Currants are small sour berries that are normally eaten in dried form (resembling small raisins) or as jam in the U.S. Black currants (Ribes nigrum), red currents, and white currants are the most common varieties. Currants, which are related to gooseberries (Ribes uva-crispa), are good sources of vitamin C and have been shown to have antioxidant and anti-inflammatory properties. Darker varieties are rich sources of anthocyanins (including cyanidin-3-glucoside and delphinidin), which have been reported to have anticancer properties. Currants also contain quercetin, myricetin, and ellagic acid. Currant roots and seeds are high in gamma-linolenic acid (GLA), which has been traditionally used to treat pre-menstrual syndrome and other "female" health problems.
Breast cancer-related effects of eating currants
Currants share many of the properties of blueberries and cranberries and therefore would be expected to have similar chemopreventive effects against breast cancer. For example, delphinidin, an anthocyanin found in black currants, has been shown to block epidermal growth factor receptor (EGFR) signaling in breast cancer cells. (EGFR, which is expressed at high levels in at least 30% of breast cancers, is associated with a poor prognosis.) Delphinidin was shown to induce apoptosis (programmed cell death) in HER2+ breast cancer cells in another study.
Quercetin has been shown to increase the effectveness of both Adriamycin (doxorubicin) and Taxol (paclitaxel) chemotherapy in multidrug resistant ER+/PR+ breast cancer cells, in part by eliminating cancer stem cells.
In addition, black currant compound cyandin-3-glucoside has been shown to possess both chemopreventive and chemotherapeutic activity and to enhance the treatment effects of Herceptin. However, the few population studies that have been undertaken which have included currants have not attempted to isolate the effects of this berry.
Black currant seed oil, evening primrose oil, and borage oil are all marketed as sources of GLA. GLA is an omega-6 unsaturated fatty acid with anti-inflammatory properties (unlike the omega-6 fatty acids in vegetable oils, which tend to be pro-inflammatory). GLA and its metabolites affect the expression of various genes, including ones that play a significant role in immune functions and cell death. Most people obtain abundant levels of GLA through their diets (GLA is produced in the body from linoleic acid) and do not need supplementation. Black currant oil, evening primrose oil, and borage oil have numerous biologically active components (such as flavonols and phenolic acids) in addition to GLA and their health-related effects may be the result of these other components.
Consumers should be aware that, like cranberry juice, currant juice may have high levels of sugar or other sweeteners.
Below are links to recent studies concerning this food. For a more complete list, including less recent studies, please click on currants.