cell responses in vitro. These are lab results with a concentrated extract.

Clinical trials

1
Bell Pepper Juice Added to Yoga: 4-Day Randomized Trial in 50 Adults (no placebo)
PubMed

Randomized, open (unblinded) trial comparing 100 ml of bell pepper (Capsicum annuum var. grossum) juice twice daily plus an integrated yoga program with the yoga program alone, for 4 days. Funding is not stated in the abstract; a corrigendum was later published. (Nagasukeerthi et al. 2017, Complement Ther Med)

50 adults aged 34 to 69 with type 2 diabetes; the authors are based at a yoga university in Bengaluru, India.

The authors report no significant difference between groups in overall (fasting and post-meal) blood glucose, but in the same abstract report a significant reduction in post-meal glucose, systolic blood pressure, pulse pressure and two heart workload indices in the juice group versus control. Fasting glucose did not differ. Four days, no blinding and no placebo drink, so the result is weak.

2
Bell Pepper RG-I Fiber Extract and Immune Cell Activity: 28-Day Placebo-Controlled Study (maker-funded)
PubMed

Randomized, double-blind, placebo-controlled proof-of-concept study of an enriched bell pepper pectic polysaccharide extract (bpRG-I) at 0.3 or 1.5 g/day versus maltodextrin, stirred into an instant cappuccino drink, within a paper that also reports lab work. Funded by Nutrileads, which holds patents on the extract. (McKay et al. 2021, Nutrients)

60 healthy adults aged 20 to 65 in Germany; 57 included in the analysis.

On day 28, granulocyte phagocytic activity (an ex vivo test) rose about 15% (low dose) and 20% (high dose) versus placebo; there was no change by day 5. NK cell activity varied too much to show any significant change. Tolerability was rated very good, with one case of mild flatulence judged possibly related. No infection or symptom outcomes were measured.

3
Fresh Red Bell Pepper Intake and Urinary Metabolites in 14 Volunteers (feeding study)
PubMed

Two-phase dietary intervention comparing a control phase without any bell pepper or paprika products to a phase eating a defined amount of fresh red bell pepper, with urine metabolomics. (Schulz et al. 2021, J Agric Food Chem)

14 volunteers.

Urine metabolite profiles differed significantly between phases because of the bell pepper intake. Seven new glucuronidated metabolites, most likely derived from capsanthin and capsianosides, were identified as possible intake biomarkers. No health outcome was measured.

4
Plasma Carotenoids After Paprika (Red Sweet Pepper) Juice (human absorption study)
PubMed

Human study identifying carotenoids in blood plasma after drinking paprika juice. (Etoh et al. 2000, Biosci Biotechnol Biochem)

Male subject(s); the abstract does not state the number.

Capsanthin, its metabolite capsanthone, cucurbitaxanthin A, 11-cis-capsanthin, lutein and zeaxanthin were identified in plasma. This shows pepper carotenoids are absorbed; there was no control group and no health outcome.

5
Red Bell Pepper Diet and Learning in Aging Mice (Animal Study, Not a Human Trial)
PubMed

Diet study in senescence-accelerated SAMP8 mice fed 20% (w/w) freeze-dried red bell pepper powder versus a standard diet; the first author is affiliated with the research institute of Kagome Co., Ltd. (Suganuma et al. 1999, J Nutr Sci Vitaminol (Tokyo))

SAMP8 mice; no people.

Mice on the red bell pepper diet showed much better acquisition in a passive avoidance task than controls. An animal result at a very high dietary share; it says nothing directly about memory in people.

Side effects and drug interactions

Common Potential side effects

Bell pepper is a common food and is well tolerated by most people. Allergy to Capsicum is described as rare, but a case of anaphylaxis after eating raw bell pepper has been reported.
People with birch pollen or other pollen allergies may react: bell peppers can contain profilin and, in some strains, a Bet v 1 like protein that cross-react with birch pollen. Paprika, the dried red pepper spice, is also part of the mugwort-birch-celery-spice cross-reaction pattern.
Named bell pepper allergens include Cap a 1 (an osmotin-like protein), Cap a 2 (profilin) and Cap a 7 (a gibberellin-regulated protein linked to cedar pollen, peach and orange reactions). Anyone with throat tightness, hives or swelling after eating peppers should avoid them and see an allergist.
Concentrated bell pepper fiber extract (RG-I) at up to 1.5 g/day for 28 days was well tolerated in one study; the only possibly related effect was one case of mild flatulence.

Important Drug interactions

No drug interaction studies of bell pepper as a food or juice have been found.
In the one juice trial, participants with type 2 diabetes had post-meal glucose changes reported; anyone on glucose-lowering or blood pressure medicines who plans to drink large amounts of pepper juice daily should discuss it with their doctor.

Frequently asked questions about Bell Pepper (Capsicum annuum)

Do bell peppers contain capsaicin?

Essentially no. Bell peppers carry a version of the Pun1 gene with a large deletion, which blocks capsaicin production, and in one laboratory comparison capsaicinoids were not detectable in bell pepper. This is why bell peppers taste sweet rather than hot and why they are not a substitute for capsaicin or cayenne supplements.

Is eating bell pepper the same as taking a capsanthin or paprika extract?

No. Red bell peppers contain capsanthin, and their pigments are absorbed when eaten, but capsanthin and paprika oleoresin supplements are concentrated extracts studied as separate materials. Whole bell pepper also supplies vitamin C, fiber and, depending on color, beta-carotene, lutein and zeaxanthin.

Which color of bell pepper has the most vitamin C and carotenoids?

In USDA data, raw red pepper has more vitamin C than green (about 128 vs 80 mg per 100 g) and far more beta-carotene and beta-cryptoxanthin. Green pepper has more lutein plus zeaxanthin than red, and orange peppers stood out for zeaxanthin in a laboratory survey.

Does cooking bell peppers destroy the vitamin C?

Some is lost, but not most. USDA lists raw green pepper at about 80 mg of vitamin C per 100 g and boiled, drained green pepper at about 74 mg per 100 g. Cooking methods vary, so actual losses depend on time, heat and water used.

Can someone be allergic to bell peppers?

Yes, though it is rare. Reported reactions often involve people with pollen allergies such as birch or mugwort, because some pepper proteins (such as profilin) cross-react with pollen proteins; one case report also linked a pepper protein, Cap a 7, to Japanese cedar pollen. A case of anaphylaxis after raw bell pepper has been reported, so anyone with symptoms should see an allergist.

What is Bell Pepper?

Bell peppers are the sweet, non-pungent fruits of Capsicum annuum, eaten green (unripe) or ripened to yellow, orange or red. They belong to the same species as many chili peppers, but bell types carry a gene variant that blocks capsaicin, so they have no heat and differ from capsaicin supplements and capsanthin extract…

What is Bell Pepper used for?

NutraSmarts does not list Bell Pepper under a health category. What the research covers: Per USDA data, raw sweet red pepper supplies about 128 mg of vitamin C per 100 g, so a medium red pepper (119 g) carries roughly 150 mg. Raw green pepper has about 80 mg per 100 g, and boiled green pepper about 74 mg.

What is the recommended dosage of Bell Pepper?

No supplement dose. One trial used 100 ml of bell pepper juice twice daily for 4 days; a feeding study used a set serving of fresh red bell pepper. A bell pepper fiber extract (RG-I) was tested at 0.3 or 1.5 g/day for 28 days. Always follow the product label and check with a healthcare provider for personal advice.

Is Bell Pepper safe, and does it have side effects?

Side effects and cautions reported for Bell Pepper include: Bell pepper is a common food and is well tolerated by most people. Allergy to Capsicum is described as rare, but a case of anaphylaxis after eating raw bell pepper has been reported. It may also interact with some medications. Bell Pepper is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Bell Pepper interact with any medications?

Possible interactions include: No drug interaction studies of bell pepper as a food or juice have been found. In the one juice trial, participants with type 2 diabetes had post-meal glucose changes reported; anyone on glucose-lowering or blood pressure medicines who plans to drink large amounts of pepper juice… If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Bell Pepper?

NutraSmarts rates the evidence for Bell Pepper as Preliminary (1 out of 5). It is backed by 5 study summaries and 16 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(16 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Nagasukeerthi P, Mooventhan A, Manjunath NK. Short-term effect of add on bell pepper (Capsicum annuum var. grossum) juice with integrated approach of yoga therapy on blood glucose levels and cardiovascular functions in patients with type 2 diabetes mellitus: A randomized controlled study. Complement Ther Med. 2017;34:42-45. doi: 10.1016/j.ctim.2017.07.011.PubMedUsed to support: Randomized, open (no placebo) 4-day trial in 50 adults with type 2 diabetes in India: 100 ml of bell pepper juice twice daily added to a yoga program versus the yoga program alone. The authors report no significant between-group difference in overall fasting and post-meal blood glucose, but also report a significant reduction in post-meal glucose and systolic blood pressure versus control. A corrigendum to the paper was published in 2018.
  2. McKay S, Oranje P, Helin J, Koek JH, Kreijveld E, van den Abbeele P, Pohl U, Bothe G, Tzoumaki M, Aparicio-Vergara M, Mercenier A, Schols H, Albers R. Development of an Affordable, Sustainable and Efficacious Plant-Based Immunomodulatory Food Ingredient Based on Bell Pepper or Carrot RG-I Pectic Polysaccharides. Nutrients. 2021;13(3):963. doi: 10.3390/nu13030963.PubMedUsed to support: In vitro work plus a randomized, double-blind, placebo-controlled 28-day study in 60 healthy adults (57 analyzed) of an enriched bell pepper pectic polysaccharide extract (bpRG-I, 0.3 or 1.5 g/day in an instant cappuccino drink) versus maltodextrin: granulocyte phagocytic activity rose about 15% and 20% versus placebo, NK cell activity showed no detectable change, and the extract was well tolerated. Funded by Nutrileads, which employs several authors and holds patents on the extract. An extract, not bell pepper food.
  3. Schulz M, Hövelmann Y, Hübner F, Humpf HU. Identification of Potential Urinary Biomarkers for Bell Pepper Intake by HPLC-HRMS-Based Metabolomics and Structure Elucidation by NMR. J Agric Food Chem. 2021;69(45):13644-13656. doi: 10.1021/acs.jafc.1c04210.PubMedUsed to support: Dietary intervention in 14 volunteers with a control phase (no bell pepper or paprika products) and a phase eating a defined amount of fresh red bell pepper: the urine metabolome differed between phases, and seven glucuronidated metabolites most likely derived from capsanthin and capsianosides were identified as possible intake biomarkers. Shows these compounds are absorbed and excreted; no health outcome.
  4. Etoh H, Utsunomiya Y, Komori A, Murakami Y, Oshima S, Inakuma T. Carotenoids in human blood plasma after ingesting paprika juice. Biosci Biotechnol Biochem. 2000;64(5):1096-8. doi: 10.1271/bbb.64.1096.PubMedUsed to support: Human study of carotenoids in blood plasma after drinking paprika (red sweet pepper) juice: capsanthin, capsanthone, cucurbitaxanthin A, 11-cis-capsanthin, lutein and zeaxanthin were identified in plasma of a male subject. Absorption data only; the abstract does not give a subject count or any health outcome.
  5. Sommerburg O, Keunen JE, Bird AC, van Kuijk FJ. Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes. Br J Ophthalmol. 1998;82(8):907-10. doi: 10.1136/bjo.82.8.907.PubMedUsed to support: Laboratory analysis of 33 fruits and vegetables, two juices and egg yolk by HPLC: orange pepper had the highest zeaxanthin share of any vegetable tested (37% of total carotenoids). Composition data, not a feeding study.
  6. González-Zamora A, Sierra-Campos E, Luna-Ortega JG, Pérez-Morales R, Rodríguez Ortiz JC, García-Hernández JL. Characterization of different Capsicum varieties by evaluation of their capsaicinoids content by high performance liquid chromatography, determination of pungency and effect of high temperature. Molecules. 2013;18(11):13471-86. doi: 10.3390/molecules181113471.PubMedUsed to support: HPLC analysis of eight Capsicum annuum varieties grown in northern Mexico: total capsaicinoids ranged from not detectable in bell pepper to 31.84 mg/g dry weight in Chiltepin; capsaicinoid content of several varieties, bell pepper included, rose when grown at high temperature.
  7. Stewart C Jr, Kang BC, Liu K, Mazourek M, Moore SL, Yoo EY, Kim BD, Paran I, Jahn MM. The Pun1 gene for pungency in pepper encodes a putative acyltransferase. Plant J. 2005;42(5):675-88. doi: 10.1111/j.1365-313X.2005.02410.x.PubMedUsed to support: Plant genetics study: the Pun1 locus, required for capsaicinoids, encodes a putative acyltransferase (AT3), and the recessive pun1 allele in every non-pungent accession tested carries a large deletion at this locus. Explains why non-pungent peppers lack capsaicin.
  8. Jensen-Jarolim E, Santner B, Leitner A, Grimm R, Scheiner O, Ebner C, Breiteneder H. Bell peppers (Capsicum annuum) express allergens (profilin, pathogenesis-related protein P23 and Bet v 1) depending on the horticultural strain. Int Arch Allergy Immunol. 1998;116(2):103-9. doi: 10.1159/000023932.PubMedUsed to support: Immunoblot study with sera from 11 patients with food allergy to bell peppers and extracts of eight horticultural strains: profilin was found in all strains and bound IgE (inhibited by birch pollen profilin), a Bet v 1 homologue was found in four strains (it bound IgE in 1 of the 11 patients), and a 23 kDa protein identical at its N terminus to the tomato osmotin-like protein P23 caused substantial IgE binding in four strains.
  9. Leitner A, Jensen-Jarolim E, Grimm R, Wüthrich B, Ebner H, Scheiner O, Kraft D, Ebner C. Allergens in pepper and paprika. Immunologic investigation of the celery-birch-mugwort-spice syndrome. Allergy. 1998;53(1):36-41. doi: 10.1111/j.1398-9995.1998.tb03771.x.PubMedUsed to support: Immunoblot study of 22 sera from patients with the mugwort-birch-celery-spice syndrome: mugwort, birch pollen and celery extracts reduced IgE binding to allergens of the spices pepper and paprika, and the 23 kDa paprika allergen was a homologue of an osmotin-like (pathogenesis-related) protein in tomato. Recombinant Bet v 1 and Bet v 2 did not inhibit binding.
  10. Takei M, Nin C, Iizuka T, Pawlikowski M, Selva MA, Chantran Y, Nakajima Y, Zheng J, Aizawa T, Ebisawa M, Sénéchal H, Poncet P. Capsicum Allergy: Involvement of Cap a 7, a New Clinically Relevant Gibberellin-Regulated Protein Cross-Reactive With Cry j 7, the Gibberellin-Regulated Protein From Japanese Cedar Pollen. Allergy Asthma Immunol Res. 2022;14(3):328-338. doi: 10.4168/aair.2022.14.3.328.PubMedUsed to support: Case study of one patient allergic to bell and chili pepper, peach, orange and Japanese cedar pollen: sensitization to Cap a 7, a newly described gibberellin-regulated protein of Capsicum annuum, cross-reactive with Cry j 7 from cedar pollen. The paper states that allergy to Capsicum is rare and that only a thaumatin-like protein and a profilin were then listed in the WHO/IUIS allergen databank.
  11. Rüger RD, Wagner S, Simon JC, Treudler R. [Severe type 1-allergy to raw bell pepper]. Hautarzt. 2010;61(4):339-42. doi: 10.1007/s00105-009-1776-3.PubMedUsed to support: Case report (German, English abstract) of a patient with anaphylaxis after eating raw bell pepper, sensitized to grass and birch pollen; the authors suggest a pollen-associated food allergy with possible Bet v 1 cross-reactivity.
  12. Suganuma H, Hirano T, Inakuma T. Amelioratory effect of dietary ingestion with red bell pepper on learning impairment in senescence-accelerated mice (SAMP8). J Nutr Sci Vitaminol (Tokyo). 1999;45(1):143-9. doi: 10.3177/jnsv.45.143.PubMedUsed to support: Animal study in senescence-accelerated mice (SAMP8): a diet containing 20% freeze-dried red bell pepper powder improved acquisition in a passive avoidance learning task compared with a standard diet. Mouse data only; not tested in people.
  13. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy: Peppers, sweet, red, raw. USDA FoodData Central. 2026;FDC ID 170108 (NDB 11821). Accessed October 2026..SourceUsed to support: Not PubMed-indexed; USDA nutrient database. Per 100 g raw sweet red pepper: vitamin C 128 mg, beta-carotene 1,620 mcg, beta-cryptoxanthin 490 mcg, lutein plus zeaxanthin 51 mcg, vitamin A 157 mcg RAE, fiber 2.1 g, energy 26 kcal (111 kJ). A medium pepper is listed at 119 g and one cup chopped at 149 g. Capsaicin is not among the listed components.
  14. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy: Peppers, sweet, green, raw. USDA FoodData Central. 2026;FDC ID 170427 (NDB 11333). Accessed October 2026..SourceUsed to support: Not PubMed-indexed; USDA nutrient database. Per 100 g raw sweet green pepper: vitamin C 80.4 mg, beta-carotene 208 mcg, beta-cryptoxanthin 7 mcg, lutein plus zeaxanthin 341 mcg, vitamin A 18 mcg RAE, fiber 1.7 g, energy 20 kcal (84 kJ).
  15. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy: Peppers, sweet, green, cooked, boiled, drained, with salt. USDA FoodData Central. 2026;FDC ID 170109 (NDB 11822). Accessed October 2026..SourceUsed to support: Not PubMed-indexed; USDA nutrient database. Per 100 g boiled, drained sweet green pepper: vitamin C 74.4 mg, beta-carotene 264 mcg, lutein plus zeaxanthin 431 mcg.
  16. WHO/IUIS Allergen Nomenclature Sub-Committee. Allergen Nomenclature database: Capsicum annuum (chili, bell pepper) allergens Cap a 1, Cap a 2 and Cap a 7. WHO/IUIS Allergen Nomenclature (allergen.org). 2026;Database entries, accessed October 2026..SourceUsed to support: Not PubMed-indexed; official allergen naming database. Lists three food allergens from Capsicum annuum (chili, bell pepper): Cap a 1, an osmotin-like (thaumatin-like) protein of 23 kDa; Cap a 2, a profilin of 14 kDa; and Cap a 7, a gibberellin-regulated protein (snakin).