The Straight Story On Ellagic Acid

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.  Their metabolite, ellagic acid, is formed during digestion, and a number of benefits to ellagic acid are being cited in the media.  The question for us is:  do the claims hold up under scrutiny, and if so, what are the best sources of ellagitannins?

Ellagic Acid

Research on ellagic acid 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 Truth About Ellagic Acid

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.

When consumed, ellagitannins are rapidly metabolized to form ellagic acid and the complementary carbohydrates.  Researchers have found that when a variety of cancer cells are exposed to ellagic acid in a test tube, the ellagic acid disrupts the life cycle of cancer cells, usually by promoting cell death.  Unfortunately, there are no guarantees that this activity translates from the test tube to the human body.  Furthermore, ellagic acid is a relatively insoluble compound, and there’s some evidence that indicates it may not be “bio-available.”

By contrast, ellagitannins (the parent compounds) are readily water-soluble, and researchers believe they may be more easily metabolized by the body, making them an excellent source for “delivering” ellagic acid to the body.  This difference leads naturally to the conclusion that ellagic acid, consumed in the form of acid supplements, may be less effective than eating “real food.”  Unfortunately, although at least one study has shown ellagitannins may help reduce prostate-specific antigen (PSA) levels, there appears to be very little research in human trials to support some of these claims being made by supplement manufacturers.

With all the caveats, there’s no disputing the fact that there’s “consistent epidemiological evidence” linking a diet rich in fruits and vegetables with reduced incidence of cancer and coronary disease.  And there’s little doubt that even beyond the possible benefits of ellagitannins, choosing a diet rich in fruits and vegetables has a wide array of potential health benefits, so if you’re so inclined to increase your consumption of antioxidants, the following table lists the ellagitannin content of some commonly available foods.

Food Sources Of Ellagitannin

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