Phenolic compounds seem particularly effective in terms of keeping nitric oxide within the correct range, thus improving circulation and reducing free-radical damage from nitrogen peroxides. Another important property of flavonoids is their ability to raise the levels of glutathione. Glutathione is arguably the most important neuroprotector, being not only our primary antioxidant defense, but also an effective suppressor of chronic inflammation, known to be a significant factor in all the major diseases related to aging. Victims of Parkinson's disease show low levels of glutathione in brain tissue. It's interesting to speculate that perhaps compounds that raise glutathione, such as lipoic acid, NAC, and the potent phenolics found in berries, cherries and walnuts, might be able to help prevent the development of Alzheimer's disease and Parkinson's disease, two of the most feared and disabling degenerative disorders of old age.
Flavonoids also tend to lowerblood sugar, and thus glycation.
An extract of blueberry leaves has been a traditional folk remedy against diabetes. In addition, bilberry extract has been shown to enhance the blood-brain barrier, which tends to become impaired with aging, showing a decrease in vascular density, increased permeability and other abnormalities. The normal functioning of blood-brain barrier is important not only for keeping out toxins and undesirable compounds, but also for glucose transport to the brain. Animal studies have also shown that if the blood-brain barrier becomes damaged and too permeable, anthocyanins help restore normal permeability. The public became interested in bilberry extract after the news about its vision-improving benefits.