Nature's Bounty: The Smart of Tart

Cranberries are more than saucy; they make special claims on the brain.

By Andrea Hilbert, published September 2, 2013 - last reviewed on June 9, 2016

It was called "the waif of the swamplands," and so little was the cranberry valued that even accidental discoveries of ways to promote growth of the evergreen shrub were not exploited for commercial purposes. But that was in 1840, before growers could recite the names of antioxidants or the benefits of vitamin C or even the biological virtues of pectin. Then, in the middle of the 19th century, in the bogs of Cape Cod that are home to the tart fruit, cranberry culture took off.

Native to northern climates, and primping for harvest right about now, cranberries are botanically related to the North American blueberry and the bilberry and lingonberry of Scandinavia. They are linked nutritionally as well. All entered the 21st century as "superfoods," rich in phytochemicals and other compounds so biologically helpful they are commonly called "nutraceuticals."

"No other fruit or berry is so representative of America and all she stands for," nutritional biochemist Paul Eck enthuses, and catching sight of the bright berries that grew wild in the marshes where the Pilgrims landed just south of Cape Cod in late fall of 1620 "undoubtedly heartened" the country's first immigrants. The cranberry was not only the sole edible fruit available at that time of year; its payload of vitamin C relieved their debilitating symptoms of scurvy, a common affliction of ocean voyagers.

The 16-month growth cycle of the cranberry ends between September and November, which made it available for the very first Thanksgiving feast. The Pilgrims were introduced to the fruit by Native Americans, who ate the bitter berries raw or added maple sugar to make a sweetened sauce. Cranberries were also an essential ingredient of pemmican, a high-energy mix of deer fat and dried meat or fish that was mashed into a pulp, formed into cakes, and baked in the sun; the acidic berries not only acted as a preservative but brought nutritional balance to the mix. Green berries were pounded into a poultice for wounds and used to control fever.

But it is the deeply hued berries that are a potent source of flavonoids, a family of pigment-conferring compounds in plants that are increasingly thought to be responsible for many of the benefits associated with fruit- and vegetable-rich diets.

 Cranberry plant
Although Mediterranean cuisine is much heralded for its medicinal value, it's not the only cuisine that serves up a large helping of health. Traditional Scandinavian offerings do, too, and a notable part of the benefit comes from colorful berries. A group of Nordic researchers recently studied 70 people who followed a healthy diet rich in fish, game, and bilberries. As reported in the Journal of Internal Medicine, subjects consuming such foods showed an improved ratio of good to bad cholesterol and reduced inflammation, a process now thought to underlie many chronic conditions, including cognitive decline and heart disease.

Like blueberries, bilberries, and lingonberries,cranberries are loaded with anthocyanins, blue-red pigments that are potent antioxidants as well as powerful anti-inflammatory agents. Both properties combine to make anthocyanins important in halting age-related changes in memory and motor function. Countering inflammation maintains brain blood flow, energizing mental functions and mood while preventing hardening of the arteries. Attacking oxidative stress helps maintain the integrity of nerve cells against the ravages of time.

Today, 95 percent of the North American cranberry crop is processed, largely into beverages, most of them diluted and sweetened and of uncertain antioxidant concentration. Long a popular remedy for urinary tract infections (UTIs), with strong supportive evidence from studies, cranberry juice remains of interest as an alternative to antibiotic use, given the development of widespread bacterial resistance. In addition, new interest has focused on cranberries' potential to ward off tooth decay, gum disease, stomach ulcers, and even food-borne illnesses.

Scientists originally thought cranberries achieved their antibacterial effect by lowering the pH of the urinary tract. But recent studies suggest that a particular group of antioxidants may account for the bacteria-killing action.

Cranberries contain Type A proanthocyanidins (PACs), uniquely structured flavonoids found in few other fruits. They have been shown to reduce the ability of such notorious pathogens as E. coli to adhere to target tissues, including the bladder wall and urethra. Additional evidence suggests that Type A PACs act directly on the composition of microorganisms in the intestinal tract to reduce the number of contaminating pathogens available to do damage in the first place.

And that has scientists abuzz. "There's excitement over the growing evidence that the gut microbiota can 'talk' to our immune system, can 'talk' to our brain; that they produce, through their own metabolism and their own actions, all sorts of chemical and other mediators that affect, systemically, our whole body," says Jeffrey B. Blumberg, the director of the Antioxidants Research Laboratory at Tufts University. It's far too early in this research arena to know the full range of cranberries' effects.

Not least among the classy components of cranberries is pectin, a soluble fiber effective in transporting cholesterol out of the body, making cranberries valuable for heart health. Without pectin, cranberries would not be saucy. Pectin also gives structure to the cell walls of cranberries—and gives them "bounce," a property useful in separating good from damaged berries.

Fresh Is (Puckeringly) Best

As with most nutrient-rich foods, says Tufts's Jeffrey Blumberg, the greatest benefit comes from eating the whole food. It's possible to isolate many of the bioactive components identified in studies, such as Type A proanthocyanidins, "but the effects are likely to be much more modest than those achieved by eating the whole food." Science doesn't yet understand exactly which elements support bioactivity and how, but they do know that there are still many to be identified. "The benefits of a whole food come from the combination of many compounds working in concert," Blumberg says.

And, yes, whole cranberries and unadulterated juice are very tart. The cranberry produces an unusually small amount of sugar for a fruit, and even more tartness is conferred by flavonoids, nature's bitters—a sign the fruit is rich in bioactive compounds that go well beyond strict nutritional value.