State of Science :: Antioxidants
Antioxidants in Strawberries Reduce Oxidative Damage in the Brain and Can Reduce the Risk of Alzheimer's Disease
Oxidative damage to human brain cells is an inevitable part of getting older. This is because the bodys 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, as discussed in the Organic Center's recent State of Science Review entitled Elevating Antioxidant Levels in Food through Organic Farming and Food Processing (Benbrook, 2005).
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, 30 percent (Benbrook, 2005). In some crops and experiments, the differences are much more significant even greater than two-fold.
Given the importance of strawberries in the diet, the Organic Center is sponsoring research at Washington State University analyzing the differences in strawberry antioxidants and other measures of fruit quality as a function of farming systems. Results from this two-year project will be available later this year and will help determine whether organically grown strawberries might be especially good at protecting the brain from the slow and insidious degeneration triggered by oxidative stress.
Sources: 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.
Elevating Antioxidant Levels in Food Through Organic Farming and Food Processing.
Author: Charles M. Benbrook
State of Science Review, Organic Center for Education and Promotion, January 2005.