The fruits of Rubus are one of the most concentrated sources of dietary ellagitannins, on average higher than 1000 mg/kg. [4] The trimeric lambertianin C and the dimerics sanguiin H-6 are by far the major ellagitannins of Rubus berries. Lambertianin C is the major ellagitannin in blackberries and sanguiin H-6 in raspberries.[4] Besides these two compounds, another 20 minor ET were recently detected and preliminarily characterized in Rubus extracts.[4]
Ellagitannins are polyphenolic antioxidants formed from ellagic acid and a carbohydrate (often times glucose). Abundant in fruits, seeds, and nuts, ellagitannins are thought to have many protective properties on health, chief among them being potential their anti-cancer properties. The question for us is: do the claims hold up under scrutiny, and if so, what are the best sources of ellagitannins?
Research on ellagitannins has focused heavily on their anticancer and antimicrobial properties. Thought to be naturally occurring insecticides, ellagitannins are found in high concentrations in raspberries, blackberries, acai berries, pecans and walnuts. Studies have shown that the main metabolite of ellagitannin, (ellagic acid), may be an effective anticancer agent. Of particular interest is its potential at preventing cancers of the cervix, colon, prostate, breast, esophagus, and skin.
The excitement about ellagitannins, and more specifically, their metabolite ellagic acid, is the reason acai berries, raspberries, and pomegranates have garnered their reputation of superfruits. It has also spawned a host of claims about the cancer-fighting capacity of these foods, which have yet to be substantiated by solid science. Some of these claims have been rather outlandish, and prompted the FDA to issue warning letters in 2007 and 2008 against companies making unsubstantiated claims.
