Blueberries

The King of Fruits

blueberries_1_1Blueberries are the fruits of a shrub that belong to the heath family whose other members include the cranberry and bilberry as well as the azalea and rhododendron. I’d say that the avocado is the the queen of fruits, and blueberries are the king. Blueberries grow in small groups or clusters and range in size from that of a small pea right up to the size of a marble. They are blue to maroon and even purple-black in color, and feature a white-gray waxy “bloom” that covers the berry’s surface and serves as a protective coating.

The skin surrounds a semi-transparent flesh that encases tiny seeds. Cultivated blueberries are typically mildly sweet, whereas those that grow in the wild have a more tart and tangy flavor.

Blueberry History

Blueberries are native to North America where they grow throughout the woodland areas and mountainous regions in the United States and Canada. This fruit has only been recently introduced in Australia and is now widely cultivated in New Zealand. Blueberries were not really cultivated until the beginning of the 20th century, becoming commercially available in 1916.
There are approximately 30 different species of blueberries with different ones growing throughout various regions throughout the world. Several cultivars are now widely grown in New Zealand.
While blueberries played an important role in North American Indian food culture, they were not consumed in great amounts by colonists until the mid-19th century. It is interesting to note that this seems to be related to the fact that people from other countries did not appreciate the blueberry’s tart flavor, and only when sugar became more widely available as a sweetener at this time, did they become more popular.

Blueberry’s Amazing Health Benefits

Packed in this wonderful blue fruit is an amazing collection of antioxidants and nutrients. It’s fantastic taste aside, the saying ‘good things come out of the blue’ really does apply to blueberries. Recent research has revealed that the blueberry really does have some quite amazing health building properties. It appears the blue pigment, anthocyanin, is the major contributor to its high antioxidant levels.
Blueberries are nature’s antioxidant powerhouse and contain higher antioxidant levels than just about every other fruit and vegetable known. Antioxidants prevent cell damage that occurs from everyday wear and tear. It is believed a diet high in antioxidants helps avoid such health problems as cancers and heart disease.

  • Blueberries are the true phyto-nutrient superstars. Fresh or frozen, blueberries have very levels of antioxidants, which combat the damage done by inflammation.
  • These incredible blue fruits contain significant amounts of anthocyanadins, antioxidant compounds that give blue, purple and red colors to fruits and vegetables. Anthocyanins may have anti-diabetic effects as well.
  • Blueberries improve the heart and circulation. New research suggests that blueberries might even protect the heart muscle from damage, Research has found that blueberries deliver 38% more anthocyanins of than red wine. Blueberries are also a good source of vitamin E, which has numerous positive effects on the heart and circulation.
  • Blueberries contain ellagic acid, another phytochemical that has been shown to prevent cell damage. Ellagic acid blocks metabolic pathways that can lead to cancer. In a study of over 1,200 elderly people, those who ate the most strawberries (another berry that contains ellagic acid) were three times less likely to develop cancer than those who ate few or no strawberries at all.
  • Blueberries are a very good source of vitamin C, manganese, and both soluble and insoluble fibre like pectin.
  • Blueberries contain soluble fibre. Blueberries are high in the soluble fibre called pectin, which has been shown to lower cholesterol and to prevent bile acid from being transformed into a potentially cancer-causing form, leading to bowel cancer.
  • Blueberries promote good eyesight and assist in the prevention of macular degeneration. A study published in the Archives of Ophthalmology indicates that eating 3 or more servings of fruit per day may lower your risk of age-related macular degeneration (ARMD), the primary cause of vision loss in older adults, by 36%, compared to persons who consume less than 1.5 servings of fruit daily.
  • Blueberries improve night time acuity. Extracts of bilberry, a cousin of blueberry, have been shown in numerous studies to improve night 1time visual acuity and promote quicker adjustment to darkness and faster restoration of visual acuity after exposure to glare. This research was conducted to evaluate claims of bilberry’s beneficial effects on night vision made by British Air Force pilots during World War II who regularly consumed bilberry preserves before their night missions.
  • Blueberries may protect against bowel cancer. Laboratory studies show that phenolic compounds in blueberries can inhibit colon cancer cell proliferation and induce apoptosis (programmed cell death). Extracts of the blueberry phenols were separated into phenolic acids, tannins, flavonols, and anthocyanins. Flavonol and tannin fractions cut cell proliferation in half at concentrations of 70-100 and 50-100 microg/mL, while the phenolic fraction was also effective, but less potent, reducing proliferation by half at concentrations of 1000 microg/mL.
  • Blueberries are protective of the urinary function. Blueberries promote urinary tract health, because they contain the same compounds found in cranberries that help prevent or eliminate urinary tract infections. In order for bacteria to infect, they must first adhere to the mucosal lining of the urethra and bladder. Components found in cranberry and blueberry juice reduce the ability of E. coli, the bacteria that is the most common cause of urinary tract infections, to adhere, thus preventing infections.
  • Blueberries may protect against ovarian cancer. Among their rich supply of phytonutrients, blueberries include a flavonoid called kaempferol. The Nurses Health Study (involving 66,940 women) between 1984 and 2002 revealed that women whose diets provided the most kaempferol had a 40% reduction in risk of ovarian cancer, compared to women eating the least kaempferol-rich foods. The foods richest in kaempferol include plain tea, onions, leeks, spinach, and broccoli.
  • Blueberries are often referred to as ‘brain berries‘, several leading scientists suggest eating half a cup of blueberries a day to protect and even promote brain function. In laboratory animal studies, researchers have found that blueberries help protect the brain from oxidative stress and may reduce the effects of age-related conditions such as Alzheimer’s disease or dementia. Researchers found that diets rich in blueberries significantly improved both the learning capacity and motor skills of ageing animals, making them mentally equivalent to much younger ones.

Blueberries have a very high ORAC rating

The ORAC Rating was created by researchers for the USDA at Tufts University in Boston, Massachusetts. You may or may not have probably heard about “ORAC”, but what does it mean? This well-used acronym is short for Oxygen Radical Absorbance Capacity.

Scientists developed this new laboratory test to measure the oxygen radical absorption capacity of different foods and natural substances. It is now one of the most sensitive and reliable methods for measuring antioxidant capacity.

This test measures the time it takes for the antioxidant to inhibit free radicals. It also measures the scale or degree of the free radical inhibition.

This test is one of the most popular tests being used today to rank the antioxidant potential of foods. Recent USDA research and testing has listed blueberries as number one when this test was used to study popular fruits.

Blueberries are highest in antioxidant capacity per serving, compared with more than 20 other fruits. (Source: Journal of Agricultural and Food Chemistry, 52:4026-4037, 2004)

The study showed that a one-cup serving of blueberries had higher antioxidant capacity than a serving of other popular fruits such as cranberries, strawberries, prunes, and raspberries.

This recent research by the USDA is the most comprehensive study and uses the Oxygen Radical Absorbance Capacity test because it is the most advanced way to study the power of antioxidants in various foods and substances.

Blueberries Contain Oxalic Acid

Oxalates (ethanedioate) are chemical compounds that are found naturally in certain plants. If you suffer from kidney stones you may be sensitive or reacting to the oxalates found in oxalate rich plants such as spinach, rhubarb, Swiss chard (silverbeet), berries (all), quinoa, chocolate, cocoa, black tea, soy products, parsley and leeks. If you have kidney stones or are missing a portion of your intestinal tract or simply have trouble with digesting fats (because of gallbladder dysfunction), then you may need to follow a low oxalate diet.

Blueberries are among a small number of foods that contain measurable amounts of oxalic acid,a naturally-occurring substances found in plants, animals, and human beings. Oxalates can cause some concerns with people who have kidney or gallbladder problems, and these acids can even crystallise in some parts of the body. I generally advise patients with already existing ( or untreated) kidney or gallbladder problems to reduce or even avoid oxalate containing foods for some time.

Do Oxalates Interfere With Calcium Absorption?

Not really, laboratory studies have shown that oxalates may potentially interfere with the absorption of calcium from the body. Yet in several peer-reviewed research studies I have seen, the ability of oxalates to lower calcium absorption is exceedingly small and definitely does not outweigh the ability of oxalate-containing foods to contribute significantly enough to calcium loss from your healthy diet. If your digestive system is healthy, you have no yeast infection or dysbiosis  or gut fermentation and you do a good job of chewing and relaxing while you enjoy your meals, then you will get significant benefits, including the absorption of calcium from calcium-rich foods plant foods that also contain oxalic acid. Don’t worry!

Try these quick blueberry ideas…

  • Add blue berries to lunches – both adults and children.
  • Make blueberry smoothie by blending one cup of mild (standard or soy) milk with one cup of blueberries (fresh or frozen). A banana, yogurt or ice cream if you wish. If the blender container is plastic, allow berries a few minutes to soften, so they will not damage the blender.
  • Sprinkle blueberries over your breakfast cereal.
  • Frozen blueberries – defrost first, then place half a cup in your cereal bowl then top with your favourite cereal and a spoonful of yogurt.
  • Toss blueberries through leafy greens or coleslaw for a refreshing lift.
  • Garnish savoury meals with blueberries and sprinkle of herbs.
  • Blueberries, sliced strawberries and raspberries make a delicious fruit platter. Dust with icing sugar if you wish.
  • Frozen blueberries are a healthy, tasty ‘lolly’ option for kids.
  • For a deliciously elegant dessert, layer yogurt and blueberries in wine glasses and top with crystallised ginger.
  • Blueberry pie and  Blueberry Muffins are classic favourites that can be enjoyed throughout the year.

References

  • Andres-Lacueva C, Shukitt-Hale B, Galli RL, Jauregui O, Lamuela-Raventos RM, Joseph JA. Anthocyanins in aged blueberry-fed rats are found centrally and may enhance memory. Nutr Neurosci. 2005 Apr;8(2):111-20. 2005. PMID:16053243.
  • Bickford PC, Gould T, Briederick L, et al. Antioxidant-rich diets improve cerebellar physiology and motor learning in aged rats. Brain Res 2000 Jun 2;866(1-2):211-7 2000.
  • Bomser, J., et al.  In vitro anticancer activity of fruit extracts from Vaccinium species.  Planta Medica.  62(3):212-216, 1996.
  • Cho E, Seddon JM, Rosner B, Willett WC, Hankinson SE. Prospective study of intake of fruits, vegetables, vitamins, and carotenoids and risk of age-related maculopathy. Arch Ophthalmol. 2004 Jun;122(6):883-92. 2004. PMID:15197064.
  • Craig W. Phytochemicals: guardians of our health. J Am Diet Assoc. 1997;97(Suppl 2) S199-S204 1997.
  • Ensminger AH, Esminger M. K. J. e. al. Food for Health: A Nutrition Encyclopedia. Clovis, California: Pegus Press; 1986 1986. PMID:15210.
  • Gates MA, Tworoger SS, Hecht JL, De Vivo I, Rosner B, Hankinson SE. A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer. Int J Cancer. 2007 Apr 30; [Epub ahead of print] 2007. PMID:17471564.
  • Hope Smith, S., et al.  Antimutagenic activity of berry extracts.  J Med Food.  7(4):450-455, 2004.
  • Joseph JA, Denisova NA, Bielinski D, et al. Oxidative stress protection and vulnerability in aging: putative nutritional implications for intervention. Mech Ageing Dev 2000 Jul 31;116(2-3):141-53 2000.
  • 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 1999. PMID:13000.
  • Kalt, W., et al.  Effect of blueberry feeding on plasma lipids in pigs.  British Journal of Nutrition.  2007.
  • Kota BP, Huang TH, Roufogalis BD. An overview on biological mechanisms of PPARs. Pharmacol Res. 2005 Feb;51(2):85-94. 2005. PMID:15629253.
  • Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. Polyphenols: food sources and bioavailability. Am J Clin Nutr. 2004 May;79(5):727-47. 2004. PMID:15113710.
  • Prior RL, Lazarus SA, Cao G, et al. Identification of procyanidins and anthocyanins in blueberries and cranberries (vaccinium spp.) using high-performance liquid chromatography/mass spectrometry. J Agric Food Chem 2001 Mar;49(3):1270-6 2001.
  • Rimando A. Pterostilbene as a new natural product agonist for the peroxisome proliferators-activated receptor alpha isoform. Paper presented at the 228th American Chemical Society National Meeting, Philadelphia, PA, August 23, 2004. 2004.
  • 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. 2004. PMID:15264904.
  • Sanchez-Moreno C, Cao G, Ou B, Prior RL. Anthocyanin and proanthocyanidin content in selected white and red wines. Oxygen radical absorbance capacity comparison with nontraditional wines obtained from highbush blueberry. J Agric Food Chem. Aug 13;51(17):4889-96 2003.
  • Shukitt-Hale B, Carey AN, Jenkins D, Rabin BM, Joseph JA. Beneficial effects of fruit extracts on neuronal function and behavior in a rodent model of accelerated aging. Neurobiol Aging. 2006 Jul 10; [Epub ahead of print] 2006. PMID:16837106.
  • Tufts University. Researching a Blueberry/Brain Power Connection. Tufts University Health and Nutrition Letter, March 2001, Vol. 19. Number 1 2001.
  • Tyler VE. Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York: Pharmaceutical Products Press 1994, 51-4 1994.
  • Wang Y, Chang CF, Chou J, Chen HL, Deng X, Harvey BK, Cadet JL, Bickford PC. Dietary supplementation with blueberries, spinach, or spirulina reduces ischemic brain damage. Exp Neurol. 2005 May;193(1):75-84. 2005. PMID:15817266.
  • Wood, Rebecca. The Whole Foods Encyclopedia. New York, NY: Prentice-Hall Press; 1988 1988. PMID:15220.
  • Wu X, Beecher GR, Holden JM, Haytowitz DB, Gebhardt SE, Prior RL. Concentrations of Anthocyanins in Common Foods in the United States and Estimation of Normal Consumption. J Agric Food Chem. 2006 May 31;54(11):4069-4075. 2006. PMID:16719536.
  • 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. 2005. PMID:16131149.
  • Youdim KA, Shukitt-Hale B, MacKinnon S, et al. Polyphenolics enhance red blood cell resistance to oxidative stress: in vitro and in vivo. Biochim Biophys Acta 2000 Sep 1;1523(1):117-22 2000.

Comments on this entry are closed.

Previous Post:

Next Post: