Oxidative damage to human brain cells is an inevitable part of getting older. This is because the body’s natural antioxidant defense mechanisms become steadily less efficient as we age. For this reason, the consumption of foods high in antioxidant content is increasingly important among the elderly, see Antioxidants for more information.

Scientists at Cornell University carried out a sophisticated analysis of the impact of the antioxidants in strawberries, bananas, and oranges on oxidative stress and damage. They used three bioassay systems developed to study oxidative stress-induced neurotoxicity (Heo and Lee, 2005). The antioxidants in strawberries reduced oxidative damage in a dose-dependent manner, and at the highest concentration tested (2,000 micrograms per milliter), largely prevented oxidative damage. Strawberry phenolics also helped reduce damage to the cell membranes in the brain, which are known to be exceptionally sensitive to oxidative stress.

The total phenolic levels in the three fruits were reported in gallic acid equivalents (GAE, a widely studied antioxidant). Strawberries contained 155 milligrams of GAE per 100 grams of fresh weight, compared to 100 for bananas and 91 for oranges. But in the case of the important anthocyanins, strawberries contained by far the highest concentration – 19.4 milligrams of cyanidin 3-glucoside per 100 grams of fresh weight, compared to 0.005 and 0.01 milligrams in the case of bananas and oranges.

The relatively few well-designed studies comparing antioxidant levels in fruit and vegetables grown under organic and conventional farming systems suggests that organic farming increases antioxidant levels, on average, about 20 percent. In some crops and experiments, the differences are much more significant – even greater than two-fold. See the 2015 British Journal of Nutrition meta-analysis on plant-based foods for more on this.

Source: “Strawberry and Its Anthocyanins Reduce Oxidative Stress-Induced Apoptosis in PC12 Cells.”
Authors: Ho Jin Heo and Chang Yong Lee.
Journal of Agricultural and Food Chemistry, Volume 53, Number 6, March 23, 2005.