Bromelain is a group of proteolytic (protein digesting) enzymes that are found in high concentrations in the pineapple (Ananas comosus). Bromelain is similar to the sulfhydryl proteases papain from papayas and ficin from figs. Bromelain can be obtained by eating the pineapple fruit, but commercially available supplements are usually made from the stem. Bromelain is present in the fruit to allow softening of the fruit during the ripening process. The bromelain content of various parts of the pineapple plant differs and this reflects the fact that bromelain is a collection of proteolytic enzymes not a single substance. The activity of bromelain (as with all enzymes) is expressed as enzyme units and this gives an idea of the potency of any preparation. Bromelain is bioavailable in humans and can be absorbed to the circulation when taken orally. Animal studies show that around 40 % of administered bromelain is absorbed, with peak absorption occurring 10 hour post ingestion and bromelain remaining in circulation for 48 hours.
Dietary bromelain has been researched for its ability to improve digestion, reduce inflammation, decrease blood platelet aggregation and cause relaxation of smooth muscle. The ability of bromelain to reduce inflammation is thought to occur via multiple mechanisms. In this regard, bromelain may activate proteolysis at sites of inflammation, inhibit the synthesis of proinflammatory eicosanoids, deplete kininogen (a cofactor required in the inflammatory pathway), and the activation fibrinolysis (the breakdown of fibrin in the clotting system that would normally encase the site of injury and block blood flow and cause oedema) through conversion of plasminogen to plasmin. The ability of bromelain to inhibit and reduce the inflammatory response to injury is well studies in the nutritional literature. It is the ability of bromelain to reduce inflammation that makes it useful in cases of soft tissue injury as might occur in athletes during sporting events.
The anti-inflammatory effects of bromelain make it a useful treatment for arthritis. Both rheumatoid and osteoarthritis respond positively to administration of oral bromelain, as demonstrated in clinical studies. In combination with curcumin (another potent anti-inflammatory agent) bromelain is able to reduce the requirement for corticosteroids in cases of severe arthritis. Bromelain may also be able to increase plasma and tissue levels of particular antibiotics. This may relate to the fact that bromelain itself possesses antibiotic activity and therefore potentiates the action of antibiotic drugs by providing synergism. Animal studies also suggest that bromelain has an anti-cancer activity. Interestingly when the proteolytic activity of bromelain is removed through denaturing, an anti-cancer effect in the preparation is still evident, suggesting that components other that the proteolytic enzymes within bromelain are responsible for this effect. Bromelain is taken on an empty stomach for best absorption or with food as a digestive aid.