WHAT WE KNOW
Blueberries have always been delicious, especially when those tiny blue-black gems are foraged for in the wild.
But in recent years, the fruit of yogurt-toppings and pie-filling has become famous as a superfood. The reason, as with so many superfoods, is their high amount of antioxidants, which are excellent at inhibiting free radicals that damage cells.
Additional research suggests that blueberries may have anti-inflammatory properties and may also help prevent some degenerative diseases and malignancies. Studies are currently being conducted on how blueberries may be beneficial in relation to blood pressure, eye health, neurodegeneration, improved memory, delay of cognitive aging, lowering the risk of cancer, and in the reduction of Parkinson’s Disease.
Cautions and warnings
If you are taking blood thinners, consult a health care practitioner prior to consuming.
In this study, researchers used samples from countries worldwide and assayed the samples for their total antioxidant content using a modified version of the FRAP assay. The researchers found that berries have high antioxidant values.
Carlsen MH, Halvorsen BL, Holte K, Bøhn SK, Dragland S, Sampson L, Willey C, Senoo H, Umezono Y, Sanada C, Barikmo I, Berhe N, Willett WC, Phillips KM, Jacobs DR Jr, Blomhoff R. The total antioxidant content of more than 3100 foods, beverages, spices, herbs and supplements used worldwide. Nutr J. 2010 Jan 22;9:3.
In this study, a variety of wild berries (including blueberries) were tested to discover the oxygen radical absorption capacity (ORAC) in the raw berries. The research concluded that “Alaska wild berries (including blueberries) have extraordinarily high antioxidant levels.”
Ten females consumed a blueberry smoothie or placebo of a similar antioxidant capacity five and 10 hours prior to and then immediately 12 and 36 hours after exercise-induced muscle damage (EIMD). This study demonstrates that “the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength.”
McLeay, Y., Barnes, M. J., Mundel, T., Hurst, S. M., Hurst, R. D., & Stannard, S. R. (2012). Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage. Journal of the International Society of Sports Nutrition, 9, 19.
Blueberries are a source of eight phenolic acids, which have antioxidant and anti-inflammatory effects. This report shows that chlorogenic acid was found to be the more predominant one.
Blueberries have been found to reduce inflammatory compounds in human subjects. This study shows that the inflammatory cytokines IL-1β and IL-6 were reduced in patients consuming a concentrated blueberry supplement.
Ono-Moore KD, et al. Postprandial Inflammatory Responses and Free Fatty Acids in Plasma of Adults Who Consumed a Moderately High-Fat Breakfast with and without Blueberry Powder in a Randomized Placebo-Controlled Trial. J. Nutr. 146.7 (n.d.): 1411–419.
This study found that blueberries may reduce an inflammatory response in the colon. The anti-inflammatory effect is likely due to its antioxidant effect, the down-regulation of the expression of inflammatory mediators and inhibition of the nuclear translocation of NF-κB.
Pervin Mehnaz, et al. Preventive and therapeutic effects of blueberry (Vaccinium corymbosum) extract against DSS-induced ulcerative colitis by regulation of antioxidant and inflammatory mediators. Journal of Nutritional Biochemistry, Volume 28, 103–113
Blueberries have been found to be a good source of anthocyanidins which protect cells from oxidative damage.
Huang, W., Zhu, Y., Li, C., Sui, Z., & Min, W. (2016). Effect of Blueberry Anthocyanins Malvidin and Glycosides on the Antioxidant Properties in Endothelial Cells. Oxidative Medicine and Cellular Longevity, 2016, 1591803.
There is ongoing research on the effects of blueberry as it relates to the following health concerns:
May help prevent some degenerative diseases and malignancies (ovarian, melanoma and cervical cell lines have been studied).
Diaconeasa, Z., Leopold, L., Rugină, D., Ayvaz, H., & Socaciu, C. (2015). Antiproliferative and Antioxidant Properties of Anthocyanin Rich Extracts from Blueberry and Blackcurrant Juice. International Journal of Molecular Sciences,16(2), 2352–2365.
This double-blind, placebo-controlled human trial demonstrates that daily blueberry consumption may reduce blood pressure and arterial stiffness, possibly due to increased nitric oxide production.
Johnson Sarah A., et al. Daily Blueberry Consumption Improves Blood Pressure and Arterial Stiffness in Postmenopausal Women with Pre- and Stage 1-Hypertension: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial. Journal of the Academy of Nutrition and Dietetics, Volume 115, Issue 3, 369–377
Blueberry ingestion for six weeks increases NK cells (natural killer cells) and reduces augmentation index, aortic systolic blood pressure, and diastolic pressures in sedentary males and postmenopausal females, suggests this human study.
McAnulty Lisa S., et al. Six weeks daily ingestion of whole blueberry powder increases natural killer cell counts and reduces arterial stiffness in sedentary males and females. Nutrition Research, Volume 34, Issue 7, 577–584
This study examines how gallic acid, found in blueberries, is neuroprotective, prevents neurodegeneration and is an antioxidant.
Daglia Maria, et al. Polyphenols: Well Beyond The Antioxidant Capacity: Gallic Acid and Related Compounds as Neuroprotective Agents: You are What You Eat! Current Pharmaceutical Biotechnology, Volume 15, Number 4, April 2014, pp. 362-372(11)
Blueberries may reduce the spread and growth of triple negative breast cancer cells, and may reduce inflammatory cytokines, according to this study’s findings.
Noriko Kanaya, Lynn Adams, Ayano Takasaki, and Shiuan Chen. Whole Blueberry Powder Inhibits Metastasis of Triple Negative Breast Cancer in a Xenograft Mouse Model Through Modulation of Inflammatory Cytokines. Nutrition And Cancer Vol. 66, Iss. 2, 2014
Evidence is accumulating that consumption of blueberries may be one strategy to prevent or even reverse age-related neuronal deficits.
Improved Eye Health
Pterostilbene, a naturally occurring compound in blueberries, has been studied in relation to how it helps to reduce oxidative damage in the cornea.
Li, J., Ruzhi Deng, Hua, X., Zhang, L., Lu, F., Coursey, T. G., … Li, D.-Q. (2016). Blueberry Component Pterostilbene Protects Corneal Epithelial Cells from Inflammation via Anti-oxidative Pathway. Scientific Reports, 6, 19408.
Anthocyanadins may help to decrease intraocular pressure in glaucoma and ocular hypertension, suggests this study.
To evaluate the protective effect of blueberry anthocyanins on retinal pigment epithelium (RPE) cells, in vitro cell models of replicative senescent and light-induced damage were established in the present study. These results demonstrate that “blueberry anthocyanins extracts are efficacious against senescence and light-induced damage of RPE cells.”
Y. Liu, X. Song, Di Zhang, F. Zhou, D. Wang, Y. Wei, F. Gao, L. Xie, G. Jia, W. Wu, B. Ji. Blueberry anthocyanins: Protection against ageing and light-induced damage in retinal pigment epithelial cells. Br. J. Nutr. 2012 108(1): 16–27.
In this study, researchers investigated the effects of daily consumption of wild blueberry juice in a sample of older adults with early memory changes. The findings of this preliminary study suggest that “moderate-term blueberry supplementation can confer neurocognitive benefit.”
R. Krikorian, M. D. Shidler, T. A. Nash, W. Kalt, M. R. Vinqvist-Tymchuk, B. Shukitt-Hale, and J. A. Joseph. Blueberry supplementation improves memory in older adults. J. Agric. Food. Chem., 58(7): 3996–4000, 2010.
Delayed Cognitive Aging
In this study, researchers fed regulated doses of blueberry supplements to rats. The experiment found that “phytochemicals present in antioxidant-rich foods such as blueberries may be beneficial in reversing the course of neuronal and behavioral aging.”
J. A. Joseph, B. Shukitt-Hale, N. A. Denisova, D. Bielinski, A. Martin, J. J. McEwen, P. C. Bickford. Reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation. J. Neurosci. 1999 19(18): 8114–8121.
Lowered Risk of Cancer
This paper focuses on studies of “whole berries” such as berry extracts and purified fractions, juices, and freeze-dried powders. Potential mechanisms of anticancer action and bioavailability of berry phenolics, as well as gaps in knowledge and recommendations for future berry research, are also briefly discussed.
In this study, researchers investigated whether blueberry extracts rich in anthocyanins, proanthocyanidins, or other polyphenols, suppress the neurotoxic effects of rotenone in a primary cell culture model of Parkinson’s Disease (PD). Their findings suggest that “anthocyanin- and proanthocyanidin-rich botanical extracts such as blueberries, may alleviate neurodegeneration in PD via enhancement of mitochondrial function.”
In this patient trial, researchers examined whether higher intakes of total flavonoids and their subclasses were associated with a lower risk of developing Parkinson’s disease. Their findings suggest that “intake of some flavonoids may reduce Parkinson’s Disease risk, particularly in men.”
AVAILABLE RESEARCH ON CONTRAINDICATIONS
If you are taking blood thinners, consult a health care practitioner prior to use.
This review of literature assesses the use and misuse of various dietary intakes, including blueberries.
Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc: A Report of the Panel on Micronutrients ... and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Washington, D.C.: National Academy, 2001.