The silicon content of beer may protect against the deleterious effects of aluminium on brain health, suggests a new study with mice from Spain.
The research taps into beer's silicon content, and reports that moderate consumption cut the uptake in the digestive tract of aluminium, a neurotoxin and recently linked as a possible causal factor for Alzheimer's.
The study, published in the journal Food and Chemical Toxicology, reports that "moderate beer consumption… could perhaps be taken into account as a component of the dietary habits of the population."
The researchers from the University of Alcala in Madrid state however that "alcoholic beverage consumption needs to be kept within certain limits depending both on gender and on age and should never be promoted as a means of increasing certain nutrients, which can be obtained from other foodstuffs in the diet."
Mice were divided into four groups, with three groups receiving aluminium nitrate in their drinking water. The first of these groups also received 2.5 ml of commercial beer (5.5 per cent alcohol) per week, the second received a 2.5 ml solution of silicic acid per week, while the third group received no silicon supplement (positive control). The fourth group received aluminium-free drinking water (negative control).
After three months the researchers report that animals receiving the supplementary silicon, whether from beer or the silicic acid, had significantly lower blood aluminium levels, and higher faecal excretion of aluminium.
The lower blood levels resulted in slower accumulation of aluminium in the tissue, including the brain, which could have benefits for the prevention of Alzheimer's, suggested the researchers.
Alzheimer's disease is the most common form of dementia and currently affects over 13 million people worldwide. The direct and indirect cost of Alzheimer care is over $100bn (€ 81bn) in the US alone. The direct cost of Alzheimer care in the UK was estimated at £15bn (€ 22bn).
They also note that, despite the silicic acid supplement providing double the amount of silicon as found in beer, no significant differences in blood silicon levels were observed between the two supplemented groups.
"Thanks to the potential interaction observed between aluminium and silicon in the digestive tract and lower concentrations of aluminium in the blood and brain tissue, it appears that silicon in the form of silicic acid may lower the bioavailability of aluminium, and hence silicon should be regarded as a factor that may afford protection against aluminium, reducing therefore, one of the risk factor for Alzheimer's disease," wrote the researchers.
"These result are in agree with the epidemiology study achieved by Gillette-Guyonnet et al. (2005), who conclude that silica in drinking water may reduce the risk of development Alzheimer's disease in elderly women."
Previously, the potential health benefits of beer have focussed on the flavonoid xanthohumol found in hops. Research has suggested that the compound could help prevent prostate cancer, but the scientists suggest supplements rather than beer for exploiting the potential benefits.
Source: Food and Chemical Toxicology
January 2008, Volume 46, Issue 1, Pages 49-56
"Role of beer as a possible protective factor in preventing Alzheimer's disease"
Authors: M.J. Gonzalez-Munoz, A. Pena and I. Meseguer
"Alzheimer disease is a progressive neurodegenerative disease characterized clinically by progressive cognitive impairment. Pathological hallmarks of Alzheimer disease in the brain include intracellular neurofibrillary tangles and deposits of aggregated amyloid-Beta protein (A-Beta) in neuritic plaques and cerebral vessels. The authors in this study did not measure any of the biological markers that one can truly show that Alzheimer disease is influence by aluminum.
"While we agree that the pathogenic mechanisms that lead to the development of Alzheimer, however, are not fully understood, it is for this reason that the Beverage industry should not seek to bring about publicity to studies that do not substantially tell us anything novel or compelling.
"The question as to how much beer to consume in order to get the desired amount of silicon comparable to the amount fed to mice, weight for weight remains in the back of our minds.
"Rather than use regular mice, the APP/PS1 double transgenic mice, which are an established model of Alzheimer in humans, would have been the appropriate model"
Thomas Fungwe, Ph.D.
Nutrition Policy Analyst, Center for Nutrition Policy and Promotion, United States Department of Agriculture, Alexandria, Virginia, USA
& Adjunct Professor of Nutrition, Prince George's Community College, Largo, Maryland, USA
These comments are personal and are based on Dr. Fungwe's research/professional experience and scientific knowledge, and do not represent the views of his employer or anyone else.