Every so often we come across a food that is dynamite therapy against a host of ailments. The humble blueberry is precisely that. You may have read recently about the blueberry’s power to fight urinary tract infections and you may also be familiar with its benefits for vision. But you may not be aware that blueberries hold answers to improving memory and fighting cancer.

The blueberry is a native North American species. As such, it has always enjoyed a special place in the diets of native peoples, who introduced the fruit to European settlers. Natives enjoyed blueberries year-round. They dried the fruit in the sun, then added it to soups and stews, or ground it into powder and rubbed it into the flesh of wild game. Access to these preserved blueberry products helped settlers through their first harsh North American winters.

In folk medicine, blueberry roots were brewed for tea to help women relax during childbirth. The leaves were infused to purify the blood. Blueberry juice and syrup were also used by tribal healers to help cure coughs.

Recent scientific findings have supported this historical use and revealed some fascinating facts. For example, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University tested 40 different fruits and vegetables and found blueberries had the highest antioxidant capacity. Concord grape juice was next on the list. Grapes have about two-thirds the antioxidant strength of blueberries, followed by strawberries, kale and spinach. (Half a cup of blueberries contains the same antioxidant power as 1,000 milligrams of vitamin C.) Antioxidants neutralize damaging free radicals that contribute to cancer. They also help fight sun damage to skin.

Colour Me Healthy

The antioxidant characteristics in blueberries appear to be due largely to anthocyanins. These are the pigments that impart the blue and red colour to many fruits and flowers and are responsible for the bright red autumn foliage that we see in northern regions. Wild blueberries apparently possess one of the highest anthocyanin content of berries in North America. Their antioxidant capacity has been linked to a variety of health benefits.

A recent animal study at the Jean Mayer Center showed blueberry’s anti-aging effects. Aging animals fed diets containing blueberry extract over a two-month period lost less neurotransmitter function than those fed other diets, resulting in an improvement in navigational skills, balance, coordination and cognitive function.

Other studies have shown that the anthocyanins found in bilberry, a close relative of blueberry, are linked to reducing eye strain, controlling diabetes and improving blood circulation. The same anthocyanins in bilberry are also found in the common lowbush wild blueberry.

At the University of Illinois, researchers showed that another flavonoid constituent of wild blueberries inhibited an enzyme that acts to promote cancer. The flavonoid quercetin appears to play a role as a cardio-protective component and is reported to have potential preventive effects against certain types of tumours. Wild blueberries also contain specialized flavonoids known as proanthyocyanadins (or condensed tannins) that inhibit the promotion stage of chemically induced cancer. Wild North American blueberries were more potent than cultivated and European blueberries.

Earlier studies demonstrate the blueberry’s benefits against urinary tract infection and vision protection. Like cranberries, they inhibit bacteria from attaching to the bladder wall, thus reducing infection. Blueberries are good sources of vitamin C and fibre, with no fat, cholesterol or sodium–a truly wonderful health food.

But there is some bad news: blueberries are often pollinated by blackflies!

Buying and Storing Blueberries

Berry colour should be deep purple-blue to blue-black. Reddish berries are not ripe but are acceptable for cooking. Fresh berries should be stored covered in the fridge and washed just before use. It’s important to use berries within 10 days of harvest. The anthocyanins can quickly degrade by as much as 50 percent. Loss of antioxidant capacity also occurs with processing methods. Frozen or freeze-dried whole fruits destroy some enzymes but will preserve the anthocyanin content. Frozen fruits stored at -20°C or lower appear to retain a relatively complete complement of the phenolic and flavonoid compounds found in fresh fruit.

For freezing, arrange unwashed dry berries in a single layer on a cookie sheet. When frozen, transfer berries to a plastic bag or freezer container.

Gina Mohammed is a plant physiologist living in Sault Ste Marie, ON.

Source: alive #226, August 2001