Andrew Porterfield has a master’s degree in biotechnology management from the University of Maryland and has worked as a marketing communications consultant for many biotechnology and pharmaceutical firms.
While most arguments about cranberries this holiday season revolve around “berries” or “jelly,” another debate is taking place among drug-makers and researchers: what medicinal value does this little dark red, sour fruit offer?
Like many berries, cranberries possess high concentrations of polyphenols, aromatic compounds that occur naturally in the fruit mostly to ward off bacteria, fungus, and other microbes. Cranberries in particular contain significantly high levels of the polyphenol anthocyanin. A native North American plant, the cranberry fruit was long used by North American Indians to treat urinary conditions.
By themselves and even as a concentrate, cranberries are not regulated as drugs by the FDA or in Europe. But many consumers and healthcare providers, taking the cue from early North American Indians, consider the berry to be valuable for treating a wide range of disorders, from urinary tract infections (UTIs) to heart disease to cancer.
Most studies on berry-derived polyphenols have been conducted with small clinical populations, which often lack proper control groups and haven’t properly addressed ADME properties seen in large-scale drug candidate studies: absorption, distribution, metabolism, and excretion. Nonetheless, some patterns are emerging on the medicinal properties of cranberries:
• Urinary tract infection. Drinking cranberry juice is shown to help prevent UTIs in older and pregnant women, but it has not been as effective in treating existing infections. A recent study in Nutrition Journal showed that half the patients tested went six months without a UTI, a significant improvement over the control group.
• Cardiovascular disease. Some epidemiological and smaller randomized studies point to improvements in blood pressure, arterial stiffness, and lipid levels after consuming cranberries (as well as strawberries, blueberries, and concentrated extracts). However, not enough large-scale studies have been conducted to show a strong relationship. Cranberry juice, however, does enhance—perhaps harmfully so—the effects of warfarin.
• Benign prostate hyperplasia. Taking dried capsules of cranberry juice over six months appeared to lower blood levels of prostate specific antigen and reduced urine odors in people suffering from incontinence. But the same problems with these studies apply here: not enough of them and cohorts that are too small.
Assuming there is a medicinal benefit in humans, the most-documented mechanism for antimicrobe action points to the ability of pro-anthocyanins to block Escherichia coli from adhering to epithelial cells in the urinary tract. The anthocyanins appear to somehow interfere with the genetic expression of adhesion factors produced by E. coli, which enable the bacteria to attach to and invade epithelial cells. Exactly what steps of this expression are altered by anthocyanins is yet unknown, but tracking down this interaction could eventually point to the development of pharmaceuticals based on anthocyanins.
Plants have always been a valuable resource for the world’s pharmaceutical developers. While cranberries show some promise for future drugs, many questions on their effectiveness remain. Meanwhile, enjoy your holiday treats with cranberries and cranberry juice!