Female mice that followed the food regime — popular with Kourtney and Kim Kardashian — saw particular benefits to their memory, US researchers found.
Mice put on the low-carb diet had nearly seven times the levels of a molecule called beta-hydroxybutyrate (BHB), which plays a pivotal role in preventing early memory decline.
Dr Gino Cortopᴀssi, of the University of California, Davis, said: “The ketogenic diet in general, and BHB specifically, delays mild cognitive impairment and it may delay full blown Alzheimer’s disease.”
Professor Izumi Maezawa, of UC Davis, added: “We observed amazing abilities of BHB to improve the function of synapses, small structures that connect all nerve cells in the brain. 
“When nerve cells are better connected, the memory problems in mild cognitive impairment are improved.”
Around 944,000 Brits are living with dementia now, but experts predict this figure will grow over time, with more than one million living with dementia at the end of the decade.
Alzheimer’s disease is the most common form of the condition and is thought to be caused by build-ups of proteins in the brain, including tau and amyloid.
There is currently no cure for the disease, although promising drugs to slow down its progress are currently in trials.
Cognitive impairment is a medical term used to describe when a person has trouble remembering, learning new things, concentrating, or making decisions that affect their everyday life.
People often experience cognitive decline before they are diagnosed with Alzheimer’s disease or dementia.
The keto diet is an eating protocol that involves swapping out carb-heavy foods like potatoes and pasta for higher fat ones like fish, eggs and avocados.
Michelle Routhesnstein, registered dietician and nutritionist at EntirelyNourished.com, told MedicalNewsToday: “A ketogenic diet is a high fat, low-carbohydrate eating approach that causes ketosis.
“Ketosis is a metabolic state where the body primarily burns fat for fuel instead of carbohydrates, which yields ketone bodies as an alternative energy source.”
Previous research has shown mice that were put on the diet lived around 13 per cent longer than those that followed regular eating patterns.
The latest study, published in Nature Communications Biology, looked at how it impacts the early stages of Alzheimer’s-related memory loss.
Mice were given either a keto diet or carbohydrate rich diet with the same number of calories for seven months.