Blueberries contain a potent antioxidant that may help prevent colon cancer, without the side effects of some cancer-fighting drugs, researchers say. (March 24, 2007)

The health halo that crowns berries — the original "superfruit" — hasn't slipped a bit over the years. Ever since it was discovered that berries have very high total antioxidant capacity, the public has had a veritable love fest for berries, making them its favorite fruit.

Over the past decade, multiple research findings have supported the health benefits of berries, showing that they have a profound impact on chronic diseases, such as cancer, cardiovascular disease, diabetes and age-related mental decline.

In botanical terms, a berry is a fleshy fruit in which the entire plant ovary wall ripens into a soft fruit surrounding seeds. Thus the definition of berries extends to include fruits like tomatoes, grapes and avocados. But in common terms, "berries" refers to the small fruits with multiple seeds we are familiar with today. While exotic berries such as acai have gleaned a lot of public attention, the largest body of berry research focuses on the traditional berries available in North America — blackberries, black raspberries, blueberries, cranberries, red raspberries and strawberries.

Berries have been an important part of culinary traditions — from preserving berries to pressing them for juice — that stretch across many cultures and date back centuries. Could it be that berries offer particular benefits for humans that extend beyond just a delicious food?

Berries are low in calories, sodium and fat, and high in fiber, potassium and vitamin C. This profile makes them a perfect food for supporting heart health, normal blood pressure and weight loss. But that's not all, according to Navindra Seeram, assistant professor in the Bioactive Botanical Research Laboratory at the University of Rhode Island.

"Berries are really packed with antioxidants," Seeram said. "Plants put their best compounds on their outer layers and in seeds. A plant can't get up and put sunscreen on to protect itself from environmental damage. You eat it all with berries — they are loaded with skins and seeds, and you don't even realize it."

Scientists are trying to determine which bioactive ingredients are responsible for berry benefits. Researchers from Finland's National Institute for Health and Welfare studied the bioavailability of berry compounds and found that polyphenols are the most likely compounds responsible for heart health benefits.

Within the class of polyphenols, there are flavonoids such as anthocyanins, and procyanidins and ellagitannins, Seeram said. These compounds appear to be at the root of the protective effects of berries. Bioavailability is the buzz word. These days, just about every plant food has bragged about being on the high ORAC (oxygen radical absorbance capacity, a measure of antioxidant capacity) list. But many scientists don't put a lot of faith in ORAC values alone.

"It's a common marketing ploy to talk about how much antioxidant potential a food has, but it's misleading," Seeram said. "These are lab-based tests; we don't know if it means anything in the body. The focus of research has moved away from total antioxidant capacity to what happens in live systems."

Scientists are trying to determine what happens to these bioactive compounds when they are eaten. What gets into the blood and tissues? What happens when the liver enzymes and the gut microflora go to work on them?

According to Paul Milbury, Ph.D., assistant professor at Tufts University, it is becoming clear that berry anthocyanins can penetrate the blood brain barrier in rodents and can also be found in the brain and eye tissues of pigs after blueberry feeding. And Spanish researchers recently reported that metabolites of berry ellagitannins reach and enter the human prostate after consumption of ellagitannin-rich foods like berries. These findings give scientists a clue that after berries are consumed, some compounds are absorbed into body tissues, rather than being excreted by the body.

Scientists can trace several ways that berries can mediate disease, such as targeting oxidative stress, inflammation, immune function and metabolism. "Berry compounds work on multiple mechanisms in the body. They are hitting the pro-inflammatory processes and the central pathways linked with diseases like cancer, cardiovascular disease and Alzheimer's disease," Seeram said.

While scientists continue to learn more about how berry compounds work in humans, Seeram said there are some facts you can take to the bank.

"Berries are healthy. Cranberries can prevent urinary tract infections, blueberries are important in brain health and berry compounds target pro-inflammatory pathways."

Another fact you can take to the bank? Berries are delicious. Try fitting them into your diet every day.

From Environmental Nutrition newsletter; environmentalnutrition.com. Distributed by Tribune Media Services.