Regular intake of polyphenols elevates brain levels

Regular intake of polyphenols elevates brain levels

An article appearing online in advance of the publication of the September, 2009 issue of the Journal of Alzheimer's Disease revealed that regular intake of grape seed polyphenols effectively elevates plasma and brain levels of the compounds.

Polyphenols are believed to protect against the formation of beta-amyloid, a toxic protein that forms in the brains of Alzheimer's disease patients which may be responsible for some the disease's damaging effects. Earlier research had found that little, if any, polyphenols reached the brain following ingestion; however, these experiments evaluated polyphenol levels following single or sporadic dosing.

Purdue University associate professor of food science Mario Ferruzzi, in collaboration with Giulio Pasinetti, MD of Mount Sinai School of Medicine, administered three different doses of a grape seed polyphenol extract to rats by intragastric gavage.

The polyphenols gallic acid, catechin and epicatechin, and their metabolites were found in plasma in dose-dependent levels after one dose of the extract. Plasma levels measured after ten days of continual ingestion doubled in comparison with levels measured after just one polyphenol dose.

Importantly, although epicatechin and catechin were not detectable in the brains of the animals after one dose, they reached significant levels following ten days of administration. "This shows that reasonable and chronic consumption of these products may be the way to go, rather than single, high doses, similar to drugs," Dr Ferruzzi explained.

"It's like eating an apple a day, not a case of apples over two days every month."

"The most important thing is that when we follow the repetitive administration of this compound, we were able to observe the transfer of the compound to the brain," noted Dr Pasinetti, who is the Aidekman Family Professor in Neurology and director of the Center of Excellence for Novel Approaches to Neurotherapeutics.

"This may help us figure out the proper concentration necessary to get these chemicals to the brain."

Dr Ferruzzi observed that their discovery may be relevant to the delivery of other compounds and drugs. "It could become important in terms of side effects," Ferruzzi said. "You could be overdosing because the body is adapting and absorbing or metabolizing these compounds differently over time."

He added that future research will seek to determine the mechanisms that govern the absorption of compounds during chronic consumption.

Mediterranean diet : Lower risk of Alzheimer's disease, cognitive decline

Mediterranean diet: Lower risk of Alzheimer's disease, cognitive decline

Studies published in the August 12, 2009 issue of the Journal of the American Medical Association (JAMA) reveal a decreased risk of Alzheimer's disease (AD) and cognitive decline among individuals who report greater adherence to a Mediterranean type diet.

The diet includes high amounts of fruits, vegetables, legumes, cereal, fish, and monounsaturated fats, lower amounts of saturated fats, red meat and poultry, and moderate alcohol consumption.

In one article, Nikolaos Scarmeas, MD, of Columbia University Medical Center and his associates evaluated data from 1,880 elderly men and women who did not have dementia upon recruitment into the Washington Heights-Inwood Columbia Aging Project. The subjects received neurological and neuropsychological testing every 1.5 years for an average 5.4 year follow-up period, during which 282 participants were diagnosed with Alzheimer's disease.

Greater physical activity alone was associated with a lower risk of Alzheimer's disease, with a 25 percent average reduction in risk associated with some activity compared to no activity. Those who were categorized as participating in "much" physical activity experienced a 33 percent average lower risk.

When adherence to a Mediterranean diet was considered, those in the middle third of participants had an average 2 percent reduction in the risk of developing Alzheimer's disease, while those in the top third had experienced a 40 percent reduction compared to those in the lowest third.

Having both high levels of physical activity and adherence to the diet were also associated with a protective benefit. “Compared with individuals with low physical activity plus low adherence to a diet, high physical activity plus high diet adherence was associated with a 35 percent to 44 percent relative risk reduction," the authors write. “In summary, our results support the potentially independent and important role of both physical activity and dietary habits in relation to AD risk.”

In a second study published in the journal, greater adherence to a Mediterranean diet was associated with a reduction in cognitive decline.

Catherine Féart, PhD, of the Université Victor Ségalen in Bordeaux, France, and colleagues evaluated data from 1,410 participants aged 65 years and older in the Three-City cohort, a study of vascular risk factors and dementia. Participants were assessed for cognitive performance during 2001-2002 and were re-examined at least once over the following 5 years.

Dietary questionnaires were scored from 0 to 9 for Mediterranean diet adherence.
Although greater adherence to the diet was associated with fewer errors over time on one neuropsychological test, indicating a reduction in cognitive decline, the risk of developing dementia was not associated with diet adherence.

“A variety of approaches to mitigating cerebrovascular disease in midlife exist, including diet, exercise, treatment of hypertension, treatment of diabetes, avoidance of obesity, and avoidance of smoking," writes David S. Knopman, MD, of the Mayo Clinic in an accompanying editorial.

"The findings of Scarmeas et al and Féart et al fit into a larger and potentially optimistic view of prevention of late-life cognitive impairment through application, at least by midlife, of as many healthy behaviors as possible, including diet. Based on these 2 studies, diet may play a supporting role, but following a healthy diet does not occur in isolation.”