The researchers, from the University of Milano, gave 300 grams of ground blueberries to ten adult volunteers (human) or a control jelly in a crossover study design.
The researchers drew blood from the subjects before and after (one and two hours after and 24 hours after) their ingestion of the blueberries. They also conducted the same protocol using the control jam and compared the results.
The researchers found that in just one hour after consuming the ground blueberries, their cellular DNA damage – related to hydrogen peroxide – was reduced by 18% when compared to the control jelly.
The data – confirming other studies – showed that the protection to the cells were related to their antioxidant potential. The researchers stated in their conclusion that, “one portion of blueberries seems sufficient to improve cell antioxidant defense against DNA damage.”
This ability of blueberries to protect cells from damage from free radicals has been seen in other studies, including those showing blueberries benefit memory and may help stave off Alzheimer’s disease.
Other research has determined that blueberries can improve immunity and reduce metabolic syndrome-related issues.
Illustrating this, a study from Louisiana State University gave blueberry extract or a placebo twice daily to 32 obese patients with insulin resistance. After six weeks the researchers found that the blueberry group had significantly less insulin resistance.
In another study from Appalachian State University, 12 human subjects were given 250 grams of blueberries a day while 13 others acted as controls. After six weeks the researchers found that the blueberry group had significantly higher natural killer cell counts – a sign of increased immunity.
In a study from Oklahoma State University of 48 people with metabolic syndrome were given either 400 grams of blueberries a day or not. The blueberry group had significantly lower LDL-cholesterol levels and reduced symptoms of metabolic disease otherwise.
Blueberries contain judicious quantities of a special category of phyronutrients called anthocyanins. These include cyanidins, delphinidins, malvidins, pelargonidins and peonidins. Anthocyanins are significantly antioxidant and they help protect the cells from the damaging effects of free radicals.
Blueberries also contain other phytonutrients such as gallic acid, procathuic acid, caffeic acids, ferulic acids, kaempferol, quercetin, resveratrol, pterostilbene, myricetin and gallic acid. These phytonutrients provide a host of health effects, including anti-inflammatory and antioxidant effects as mentioned.
From a nutrient standpoint, blueberries also contain significant quantities of vitamin K (1 cup = 28 micrograms), manganese (1 cup = 500 micrograms), choline (1 cup – 9 mg)and vitamin C (1 cup = 14 mg). They also contain a healthy amount of fiber (1 cup = 3.6 grams).
Del Bo C, Riso P, Campolo J, Møller P, Loft S, Klimis-Zacas D, Brambilla A, Rizzolo A, Porrini M. A single portion of blueberry (Vaccinium corymbosum L) improves protection against DNA damage but not vascular function in healthy male volunteers. Nutr Res. 2013 Mar;33(3):220-7. doi: 10.1016/j.nutres.2012.12.009.
Stull AJ, Cash KC, Johnson WD, Champagne CM, Cefalu WT. Bioactives in blueberries improve insulin sensitivity in obese, insulin-resistant men and women. J Nutr. 2010 Oct;140(10):1764-8. doi: 10.3945/jn.110.125336.
McAnulty LS, Nieman DC, Dumke CL, Shooter LA, Henson DA, Utter AC, Milne G, McAnulty SR. Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running. Appl Physiol Nutr Metab. 2011 Dec;36(6):976-84. doi: 10.1139/h11-120.
Basu A, Du M, Leyva MJ, Sanchez K, Betts NM, Wu M, Aston CE, Lyons TJ. Blueberries decrease cardiovascular risk factors in obese men and women with metabolic syndrome. J Nutr. 2010 Sep;140(9):1582-7. doi: 10.3945/jn.110.124701.