Most of us know that blueberries are healthy – but what do we know to back up this claim? Blueberries were an important food source for Native American tribes in the east; berries, leaves and roots were also considered medicinal. In the last 10 years there has been an increasing research in compounds in blueberries that may prevent disease. Wild blueberries have been found to have a higher antioxidant capacity than cranberries, strawberries, plums, and raspberries. Here is some of the data.
The Brain: blueberries contain ‘anthocyanins’ - pigments found in red/purplish fruits and vegetables – such as purple cabbage, beets, blueberries, cocoa, cherries, raspberries and purple grapes. These pigments are antioxidant and anti-inflammatory, helping to protect brain cells and enhance their ability to signal one another. Researchers at the University of Cincinnati worked with a small group of older adults with early memory changes. Those who drank 2 cups of blueberry juice per day showed improved memory and learning, reduced depression and improved glucose levels after 3 months. Similar results have been found in experimental animals. A study from Reading University in England on people of all ages showed that people taking 200 gm (2 cups) of blueberries in a morning smoothie did better on mental tasks 5 hours later compared to people having a smoothie without blueberries. Two cups is a large (and expensive) amount of blueberries. Strawberries, cocoa and raspberries were said to have similar effects on the brain. A study at Tufts University in Boston on experimental animals showed that blueberries improved motor and navigational skills.
Cancer prevention: Studies at the University of Illinois have looked at 3 phases of cancer development – initiation, promotion and proliferation (metastasis). Various compounds in wild blueberries are helpful in prevention all 3 phases, Researchers at several universities have looked at the ability of blueberry extracts to inhibit the growth of prostate, colon, breast and cervical cancer cells. The work looks promising, but is still laboratory-based and preliminary.
Urinary Tract infections: Rutgers University has a Blueberry-Cranberry Research Center; they have found that both fruits prevent bacteria from adhering to urinary tract tissues, and this help prevent urinary tract infections. A half-cup of blueberries a day may be sufficient for this benefit.
Heart Health: A study on rats at Tufts University and the National Institute on Aging showed that when the animals had a major artery to their hearts tied off, those on a blueberry enriched diet had less damage to their hearts than those on a control diet, and were less likely to develop heart failure. Several studies in Canada and at UC Davis have shown that blueberries can reduce LDL Cholesterol (the kind that can lead to heart attack and stroke).
Diabetes: The anthocyanins in blueberries have been found to reduce blood sugar levels in rodents bred to develop diabetes, according to studies at North Carolina State University. This may mean that blueberries and their juice are safe for people with diabetes. People with high blood sugar should proceed with caution and check their levels. This may be a helpful fruit.
Blueberries and their European cousin, bilberries, are now being grown all over the world. There is said to be a blueberry juice craze in Japan, with the idea that blueberries reduce eyestrain. This has also been studied with bilberries in Europe. Most markets carry frozen blueberries all year, and fresh ones in the summer. They are a good investment.
Sadja Greenwood, MD, MPH Back issues here. Leave me a message!