Pineapple, a fruit with unexpected healing properties

Initial note: This article was previously published and is republished here in an updated form according to scientific and divulgative criteria. The purpose is informative: it does not replace medical advice. For therapeutic decisions or diagnoses, consult your healthcare professional.

In brief

• Pineapple contains bromelain, an enzymatic extract with proteolytic activity studied for anti-inflammatory, digestive, and immunomodulatory effects.
• Bromelain shows biological activity in vitro and in vivo; some clinical studies suggest benefits in inflammatory and painful conditions, but the quality of evidence is variable.
• Consuming pineapple can temporarily increase plasma melatonin levels, but clinical effects on sleep remain modestly documented.
• Bromelain can interfere with coagulation and the absorption of some medications; it should be considered with caution in people taking anticoagulants or specific therapies.

Abstract: what does science say?

Pineapple (Ananas comosus) is a natural source of the enzymatic mixture called bromelain, found mainly in the stem and non-edible parts of the fruit. Experimental and clinical literature indicates that extracts containing bromelain have anti-inflammatory, proteolytic, and modulating effects on certain immune and coagulation pathways. Some clinical trials of variable quality suggest symptomatic benefits (for example, in osteoarthritis and after dental extractions), while preclinical studies indicate potential actions on intestinal inflammation, fibrinolysis, and antitumor activity in experimental models. Pineapple consumption increases serum melatonin in the short term. However, the strength of the conclusions depends on the form (fruit, juice, standardized extract), dose, duration, and methodological quality of the studies: much evidence remains observational or preclinical and does not establish definitive causal relationships.

Biological mechanisms and active components

Bromelain: composition and proteolytic action

Bromelain is a complex of proteolytic enzymes extracted from the pineapple plant; commercial preparations contain fractions with different compositions (stem vs fruit bromelain). In the laboratory, bromelain breaks down proteins and modulates inflammation mediators; reductions in some pro-inflammatory cytokines and alterations in pathways such as NF-κB and MAPK have been reported. A recent review summarizes multiple biological activities attributed to bromelain, including anti-inflammatory, immunomodulatory properties, and possible effects on coagulation and fibrinolysis [1].

Absorption and bioavailability: what we know

Experimental studies and reviews indicate that portions of bromelain can be absorbed orally in active form or as functional fragments and reach systemic circulation, although the absorbed amount and its stability depend on the formulation (e.g., gastro-resistant capsules, purified extracts) and gastric status. Variability between preparations and administration protocols limits direct comparisons between studies [2].

Other components: melatonin and phytochemicals

Pineapple also contains small amounts of melatonin and other bioactive compounds (phenols, flavonoids) that can contribute to temporarily increasing the blood's antioxidant capacity after fruit consumption. The biological role of these quantities is plausible, but the translation into lasting clinical effects requires further confirmation [6][7].

Clinical evidence and observed applications

Pain and osteoarthritis

Several clinical studies and enzymatic preparations containing bromelain or enzymatic combinations have shown improvements in joint symptoms and physical function compared to baseline or active treatments in some trials. A 16-week randomized trial reported WOMAC improvement after bromelain treatment in patients with knee osteoarthritis [4]. Other experiments with enzymatic combinations (e.g., Wobenzym) have shown pain reductions in some contexts, but the overall picture requires larger, well-controlled studies [5].

Respiratory tract and sinusitis

Older clinical studies and reviews suggest a possible role for bromelain as supportive therapy in upper respiratory tract conditions, including reducing edema and mucus in acute or chronic sinusitis. Some pediatric trials and case-control studies have reported improvements in respiratory symptoms, but the quality and methodological heterogeneity make interpretation cautious [8].

Intestinal inflammation and gastrointestinal diseases

Preclinical results indicate that bromelain can modulate the inflammatory response in the intestinal mucosa and improve histological parameters in murine models of colitis; recent controlled clinical studies suggest that supplementation can reduce clinical activity in patients with mild-to-moderate ulcerative colitis, although the data are still preliminary and require independent confirmation [8][9].

Coagulation, fibrinolysis, and drug interactions

In vitro studies and some clinical experiments indicate that bromelain can modulate coagulation and platelet aggregation: data from thromboelastography tracings have shown alterations in coagulability in the presence of bromelain ex vivo, suggesting potential anticoagulant effects at certain concentrations [3]. For this reason, caution is advisable in subjects taking anticoagulants or with bleeding disorders.

What it means in practice

For the public: pineapple is a nutritious food with interesting bioactive compounds. Eating pineapple as part of a varied diet can contribute to the intake of fiber, vitamins, and minerals; fruit consumption can also temporarily increase certain antioxidant or melatonin markers in the blood. Standardized bromelain extracts, used as supplements, have shown symptomatic effects in some studies (for example, on joint pain, post-operative swelling, or inflammatory disorders), but they are not a substitute therapy for chronic or serious conditions. If considering bromelain-based supplements, it is advisable to discuss it with your doctor, especially if you are taking anticoagulants, antiplatelet drugs, or medications that may interact with intestinal absorption.

Key points to remember

• Bromelain is an enzymatic mixture with proteolytic activity and numerous biological effects documented in the laboratory and in some clinical trials [1][2].
• Some clinical studies show symptomatic benefits (e.g., joints, post-operative), but the strength of the evidence is variable and not always conclusive [4][5].
• Consuming pineapple increases serum melatonin in the short term; effects on sleep or long-term health are not defined [6][7].
• Possible interactions with coagulation and some medications: caution in people on anticoagulant therapies or with bleeding problems [3].
• The form of intake (fruit, juice, standardized extract) affects dose and bioavailability; results are not automatically transferable from one to another.

Limitations of evidence

It is important to distinguish between types of studies. Many claims derive from preclinical data (in vitro or in animal models) or observational studies; these suggest biological plausibility but do not prove causality in humans. Some randomized clinical trials exist, but they are often small, of limited duration, or use combined preparations (e.g., enzymatic mixtures) that prevent isolating the effect of bromelain alone. Common methodological limitations include small samples, heterogeneity of doses and formulations, absence of robust biological endpoints, or prolonged follow-up. In contexts where the effect is plausible (for example, local inflammation), large-scale studies are needed, with well-defined doses and products, clinical endpoints, and systematically evaluated safety.

Editorial conclusion

Pineapple and bromelain represent an example of how a traditional food can provide molecules with potential therapeutic interest. Research has gathered evidence supporting various biological activities of bromelain, and some clinical studies suggest benefits in selected situations. However, robust translation into clinical recommendations requires further controlled trials and standardization of preparations. Meanwhile, consuming fresh pineapple is reasonable as part of a balanced diet; the use of bromelain-based supplements requires individual evaluation and discussion with a doctor, especially in the presence of concomitant therapies.

Editorial note

This text updates a previously published article. The update was carried out following criteria of scientific accuracy, divulgative clarity, and transparency of sources. The content is for informational purposes: it does not replace specialized medical advice.

Scientific research

Below are the scientific references cited in the text. DOIs are verified and clickable for consultation.

1. Hikisz P, Bernasińska‑Słomczewska J. Beneficial Properties of Bromelain. Nutrients. 2021;13:4313. https://doi.org/10.3390/nu13124313
2. Pavan R, Jain S, Shraddha, Kumar A. Properties and Therapeutic Application of Bromelain: A Review. Biotechnol Res Int. 2012;2012:976203. https://doi.org/10.1155/2012/976203
3. Kaur H, Corscadden K, Lott C, Elbatarny HS, Othman M. Bromelain has paradoxical effects on blood coagulability: a study using thromboelastography. Blood Coagulation & Fibrinolysis. 2016;27(7):745‑752. https://doi.org/10.1097/MBC.0000000000000244
4. Kasemsuk T, Saengpetch N, Sibmooh N, Unchern S. Improved WOMAC score following 16‑week treatment with bromelain for knee osteoarthritis. Clin Rheumatol. 2016;35:2531‑2540. https://doi.org/10.1007/s10067-016-3363-1
5. Bolten W et al. The Safety and Efficacy of an Enzyme Combination in Managing Knee Osteoarthritis Pain in Adults: A Randomized, Double‑Blind, Placebo‑Controlled Trial. Arthritis. 2015: Article ID 251521. https://doi.org/10.1155/2015/251521
6. Sae‑Teaw M, Johns J, Johns NP, Subongkot S. Serum melatonin levels and antioxidant capacities after consumption of pineapple, orange, or banana by healthy male volunteers. J Pineal Res. 2013;55(1):58‑64. https://doi.org/10.1111/jpi.12025
7. Johns NP, Sae‑Teaw M, Porasuphatana S, Plaimee P. Dietary intake of melatonin from tropical fruit altered urinary excretion of 6‑sulfatoxymelatonin in healthy volunteers. J Agric Food Chem. 2013;61(4):913‑919. https://doi.org/10.1021/jf300359a
8. Delgarm P, Mokhtare M, Ebrahimi Daryani N, et al. Effects of bromelain supplementation on disease activity and quality of life in patients with ulcerative colitis: a randomized, triple‑blind, placebo‑controlled study. Sci Rep. 2025;15:42799. https://doi.org/10.1038/s41598-025-26975-1
9. Varilla C, Marcone M, Paiva L, Baptista J. Bromelain, a Group of Pineapple Proteolytic Complex Enzymes (Ananas comosus) and Their Possible Therapeutic and Clinical Effects. Foods. 2021;10:2249. https://doi.org/10.3390/foods10102249

Note: if some topics cited here require more detail (e.g., precise dosages used in trials or commercial characteristics of preparations), specific placeholders are present: [details of dosages and formulations in individual trials] and can be added upon request.