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Blueberries

One of Nature’s Most Potent Antioxidants Offers Powerful Neuroprotective and Other Benefits By Russell Martin

Benefits for Other Body Systems

Blueberries’ benefits for neurological health and vigor are so well established as to make daily consumption of the fruit a “no-brainer” for virtually everyone. Moreover, new studies continue to confirm blueberries’ remarkable health-promoting effects in other areas of the human body.

For decades, researchers in Europe have documented evidence of the ability of bilberries to combat a range of eye disorders. During World War II, French researchers who examined bilberry extract’s effects in pilots found that bilberry helped improve nighttime visual acuity, adjustment to darkness, and recovery from glare.6 In another study, all eight patients with glaucoma who were given a single oral dose of bilberry extract demonstrated improvements based on electroretinography, a measure of electrical responsiveness of the retinal cells. Bilberry’s antioxidant properties may protect against glaucoma by supporting healthy intraocular pressure.6 In a clinical study, the combination of bilberry extract with vitamin E stopped the formation of senile cortical cataracts in 48 of 50 patients.6 Researchers believe that the anthocyanins and proanthocyanidins found in blueberries might similarly offer benefits for eye health.

In an article in the Journal of Agricultural and Food Chemistry in 2004, researchers announced that they had isolated three compounds in blueberries and other dark-pigmented berries known to lower cholesterol levels.22 In a follow-up study, one of the three phytochemicals—pterostilbene—showed a particularly potent effect in stimulating a receptor protein in cells that plays an important role in lowering cholesterol and other blood fats.3 “We are excited to learn that blueberries, which are already known to be rich in healthy compounds, may also be a potent weapon in the battle against obesity and heart disease,” lead author Agnes Rimando told members of the American Chemical Society.3,22,23

Blueberry juice or extract may help avert urinary tract infections commonly suffered by women. Scientists formerly hypothesized that dark-pigmented berries such as cranberry help fight infection through an antibacterial effect caused by the acidification of urine.4 Current research suggests that berries, including cranberry and blueberry, may fight bacterial urinary infections by preventing E. coli and other forms of bacteria from adhering to cells lining the walls of the urinary tract.4,5

Blueberries also may slow the growth of cancer cells. In 2001, University of Mississippi researchers conducting in-vitro tests found that blueberry and strawberry extracts were remarkably successful in slowing the growth of two aggressive cervical cancer cell lines and two fast-replicating breast cancer cell lines, with the blueberry extract performing best against the cervical cancer cells.8 Last year, a University of Georgia study similarly 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.9 Further studies are indicated to determine whether phytochemicals from dark-pigmented berries may affect very early growth of malignant cells in the bodies of humans as well.

NEW FINDINGS ON BLUEBERRIES

New research reported in peer-reviewed journals by scientists around the world confirms the wide range of health benefits attributed to blueberries, while pointing to promising new therapeutic applications:

• In a study published in the journal Nutritional Neuroscience,24 a blueberry-supplemented diet was found to greatly enhance the spatial memory of laboratory animals. When later studied in vitro, the animals’ brains demonstrated structural changes associated with an improved capacity for learning. Researchers believe the two findings are directly correlated.

• In a study reported in the Journal of Agricultural and Food Chemistry, cold-pressed blueberry, Marionberry, boysenberry, and red raspberry seed oils were evaluated for their fatty acid composition. The oils were found to contain antioxidants with a high capacity to absorb oxygen radicals, and were deemed potent sources of tocopherols, carotenoids, and natural antioxidants.25

• The Journal of Medicinal Food reported that in an in-vitro study of aortic tissue of young rats, wild blueberries incorporated in the diet positively affect the plasticity of vascular smooth muscle, but have no deleterious effect on membrane sensitivity. This finding suggests that blueberries may have applications in helping prevent heart disease and stroke in humans.26

• In a similar study published in the Journal of Nutritional Biochemistry, researchers demonstrated that in rat aortic tissue, compounds from berry extracts caused cell changes that may affect cellular signal transduction pathways and contribute to improved cardiovascular health.27

• Research published in the journal Neurobiology of Aging showed that nutritional antioxidants found in blueberries can reverse age-related declines in neuronal signal transduction as well as cognitive and motor deficits. The investigators speculated that blueberry supplementation may also help slow declines in brain function that accompany diseases such as amyotrophic lateral sclerosis, Alzheimer’s disease, and Parkinson’s disease.28

• In an in-vitro study published in Biochemistry and Cell Biology, 24 hours of exposure to extracts of blueberry antioxidants sharply reduced the production of matrix metalloproteinases—enzymes believed to play key roles in malignant tissue metastasis—in human prostate cancer cells. This led the researchers to postulate that blueberry supplementation may help prevent tumor metastasis.29

Conclusion

Although no studies to date have compared the relative efficacy of fresh blueberries versus frozen berries, canned berries, or berry extracts, each form of the fruit has been shown to contain the essential anthocyanins and proanthocyanidins that make blueberries one of the most exciting nutraceuticals being researched and consumed today. Blueberry extracts have the advantage of delivering the fruit’s phytochemicals in a simple, standardized dose, while consuming blueberries as food offers the benefit of flavor.

Regardless of how they are consumed, blueberries should be considered a mainstay of every healthy diet. This remarkable fruit, known for centuries for its medicinal properties, continues to prove itself in research laboratories around the world, demonstrating a wide array of dramatic, health-enhancing benefits.

References

1. Underwood A. So berry good for you; rediscovering the health benefits of berries. Newsweek. June 17, 2002.

2. Wu X, Beecher GR, Holden JM et al. Lipophilic and hydrophilic antioxidant capacities of common foods in the United States. J Agric Food Chem. 2004 Jun 16;52(12):4026-37.

3. Rimando AM, Nagmani R, Feller DR, Yokoyama W. Pterostilbene, a new agonist for the peroxisome proliferator-activated receptor alpha-isoform, lowers plasma lipoproteins and cholesterol in hypercholesterolemic hamsters. J Agric Food Chem. 2005 May 4;53(9):3403-7.

4. Zafriri D, Ofek I, Adar R, Pocino M, Sharon N. Inhibitory activity of cranberry juice on adherence of type 1 and type P fimbriated Escherichia coli to eucaryotic cells. Antimicrob Agents Chemother. 1989 Jan;33(1):92-8.

5. Ofek I, Goldhar J, Zafriri D, et al. Anti-Escherichia coli adhesin activity of cranberry and blueberry juices. N Engl J Med. 1991 May 30;324(22):1599.

6. No authors. Monograph. Vaccinium myrtillus (bilberry). Altern Med Rev. 2001 Oct;6(5):500-4.

7. Faria A, Oliveira J, Neves P, et al. Antioxidant properties of prepared blueberry (Vaccinium myrtillus) extracts. J Agric Food Chem. 2005 Aug 24;53(17):6896-902.

8. 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.

9. 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.

10. Available at: www.blueberry.org/blueberries.htm. Accessed November 16, 2005.

11. Bagchi D, Garg A, Krohn RL, et al. Protective effects of grape seed proanthocyanidins and selected antioxidants against TPA-induced hepatic and brain lipid peroxidation and DNA fragmentation, and peritoneal macrophage activation in mice. Gen Pharmacol. 1998 May;30(5):771-6.

12. Cao G, Shukitt-Hale B, Bickford PC, et al. Hyperoxia-induced changes in antioxidant capacity and the effect of dietary antioxidants. J Appl Physiol. 1999 Jun;86(6):1817-22.

13. Kay CD, Holub BJ. The effect of wild blueberry (Vaccinium angustifolium) consumption on postprandial serum antioxidant status in human subjects. Br J Nutr. 2002 Oct;88(4):389-98.

14. 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.

15. Brasher P. Blueberries may aid balance, memory. Associated Press. September 17, 1999.

16. Galli RL, Bielinski DF, Szprengiel A, Shukitt-Hale B, Joseph JA. Blueberry supplemented diet reverses age-related decline in hippocampal HSP70 neuroprotection. Neurobiol Aging. 2005 Apr 30.

17. Proctor CJ, Soti C, Boys RJ, et al. Modelling the actions of chaperones and their role in aging. Mech Ageing Dev. 2005 Jan;126(1):119-31.

18. Andres-Lacueva C, Shukitt-Hale B, Galli RL, et al. Anthocyanins in aged blueberry-fed rats are found centrally and may enhance memory. Nutr Neurosci. 2005 Apr;8(2):111-20.

19. Wang Y, Chang CF, Chou J, et al. Dietary supplementation with blueberries, spinach, or spirulina reduces ischemic brain damage. Exp Neurol. 2005 May;193(1):75-84.

20. de RC, Shukitt-Hale B, Joseph JA, Mendelson JR. The effects of antioxidants in the senescent auditory cortex. Neurobiol Aging. 2005 Jun 9.

21. Willis L, Bickford P, Zaman V, Moore A, Granholm AC. Blueberry extract enhances survival of intraocular hippocampal transplants. Cell Transplant. 2005;14(4):213-23.

22. Rimando AM, Kalt W, Magee JB, Dewey J, Ballington JR. Resveratrol, pterostilbene, and piceatannol in vaccinium berries. J Agric Food Chem. 2004 Jul 28;52(15):4713-9.

23. Available at: http://www.rcentre.utm.my/ news.php?cat=-1&archived=1. Accessed November 25, 2005.

24. 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.

25. Parry J, Su L, Luther M, Zhou K, et al. Fatty acid composition and antioxidant properties of cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils. J Agric Food Chem. 2005 Feb 9;53(3):566-73.

26. 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.

27. Kalea AZ, Lamari FN, Theocharis AD, et al. Wild blueberry (Vaccinium angustifolium) consumption affects the composition and structure of glycosaminoglycans in Sprague-Dawley rat aorta. J Nutr Biochem. 2005 Aug 17.

28. Lau FC, Shukitt-Hale B, Joseph JA. The beneficial effects of fruit polyphenols on brain aging. Neurobiol Aging. 2005 Sep 26.

29. Matchett MD, Mackinnon SL, Sweeney MI, Gottschall-Pass KT, Hurta RA. Blueberry flavonoids inhibit matrix metalloproteinase activity in DU145 human prostate cancer cells. Biochem Cell Biol. 2005 Oct;83(5):637-43.