The blueberry is the fruit of a shrub that belongs to the heath family. Blueberries grow in clusters and sizes vary from that of a pea to a marble. Color ranges from blue to maroon to purple-black. The blueberry season runs from May through October. Blueberries are native to North America where they grow throughout the woods and mountainous regions in the United States and Canada.
There are about 30 different varieties of blueberry, each growing in a different region of North America. The highbush blueberry is common to the eastern Seaboard. The lowbush variety is common to the Northeast and eastern Canada and the Evergreen blueberry can be found in the Pacific Northwest. North America is the world’s leading blueberry producer, accounting for nearly 90% of world production.
The common blueberry is an abundant source of several potent antioxidants, particularly Anthocyanin and related compounds. Clinical studies have shown that Anthocyanin neutralizes free radicals which are specific to age-related mental clarity and memory capacity.
This particular family of antioxidants has also been proven effective in fighting the free radicals responsible for macular degeneration and other age-related eye disorders.
In fact, a 2001 study at Tufts University rated Blueberries as the most potent antioxidant of over 60 foods tested (Tufts University. Researching a Blueberry/Brain Power Connection. Tufts University Health and Nutrition Letter, March 2001, Vol. 19. Number 1).
A close relative of the blueberry, the bilberry also contains a similar family of antioxidants. The bilberry is a specifically potent source of Anthocyanidin, which is noted for strengthening of the capillaries of the eye. Bilberry is already widely noted for slowing of age-related macular degeneration, night blindness, and diabetes-related eye disorders.
The Amazing Blueberry Benefits
Blueberries are powerful antioxidants. Antioxidants help neutralize harmful by-products of metabolism called “free radicals” that can lead to cancer and other age related diseases. Anthocyanin, which is the pigment that makes the blueberry blue, is the key antioxidant responsible for these benefits (Prior, RL, et. al. J of Agric. Food Chem. 1998, 46:2686-2693).
Blueberries are believed to reduce the build-up of bad cholesterol that is a contributor to cardiovascular disease and stroke, due to their antioxidant effects (Heinenen, L.M. et al. J. Agric. Food Chem. 1998, 46:4107-4112). A diet that features blueberries may also improve motor skills and reverse the short term memory loss associated with such age-related diseases as amyotrophic lateral sclerosis, Alzheimer’s disease, and Parkinson’s disease (Nutritional Neuroscience, 6:153-162, 2003; Journal of Neuroscience, September 15, 1999, 19(18); 8114-8121).
In vitro research carried out in 2001 at the University of Mississippi found that blueberry extracts slowed the growth of two aggressive cervical cancer lines and two fast-replicating breast cancer cell lines (Wedge DE, Meepagala KM, Magee JB, et al. Anticarcinogenic Activity of Strawberry, Blueberry, and Raspberry Extracts to Breast and Cervical Cancer Cells. J Med Food. 2001;4(1):49-51).
A 2005 study at the University of Georgia demonstrated blueberry extract’s ability to inhibit cell proliferation in two separate lines of colon cancer cells, reducing by more than 50% the rate at which the cells otherwise multiplied.
Researchers concluded that phenolic compounds in blueberries can inhibit colon cancer cell proliferation and bring on apoptosis (programmed cell death) (Yi W, Fischer J, Krewer G, Akoh CC. Phenolic compounds from blueberries can inhibit colon cancer cell proliferation and induce apoptosis. J Agric Food Chem. 2005 Sep 7;53(18):7320-9).
Cancerous cells are able to grow and invade surrounding tissue by secreting enzymes that break down the surrounding matrix that would otherwise confine them. A study published in August 2005 in the Journal of Nutritional Biochemistry showed that blueberry flavonoids down-regulate these structure-degrading enzymes that enables cancerous cells to spread and invade other tissues.
(Matchett MD, Mackinnon SL, Sweeney MI, et al. Inhibition of matrix metalloproteinase activity in DU145 human prostate cancer cells by flavonoids from lowbush blueberry (Vaccinium angustifolum) : possible roles for protein kinase C and mitogen-activated protein-kinase-mediated events. Nutr Biochem. 2005 Aug 17 (Epub ahead of print).
Blueberries contain another antioxidant compound called ellagic acid, which blocks metabolic pathways that can lead to cancer (Ahn. D. et al. The effects of dietary ellagic acid on rat hepatic and esophageal mucosal cytochromes P450 and phase II enzymes. Carcinogenesis 1996 Apr;17(4):821-8).
Effect on Brain
In vitro research involving rats has demonstrated that blueberries have the ability to enhance dopamine levels. Dopamine is an essential neurotransmitter that enables smooth, controlled movements as well as efficient memory, attention, and problem-solving function.
Researchers also believe that blueberry extract might increase brain cell membrane fluidity while reducing levels of inflammatory compounds, thus slowing the brain’s normal aging process (Joseph JA, Shukitt-Hale B, Denisova NA, et al. Reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation. J Neurosci. 1999 Sep 15;19(18):8114-21).
In a 2004 study, the spatial memory of laboratory animals was enhanced by the addition of blueberries to their diet. When later studied in vitro, the animals’ brains demonstrated structural changes associated with an improved capacity for learning (Casadesus G, Shukitt-Hale B, Stellwagen HM, et al. Modulation of hippocampal plasticity and cognitive behavior by short-term blueberry supplementation in aged rats. Nutr Neurosci. 2004 Oct-Dec;7(5-6):309-16).
Effect on Urinary Tract
A compound found in blueberries promotes urinary tract health and reduces the risk of infection. It does this by preventing bacteria from adhering to the cells that line the walls of the urinary tract (Ames BN, Shigenaga MK, Hagen TM. Oxidants antioxidants, and the degenerative diseases of aging. Proc. Natl. Acid. Sci. USA 90:7915-7922, 1993.
Effect on Eyesight
A number of studies have shown that blueberries and bilberries (the European cousin of the blueberry) improve eyesight. Blueberries prevent eye damage, preserve eyesight and are helpful in treating myopia (nearsightedness).
Blueberry consumption may offer a great deal of protection against retinal degeneration (particularly diabetic retinopathy and diabetic cataracts). Blueberries may also offer significant protection against the development of glaucoma because of its collagen enhancing actions (Kajimoto, Osami, Blueberries & Eyesight, Food Style 21, (3), 3, March, 1999).
During World War 2, British fighter pilots regularly consumed bilberry (a variety of blueberry) extract prior to entering combat. French researchers found that bilberry helped improve nighttime visual acuity, adjustment to darkness, and recovery from glare (Monograph. Vaccinium myrtillus (bilberry). Altern Med Rev. 2001 Oct;6(5):500-4).
Researchers believe that the phytochemicals in blueberries may reduce inflammatory processes in tissues by increasing cells membranes ability to allow vital nutrients and chemical signals to pass in and out of the cell (Journal of Food Science, Vol. 65, No. 2, 2000).
There is not enough clinical data to prove its sexual health benefit. However, many claim that blueberry enhances taste and smell of semen. In women it improves scent of vaginal pheromones. However these claims are still debated.
Interestingly the CBS has reported that blueberries are one of the top 10 libido and sex drive enhancing natural food sources.
At a 2004 meeting of the American Chemical Society it was reported that a compound found in blueberries (pterostilbene) could be a “potent weapon in the battle against obesity and heart disease through its cholesterol-reducing potential.” The report added that the compound “may help fight cancer” (Research presented by Agnes M. Rimando, August 19, 2004 at the American Chemical Society national meeting in Boston, MA).
Another study, conducted by Mary Ann Lila, Ph.D., Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana-Champaign, indicate that compounds in Wild Blueberries may be effective inhibitors of both the initiation and promotion stages of cancer (Journal of Agricultural and Food Chemistry, 52:6442, 2004; Journal of Food Science , Vol. 65, No. 2, 2000).
A 2004 in vitro study on rats suggests that blueberries may have applications in the prevention of stroke in humans (Norton C, Kalea AZ, Harris PD, Klimis-Zacas DJ. Wild blueberry-rich diets affect the contractile machinery of the vascular smooth muscle in the Sprague-Dawley rat. J Med Food. 2005;8(1):8-13).
Research conducted in 2002 suggests that blueberries may protect the brain against the damage that is normally associated with ischemic stroke (Nutritional Neuroscience, 2002 Dec.; 5(6): 427-31).
Research is currently underway at the USDA’s Arkansas Children’s Nutrition Center to investigate the role blueberries may play in preventing childhood obesity. The National Institute of Aging (NIA) is also conducting blueberry research to identify the effect that a wild blueberry diet could have on stress resistance. Preliminary results indicate that blueberries may be as effective as pharmaceuticals.
Blueberries are also known to relieve diarrhea and constipation.