High protein diets may shrink brain and boost risk of Alzheimer's

High-protein diets may shrink the brain as well as the waistline, raising the risk of Alzheimer's disease in later life.

In tests, the brains of mice fed Atkins-like diets, rich in protein and low in carbohydrate, were five per cent lighter than those of other creatures.

Importantly, areas key to memory were underdeveloped.

High protein diets could be bad for the brain

Although it is unclear if high protein diets have the same effect in people, it is already known that low-fat diets packed with fruit and vegetables, cut the risk of dementia.

The US researchers said that looking at how different nutrients affect human brain health could lead to new ways of staving off the disease that affects 400,000 Britons.

With the number of sufferers expected to double within a generation, any method of cutting the number of cases could have a huge impact on public health.

Sam Gandy, a leading expert on Alzheimer's disease, looked at the effect of various diets, including one high in protein and low in carbohydrate on the brains of mice.

The creatures had been genetically-engineered to make amyloid-beta, the poisonous plaques blamed for brain cell death and memory loss in Alzheimer's.

Those given high-protein foods had lighter brains than other animals, the journal Molecular Neurodegeneration reports.

Interestingly, they did not have more plaques than the other animals.

It is thought that large amounts of protein may make the brain more vulnerable to the poisonous effect of the plaques, speeding up cell death.

Dr Gandy, of the Mount Sinai School of Medicine in New York, says research into the effects of protein on people is now vital.

'This would be a challenging undertaking but potentially worthwhile if there is a real chance that the ravages of Alzheimer's disease might be slowed or avoided through healthy eating,' he said.

'Such trials will be required if scientists are ever to make specific recommendations about dietary risks for Alzheimer's disease.

'We know that obesity in middle life can increase the risk of Alzheimer's later even if the excess weight is lost by late life, so we will need to do more experiments in mice and in humans to determine when the "window of vulnerability" might be open.'

The Alzheimer's Society welcomed the research but questioned whether the use of GM mice had skewed the results.

Dr Susanne Sorensen, the charity's head of research, said: 'Further investigation is now needed to better understand whether the way we balance our diet can increase or reduce our vulnerability to Alzheimer's disease.

'It is important to eat a diet rich in fruit, vegetables and fish. People who want to reduce their risk of dementia should also take regular exercise, refrain from smoking and get their blood pressure and cholesterol checked.’

The Atkins diet, which promoted swapping white bread and potatoes for fry-ups and steaks, was followed by three million Britons at the height of its popularity.

However, the eating plan fell out of favour after being dogged by side-effects such as constipation and mood-swings and allegations that it could increase the risk of heart disease and kidney problems.

Dieticians also warned that people find it hard to stick to the restrictive diet plan, quickly putting back on any weight they'd lost.