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Blueberries and Health
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Lin Yan

The blueberry, named for its velvety, deep-blue color, is one of the few fruits native to North America.  Native Americans used the berries, leaves and roots for medicine and used the fruit as a fabric dye.  Blueberries originally are found in the wild, and now they can grow in many regions of the United States.  Most cultivated varieties are grown in Michigan, North Carolina, Georgia, California and the Northwest.  Wild blueberries, also known as lowbush blueberries, are abundant in Maine and Eastern Canada.  Wild blueberry is the official fruit of Maine.

Blueberries are an excellent source of essential nutrients, such as vitamins C and K and manganese, and a good source of dietary fiber.  In addition, blueberries are abundant of phyto-components, such as flavonoids, which are responsible for berries' antioxidant and anti-inflammatory activities. 

Wild blueberries are rich in antioxidants.  One serving of wild blueberries has more total antioxidant capacity than one serving of cranberries, strawberries, plums or others.  Oxidative stress is linked to aging, heart diseases and cancer.   

In human studies, researchers showed that blueberries are highly beneficial in maintaining memory function and preventing congnitive degeneration.  One study conducted at University of Cincinnati found that consumption of blueberry-supplemented diets improved memory function and mood in older adults with early memory decline, and it suggested that regular consumption of blueberries may slow the loss of congnitive function and decrease depression in elderly.  The other at Harvard Medical School showed that eating one or more servings of blueberries each week may help slow congnitive degeneration by several years in women.  These observations are supported by laboratory studies that showed a diet of blueberries improves motor skills and reverses short-term memory loss, and it may be possible to overcome genetic predispositions of Alzheimer disease through the diet. 

A growing body of research points to the potential for a blueberry-enriched diet to promote heart health.  A team at Harvard School of Public Health reported that eating berries such as blueberries appear to reduce the risk of heart attack in women by 33%.  Atherosclerosis is the build-up of plaques in arteries starting as fatty streaks where cholesterol accumulates.  Blueberry-fed animals develop fewer plaques in aorta than in controls, and thus reduce the risk of cardiovascular diseases.  Furthermore, blueberries may support heart health through cholesterol lowering effects. 

High blood pressure is the second leading cause of end-stage kidney disease in the U.S., and it is a growing problem with the aging and overweight populations. Laboratory studies revealed that wild blueberries could help regulate blood pressure and have the potential to decrease the vulnerability of heart blood vessels to oxidative stress and inflammation. 

Metabolic syndrome is a combination of medical disorders including high blood pressure, high cholesterol, obesity, and impaired glucose tolerance, which is responsible for increased risk of diabetes and cardiovascular diseases.  Daily consumption of whole blueberries help people with type 2 diabetes reduce that risk by increasing participants' insulin sensitivity, a key determining factor in preventing type 2 diabetes.  Furthermore, extracts from blueberries help alleviate hyperglycemia in laboratory animals, a condition that is associated with diabetes and metabolic syndrome.

Blueberries may promote certain intestinal bacteria that are beneficial to digestive health and the immune system.  Available clinical studies show that regular consumption of a wild blueberry drink favorably affects the composition of the intestinal microbiota by increasing a type of beneficial bacteria called Bifidobecteria.       

Blueberries contain numerous nutrients and phyto-components, many of which have been well studied for their roles in cancer prevention.  For example, dietary fiber can act in several ways to lower cancer risk, including helping with weight control.  Excess body fat increases the risk of several different cancers, and dietary fiber can increase the feeling of fullness.

Laboratory research is extensive on blueberry phyto-components such as flavonoids.  In animal studies, blueberries decrease pre-cancerous changes and inflammation in colon and decrease estrogen-induced mammary cancer and DNA damage.  In cell studies, blueberry extract and its purified flavonoids decrease free radical damage to DNA that can lead to cancer.  They also decrease growth and increase self-destruction of lung, breast, colon and prostate cancer cells.

Blueberries are readily from the market.  Choose firm, plump, dry blueberries with dusty blue color.  Avoid berries that are soft, shriveled or with any sign of mold.  Buy frozen blueberries too.  They are also high in nutrients and antioxidant phyto-components.  In the kitchen, whirl blueberries alone or with other fruits into a smoothie or fruit freeze drink, top cereal or yogurt with fresh or dried blueberries, or add them to a green salad. Blueberries play well with other fruits alone or in combination, enjoy them in muffins, pancakes, fruit crumble or crisp desserts.