Researchers observing the effects of various diets on the brains of genetically engineered mice bred for studying Alzheimer’s disease found quite unexpectedly that mice fed a high protein, low carbohydrate diet, developed brains that were five per cent lighter than those of mice fed other diets.
The study was the work of lead author, Sam Gandy, a professor at The Mount Sinai School of Medicine in New York City and a neurologist at the James J Peters Veterans Affairs Medical Center in the Bronx NY, and colleagues from research centers in the US, Canada, Australia and the UK. The study is published this week in BioMed Central’s open access journal Molecular Neurodegeneration.
Many other studies have already suggested that low calorie, low fat diets rich in vegetables, fruits, and fish may delay or slow down Alzheimer’s disease, so Gandy and colleagues decided to take this a step further and compare the effects of several different diets on mice that were genetically engineered to have some of the disease characteristics of Alzheimer’s.
Alzheimer’s is a brain-wasting disease where the cerebral cortex shrinks, and microscopic beta-amyloid plaques form around neurons or brain cells and neurofibrillary tangles form inside them.
Beta amyloid is a protein fragment snipped from an amyloid precursor protein (APP), whose role in the brain is not fully understood. What we do know is that in a healthy brain, beta amyloid fragments are broken down and eliminated, but in Alzheimer’s disease, they build up and form hard, insoluble plaques.
For the study, Gandy and colleagues tested four different diets on mice that were genetically engineered to express a mutant form of APP.
For 14 weeks (from the age of 4 weeks until 18 weeks) they fed the male and female mice on one of four diets: (1) a regular (reference) diet; (2) a high fat/low carbohydrate diet (60 per cent fat, 30 per cent protein, 10 per cent carbs, by calorie value); (3) a high protein/low carbohydrate diet (60 per cent protein, 30 per cent fat, 10 per cent carbohydrate by calorie value); or (4) a high carbohydrate/low fat diet (60 per cent carbohydrate, 30 per cent protein, 10 per cent fat, by calorie value).
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