Recent evidence suggests that polyphenols, the most abundant dietary antioxidants, provide strong neuroprotection against oxidative damage linked to the development of Alzheimer’s disease. It has been shown that most polyphenols are primarily found in the outer sections of fruits and vegetables and thus the concentrations of these antioxidants are frequently affected by food preparation.
Dai et al. (2006) analyzed consumption of fruit and vegetable juices as a potential dietary source of polyphenols. Commercial fruit and vegetable juices are usually prepared using concentrates that include the peel and pulp, and thus have high concentrations of polyphenols.
The researchers looked at a cohort of about 1200 Japanese Americans in King County, Washington, following this population for nine years. They found that “the risk for probable Alzheimer’s disease was significantly reduced among people who drank fruit and vegetable juices…three or more times per week, compared with those who drank these juices less than once per week.”
This study suggests that this benefit occurs because the polyphenols from juices, such as quercetin from apple juice, cross the blood-brain barrier and provide neuroprotection from hydrogen peroxide (H2O2). It appears that the oxidative damage caused by the β-amyloid peptide in the pathogenesis of Alzheimer’s is H2O2 mediated. Antioxidant rich fruit and vegetable juices may be an important way to protect against this degenerative process.
This study represents the first time a link between juice consumption and Alzhemier’s rates has been shown. The researchers conclude that their findings “suggest that fruit and vegetable juices may play an important role in delaying the onset of Alzheimer’s disease.”
Authors: Qi Dai, Amy Borenstein, Yougui Wu, James C. Jackson, and Eric B. Larson,
The American Journal of Medicine, Volume 119, Number 9, September 2006.