Capers are the flower buds of a shrub native to the Mediterranean and Middle East and are usually pickled before being eaten or used as condiments. The most important phytochemicals present in capers are isothiocyanates, which are similar to those found in other spices of the brassica family: mustard, horseradish and wasabi. The isothiocyanates in brassicas have been found to have strong anticancer properties and, although the use of capers in preventing cancer has yet to be investigated, this spice is likely to exhibit similar effects. Contemporary research into the healing properties of capers has, however, focused principally on its use as a lipid-lowering and antidiabetic agent.

Important Phytochemicals

Antioxidants: Beta-sitosterol, beta-sitosterol-glucoside, quercetin, rutin, vitamin E
Others: Coumarin, glucosinolates, isothiocyanates

Medicinal Properties

Cardiovascular Disease and Blood Lipids
Capers have shown strong blood lipid-lowering activity in individuals with abnormally high lipid levels. Only four days after beginning a regular dose of capers, blood cholesterol and triglyceride levels start to fall. After two weeks of this treatment, they have dropped considerably and often reach normal levels in some individuals.  

Diabetes
Abnormally high glucose levels in diabetics begin to fall after only one day of taking a caper extract, and after two weeks most patients have normal blood glucose levels. The exact mechanism of caper’s glucose-lowering effect has not yet been established, but insulin levels stayed the same for the duration of the studies so their action is unlikely to be due to the stimulation of insulin release from the pancreas. As is the case with so many of the other antidiabetic spices, capers probably work by increasing the sensitivity of the cells’ insulin receptors or by mimicking the effect of insulin on the receptors themselves. Interestingly, capers do not affect the blood sugar levels of non-diabetics.