Eating a keto diet prevented the mild cognitive impairment that's often seen in the early stages of Alzheimer’s disease by altering the way brain cells connect and communicate, new research has found. The researchers suggest that adopting the diet may be a way of delaying the onset of full-blown Alzheimer's.
Despite its hype, the low-carb, high-fat, moderate protein ketogenic or keto diet remains somewhat controversial. In the ‘pros’ column, studies have found that keto may extend lifespan, protect against epileptic seizures, and enhance chemotherapy treatments. As far as its ‘cons,’ nutritionists have argued that long-term the diet is fundamentally unhealthy, and it’s been found to contribute more to climate change than other diets.
The findings of a new study by researchers at the University of California, Davis (UC Davis) would most likely be considered a ‘pro.' The researchers found that, at least in mice, eating a keto diet significantly delayed the mild cognitive impairment usually seen in the beginning stages of Alzheimer’s disease by increasing levels of the molecule beta-hydroxybutyrate (BHB).
“The data support the idea that the ketogenic diet in general, and BHB specifically, delays mild cognitive impairment, and it may delay full-blown Alzheimer’s disease,” said Gino Cortopassi, one of the study’s corresponding authors. “The data clearly don’t support the idea that this is eliminating Alzheimer’s disease entirely.”
The keto diet started life in 1921 as a way of suppressing epileptic seizures, and although its mechanism of action remains a mystery, it’s still a treatment option for juvenile epilepsy, especially when seizures are resistant to treatment. More recently, it’s been explored as a way of boosting cognitive functioning and alleviating the symptoms of neurodegenerative disorders like Parkinson’s disease and ALS.
The goal of the diet is to shift from using glucose as the body’s main fuel source to burning fat for energy. When the glucose supply is too low for the body’s energetic needs – which is what happens with the keto diet, given the very small amounts of glucose-giving carbs eaten – the liver breaks down fatty acids into ketones, including BHB. Most organs and tissues, including the brain, can use ketones as an alternative source of energy.
In the current study, the researchers expanded on their previous research, which found that mice lived 13% longer when they ate a keto diet, to see how mouse brains responded to going keto. They fed mouse models of Alzheimer’s disease a ketogenic diet for seven months and assessed cognitive memory and synaptic plasticity, the ability of the place where neurons connect and communicate to change its structure and/or function.
After being fed a keto meal, circulating BHB levels were significantly increased in both male and female mice compared to the control group. In a fasting state, BHB levels were higher than in the fed state and significantly higher in females.
“If these results translated to humans, that could be interesting since females, especially those bearing the APOE4 gene variant, are at significantly higher risk for Alzheimer’s,” Cortopassi said.
When the researchers examined the brains of the keto-fed mice, they found the brain’s memory storage mechanism had been significantly ‘rescued.' Genes relating to synaptic plasticity were upregulated, but there was no reduction in beta-amyloid plaques, a hallmark pathology in Alzheimer’s disease. This suggested that the diet’s – or BHB’s – mode of action was to rescue cognitive function and memory by improving synaptic plasticity.
“We observed amazing abilities of BHB to improve the function of synapses, small structures that connect all nerve cells in the brain,” said Izumi Maezawa, the study’s other corresponding author. “When nerve cells are better connected, the memory problems in mild cognitive impairment are improved.”
BHB is available to purchase as a dietary supplement. The researchers caution that, at this stage, BHB’s effect on mouse memory and cognitive functioning has yet to be confirmed, so it’s probably not worth buying BHB in bulk just yet. While ketone supplements are generally considered safe, they can produce side effects like nausea, diarrhea, and stomach pain. And the ketones they contain are often bound to salt – sodium, potassium, calcium, or magnesium – so consuming too much is not recommended.
The study was published in the journal Communications Biology.
Source: UC Davis