Eating grapes on a regular basis slows metabolic decline of the brain in Alzheimer's sufferers, a small-scale study done in California indicates.
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A grape a day won't do it. The pilot study fed grape powder equivalent to two-plus cups of grapes a day for six months, to Alzheimer's patients defined with a mild decline in cognition. Result: the fruit protected against the decline of metabolic activity in the test group given grape powder. The ones who did not eat grapes did exhibit deterioration of brain metabolism in the six-month trial period.
Note that the results relate to brain metabolism, not cognition. "No significant differences were seen in scores on the neuropsychological battery of tests between the two groups," the scientists stress.
"The study examines the impact of grapes as a whole fruit versus isolated compounds," explains Dr. Daniel H. Silverman, lead investigator of the study. "The results suggest that regular intake of grapes may provide a protective effect against early decline associated with Alzheimer's disease."
The results were published in the Experimental Gerontology paper, "Examining the impact of grape consumption on brain metabolism and cognitive function in patients with mild decline in cognition".
The grapes proved beneficial not only to areas of the brain affected by Alzheimer's, but to areas associated with attention and working memory performance too. Again, comparison is to comparable people who weren't stuffed with grapes, or rather with whole grape powder.
Low metabolic activity in these areas of the brain is a hallmark of early-stage Alzheimer's disease, an incurable and irreversible neurodegenerative condition whose symptoms can be treated, at this stage, but not reversed (in humans: a genetic study done in mice last year reported symptom reversal).
The writers themselves note that more work needs to be done before subscribing to a grape delivery service. Their sample included ten people, five of them women, with a mean age of 72, who had been diagnosed with mild decline in cognition.
Cognitive performance was measured through neuropsychological assessments performed at baseline and 6 months after initiation of therapy. Changes in brain metabolism were assessed by injecting the patients with radiotracer material and scanning their brains.
The scientists note that a growing body of evidence shows that grapes do good things for the nervous system -, and for cardiovascular health as well. Similar work has shown that consuming grapes, its products and certain wines, is associated with lower risk for cardiovascular disease.
How the grape achieves all these things is not clear, though people have believed in the medical properties of the fruit for thousands of years, for instance in ancient Egypt, and not only because they'd had too much wine.
Wine appears to be confer more benefit than other alcoholic beverages, write the scientists in a seminal 2009 paper "Grapes and Cardiovascular Disease" Some think the benefit of the grape, and berries and some other foods, lies in their polyphenols, which are natural antioxidants that help combat inflammatory conditions.
A 2014 study pointed at flavonoids as being the responsible chemical for the upside that eating grapes and berries has for the cardiovascular system.
Most likely the grapes are having multiple effects. As broader clinical studies are done on larger groups of subjects, we may find out.