Bromelain is the name for the protease enzymes extracted from the stem and fruit of fresh pineapple. The commercial supplement is usually obtained only from the stem of the pineapple, which contains a higher concentration of the enzymes than the fruit.
Bromelains are sulphydryl proteolytic enzymes, including several proteases. In addition, bromelain also contains small amounts of non-proteolytic enzymes (including acid phosphatase, peroxidase and cellulase), polypeptide protease inhibitors and organically bound calcium.
Bromelain is an anti-inﬂammatory agent and is thought to act through direct or indirect effects on inﬂammatory mediators. It inhibits the enzyme thromboxane synthetase, which converts prostaglandin H2 into proinﬂammatory prostaglandins and thromboxanes. Bromelain also stimulates the breakdown of ﬁbrin, which stimulates pro-inﬂammatory prostaglandins responsible for ﬂuid retention and clot formation. It also appears to promote the conversion of plasminogen to plasmin, causing an increase in ﬁbrinolysis.
Various claims are made for the value of bromelain supplementation, but much of the research underpinning these claims was carried out in the 1960s and 1970s, and there are very few well-controlled human studies.
Bromelain has been associated with improvement in symptoms of sinusitis, acceleration of wound healing, potentiation of antibiotic action, healing of gastric ulcers, treatment of inﬂammation and soft tissue injuries, reduction in severity of angina, reduction in sputum production in patients with chronic bronchitis and pneumonia and decrease in symptoms of thrombophlebitis.
Two double-blind, placebo-controlled studies showed that bromelain 160mg (400000 units) could reduce some symptoms of sinusitis. However, headache was not improved in either study.
In a double-blind,placebo-controlled trial, 146 boxers with bruises to the face and haematomas to the eyes, lips, ears, arms and chest received either 160mg bromelain daily or placebo for 14 days. At day 4, 78% of the bromelain-treated group were completely cured of their bruises compared with 15% of the placebo group. However,this result was not tested for statistical signiﬁcance. A randomised,double-blind trial in 40 subjects with muscle soreness as a result of exercise compared the outcomes with ingestion of either ibuprofen or bromelain. There was no difference between treatments.
There is preliminary clinical evidence that the anti-inﬂammatory and analgesic properties of bromelain help to reduce symptoms of osteo and rheumatoid arthritis. In a controlled trial involving 77 subjects suffering from mild knee pain, ingestion of bromelain (200 and 400 mg) resulted in improvements in total symptoms, stiffness and physical function in a dose dependent manner. The authors concluded that double-blind, placebo-controlled studies are now warranted to conﬁrm these results.
Bromelain has been reported in at least two studies to reduce the degree and duration of swelling and oral pain with oral surgery. However, one study was not controlled and the other had no statistical analysis.
Bromelain could be useful as an anti-diarrhoeal agent. In an in vitro study,9 bromelain was shown to prevent intestinal ﬂuid secretion mediated by Escherichia coli and Vibrio cholerae, and in other studies to protect piglets from diarrhoea. However, there are no human studies to date.
Bromelain has been reported to reduce the severity of angina, and several in vitro studies have demonstrated that bromelain reduces platelet aggregation.
Ulcerative colitis A letter from two US consultants stated that two patients with ulcerative colitis achieved complete clinical and endoscopic remission after initiation of therapy with bromelain.
Cystitis One double-blind study in humans revealed that bromelain was effective in treating noninfectious cystitis.
No problems have been reported, but based on the potential pharmacological activity of bromelain, i.e. that it may inhibit platelet aggregation, bromelain should be used with caution in patients with a history of bleeding or haemostatic disorders.
Pregnancy and breast-feeding Noproblemshavebeenreported,buttherehave been insufﬁcient studies to guarantee the safety of bromelain in pregnancy and breast-feeding.
None reported, but there are no long-term studies assessing the safety of bromelain.
None reported, but theoretically, bleeding tendency may be increased with anticoagulants, aspirin and antiplatelet drugs.
Bromelain is available in the form of tablets, capsules and powders.A variety of designations have been used indicate the activity of bromelain. These include rorer units (ru), gelatin dissolving units (gdu) and milk clotting units (mcu). One gram of bromelain standardised to 2000 mcu would be approximately equal to 1 gram with 1200gdu of activity or 8g with 100000ru activity. The dose is not established. Dietary supplements provide 125–500 mg in a dose.
Many claims have been made for bromelain, based largely on studies conducted in the 1960s and 1970s. Many of the published trials are uncontrolled human studies or animal or in vitro studies, and well-controlled clinical trials are required to establish the role of bromelain as a potential supplement.
(extracted from) Dietary Supplements, Third Edition, by Pamela Mason, BSc, MSc, PhD, MRPharmS, published by Pharmaceutical Press, London, 2007.