A Review of the Dietary Intake, Bioavailability and Health Benefits of Ellagic Acid (EA) with a Primary Focus on Its Anti-Cancer Properties

Ellagitannins (ET) and ellagic acid (EA) are polyphenols, present in common foods, which may exhibit significant health benefits against inflammation, infection and cancer. EA is metabolised by the gut flora to produce urolithins, which are absorbed into the systemic circulation. Urolithins are widely documented to reduce oxidative stress associated with many diseases including cancer, heart disease and liver damage. In particular, Urolithin C and D have been shown to have high anti-oxidant properties through the inhibition of reactive oxygen species (ROS). The anti-inflammatory properties of EA have been demonstrated through the down-regulation of pro-inflammatory enzymes such as COX-2 and iNOS as well as decreasing the expression of adhesion molecules. EA also regulates the gut microflora and possesses antimicrobial activity against various strains of harmful bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and Helicobacter pylori. Numerous studies have documented the anticarcinogenic benefits of EA and have been performed on, but not limited to, prostate, colon and breast cancer cell lines and in vivo models. Conventional treatments for cancer, such as chemotherapy, can often be associated with significant side effects such as fatigue, hair loss and alopecia. Naturally-occurring food substances such as ETs potentially offer a risk-free preventative measure against cancer and could perhaps be used in synergy with current treatments. More level 1 studies are required to inform the evidence-base on this topic.