The Mighty Blueberry

Photo by  Kim Gorga  on  Unsplash

Photo by Kim Gorga on Unsplash

Because the holiday season is so heavily associated with carbohydrate full, nutrition poor, and sugar laden foods, I wanted to share a piece on one of my favorite, nutritious foods: the blueberry. Enjoy the holiday foods—but hopefully this serves as a reminder to incorporate healing foods too!


The Vaccinium genus embraces 43 different types of berries: blueberries, bilberries, huckleberries, farkleberries, cranberries, lingonberries, and more. There are several varieties of blueberries alone. The United States Department of Agriculture (USDA) addresses the Vaccinium genus with the common name blueberry. Similarly, the Vaccinium genus is represented by the blueberry in the scientific literature, unless otherwise specified. (1, 2)

            Blueberries are native to North America and Europe and are grown in several regions of the United States. The blueberry was not domesticated for commercial cultivation until the early 1900s by Elizabeth White, the daughter of a cranberry grower, and USDA botanist Frederick Coville. However, Native American populations acknowledged the blueberry well before commercial growers did and utilized the blueberry for culinary and traditional medicine applications. (1,3)

            The interest and appreciation for blueberries surged in the later part of the 20thcentury. In 1974, the USDA declared July as National Blueberry Month. In the 1990s, research in the therapeutic benefits of blueberries began in earnest. (3) Maine, Michigan, and New Jersey are the top blueberry producers in the U.S. (4) Blueberries are produced worldwide; and between 5 continents, in 2014, over 1 billion pounds were produced! (3)

Antioxidant and Nutrient Powerhouse

Blueberries are a significant source of blue-purple pigments called anthocyanins. These pigments are powerful antioxidants. (5) It is important to include sources of antioxidants in the diet. They scavenge free radicals, which are molecules that have an unpaired electron. Molecules like to have electrons in pairs, and molecules with an unpaired electron will “steal” an electron from another molecule. But then the second molecule has an unpaired electron and will need to steal an electron for itself! Free radicals create a cascade of chaos, leading to oxidative stress (too many free radicals at work), which is implicated in a variety of chronic diseases. (6)

            In addition to anthocyanins, blueberries contain high levels of ascorbic acid (vitamin C).(6) Blueberries are excellent sources of folic acid and fiber. (7) They do provide a small amount of a variety of other minerals and vitamins such as phosphorus, potassium, calcium, and vitamin K. (8)

Health Benefits

Blood Sugar Management

            It is thought that the anthocyanins in blueberries decrease insulin resistance. Insulin is the hormone that is supposed to keep blood glucose in check by lowering it. However, sometimes the body becomes resistant to insulin activity and blood glucose remains high. A study utilizing smoothies from freeze-dried blueberries for six weeks (equivalent to 2 cups of fresh blueberries daily) demonstrated that regular dietary consumption of blueberries decreased insulin resistance. (9)

Anthocyanins in general have anti-diabetic effects. Similar to the prescription drug acarbose, anthocyanins can inhibit the enzymes that break down carbohydrates during digestion, thereby limiting the amount of glucose released from food into the bloodstream. Anthocyanins may aid in the ability of muscles to uptake glucose and prohibit fat cells from promoting insulin resistance. (10)

Cardiovascular Health

         The development of plaque and subsequent narrowing in the arteries (atherosclerosis) is the most common cause of cardiovascular disease. Atherosclerosis can result in fatal consequences, namely heart attacks and strokes. The development of cardiovascular disease is aggravated by oxidative stress caused by reactive oxygen species. (11)

            Researchers are hopeful that dietary anthocyanins may provide cardiovascular protection in and of themselves or elucidate new supplemental or pharmaceutical antioxidant applications. Anthocyanins may reduce the inflammatory process that contributes to atherosclerosis, decrease endothelial (vasculature) dysfunction, and decreased nitric oxygen (NO) release. NO, while it does dilate blood vessels, is sometimes implicated in blood vessel damage, which can promote the development of atherosclerosis. (11)

            A small study evaluated the effects of a single serving of blueberries (300 g) on vascular tone and oxidative activity. While one serving did not elicit vascular changes, it did demonstrate marked reduction in ROS damage to DNA. (12) Another study, utilizing a blueberry beverage equivalent to 2 cups of fresh berries, found that after 8 weeks, daily consumption resulted in decreased blood pressure. In addition to lower blood pressure, participants consuming the blueberry beverage had lowered oxidized low-density lipoprotein (ox-LDL) levels. Both elevated blood pressure and ox-LDL are associated with increased risk for cardiovascular disease. (13)

Cognitive Function

            In general, consumption of fruit and vegetables is associated with decreased risk of neurodegenerative diseases, like dementia, and better cognitive function in the aging population. Blueberries specifically may be able improve memory and motor function. This is attributed to the activity of the anthocyanins. These antioxidants can even be found in the regions of the brain responsible for memory and fine motor skills, meaning they can cross the blood brain barrier! (14)

         Consuming blueberry juice every day for 12 weeks resulted in improved cognitive function in older adults with early signs of neurodegenerative disease. While statistically insignificant, data from this small study suggested the blueberry juice had an anti-depressant effect, lowered blood lipid levels, and lowered blood glucose too. (14)

Eye Health

         Research indicates blueberries protect eye health. Free radicals can damage the eyes, resulting in cataract formation and macular degeneration. The in vitro antioxidant activity of blueberries is comparable to the activity of pharmaceuticals for these conditions. In addition to decreasing free radical activity in the eye, blueberries increase the blood and oxygen supply to the eyes. All of this research is preliminary; so, hopefully, more research will be done to further investigate the use of blueberries for human eye health. (14)

Serving Suggestions

            One cup of fresh blueberries is a serving. Each serving contains about 80 calories, 3.6 g of fiber, 21 g of carbohydrates, and 1 g of protein. One cup of blueberries provides 114 g of potassium. (8) However, research studies use what approximates to 2 cups of fresh blueberries a day to achieve a therapeutic dose. (9,12,13,14)

Selection, Preparation, and Storage

         When ripe, blueberries are a dark blue-purple. Blueberries that are slightly red are not ripe, and blueberries will not continue to ripe after picking. Blueberries that are moldy or shriveled up are not good for eating. Juice stains on a berry container are a good indication the berries are bruised. Blueberries should be refrigerated and consumed within 10 days of purchase. Wash blueberries before eating them. (15)

            If purchasing frozen blueberries, make sure the blueberries are not frozen in a large clump. This indicates the bag has thawed and refrozen at least once. Nutritionally, frozen blueberries are equivalent to fresh blueberries. Anthocyanin content does not change. However, dried blueberries have significantly fewer anthocyanins, but their antioxidant activity is similar to frozen or fresh blueberries. It is thought that the chemical byproducts of breaking down anthocyanins are antioxidants too.(5) Thawed blueberries should be used within 3 days. (15)

            Blueberries are ranked number 16 on the Environmental Workings Group’s list of produce most heavily treated with pesticides. (16) Buy organic or spray free whenever possible. There are no genetically modified blueberries. (17)

Purple Power Smoothie

Serves 1

Prep time: 5 minutes

  • 1-2 cups of frozen blueberries

  • A handful of leafy greens (spinach recommended)

  • 1/3 cu. almond milk

  • 1 tbs. almond butter

  • 1 tbs. ground flax seed

Optional: chocolate or vanilla protein powder, collagen powder, and/or psyllium husk powder. The addition of psyllium husk powder increases fiber content of the smoothie and gives it a fun, thick, mousse-like texture. 

1.    Place all ingredients in a blender. Blend until smooth. Add or subtract liquids to desired consistency. Ice cubes or more frozen fruit can be added for a thicker smoothie.

2.    Pour into cups and enjoy!

Blueberry Bliss Salad (18)

Serves 1

Prep time: 5 minutes

  • ½ cu. fresh blueberries

  • Generous handful of leafy greens

  • ½ cu. of chopped nuts (walnut or hazelnut will do)

  • ½ cu. diced cucumber

  • ½ cu. chevre

  • 1 tbs. extra virgin olive oil

  • 1 tsp. honey (optional)

  • ½ tbs. lemon juice

  • ½ tsp. oregano

  • Salt and pepper to taste

 1.    For the dressing, mix in a small dish the lemon juice, oregano, honey, then the olive oil. 

2.    Combine all other ingredients in serving bowl.

3.    Add the dressing.

4.    Sprinkle with salt and pepper to taste.

Reminder: I am a student. This post is for educational and informational purposes only.  I am not a physician or a nutritionist. If you need help modifying your diet and/or have health concerns, please get in touch with a credentialed professional.  

References

  1. Lyrene P, Vorsa N, and Ballington J. Polyploidy and sexual polyploidization in the genus VacciniumEuphytica. 2003;133:27-36. doi: 10.1023/A:1025608408727.

  2. United States Department of Agriculture: Natural Resources Conservation Service. VacciniumL. blueberry. Available at: https://plants.usda.gov/core/profile?symbol=VACCI#. Accessed June 8, 2018.

  3. U.S. Highbush Blueberry Council. History of Blueberries. Available at: https://www.blueberrycouncil.org/about-blueberries/history-of-blueberries/. Accessed June 8, 2018.

  4. United States Department of Agriculture: Economics, Statistics, and Market Information System. U.S. Blueberry Industry. Available at: http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1765. Accessed June 8, 2018. 

  5. Lohachoompol V, Srzednicki G, and Craske J. The change of total anthocyanins in blueberries and their antioxidant effect after drying and freezing. J Biomed Biotechnol. 2004;5:248-252. 

  6. Skrovankova S, Sumczynski, Mleck J, Juirkova T, Sochor J. Bioactive compounds and antioxidant activity in different types of berries. Int J Mol Sci.2015;16:24673-24706. doi: 10.3390/ijms161024673.

  7. Jung H, Lim Y, and Kim E. Therapeutic phytogenic compounds for obesity and diabetes. Int J Mol Sci. 2014;15:21505-21537. doi: 10.3390/ijms151121505.

  8. United State Department of Agriculture: National Nutrient Database for Standard Reference Legacy Release. Basic Report: 09050, Blueberries, raw. Available at: https://ndb.nal.usda.gov/ndb/foods/show/09050?fgcd=&manu=&format=&count=&max=25&offset=&sort=default&order=asc&qlookup=blueberries&ds=&qt=&qp=&qa=&qn=&q=&ing=. Updated April 2018. Accessed June 9, 2018.

  9. Stull A, Cash K, Johnson W, Champagne C, and Cefalu W. Bioactives in blueberries improve insulin sensitivity in obese, insulin-resistant men and women. J Nutr. 2010;140(10):1764-1768. doi: 10.3945/jn.110.125336

  10. Belwal T, Nabavi S, Nabavi S, and Habtemarian S. Dietary anthocyanins and insulin resistance: When food becomes a medicine. Nutrients. 2017;9(10):1111. doi: 10.3390/nu9101111. 

  11. Reis J, Monteiro V, Souza Gomes R, et al. Action mechanism and cardiovascular effect of anthocyanins: a systematic review of animal and human studies. J Transl Med. 2016;14:315. doi: 10.1186/s12967-016-1076-5.

  12. Del B, Riso P, Campolo J, et al. A single portion of blueberry (Vaccinium corymbosumL) improves protection against DNA damage but not vascular function in healthy male volunteers. Nutr Res. 2013;33(3):220-227. doi: 10.1016/j.nutres.2012.12.009.

  13. Basu A, Du M, Leyva M, et al. Blueberries decrease cardiovascular risk factors in obese men and women with metabolic syndrome. J Nutr. 2010;140(9):1582-1587. doi: 10.3945/jn.110.124701.

  14. Krikorian R, Shidler M, Nash T, et al. Blueberry supplementation improves memory in older adults. J Agric Food Chem. 2010;58(7):3996-4000. doi: 10.1021/jf9029332.

  15. U.S. Highbush Blueberry Council. Buying Blueberries. Available at: https://www.blueberrycouncil.org/blueberry-cooking-tips/buying-blueberries/. Accessed June 9, 2018.

  16. Environmental Working Group. EWG’s 2018 Shopper’s Guide to Pesticides in Produce. Available at: https://www.ewg.org/foodnews/full-list.php. Accessed June 9, 2018.

  17. International Service for the Acquisition of Agri-Biotech Applications. GM Approval Database. Available at: http://www.isaaa.org/gmapprovaldatabase/advsearch/default.asp?CropID=Any&TraitTypeID=Any&DeveloperID=Any&CountryID=US&ApprovalTypeID=Any. Accessed June 9, 2018.

  18. Adapted from broccoliandmuffins.com. Original recipe available at: http://broccoliandmuffins.com/blueberry-arugula-salad/. Accessed June 9, 2018.