We don't know how to cure Alzheimer's disease yet, but scientists are learning more about what increases or decreases our risk of developing it – and one of those risk factors seems to be the diet we've become accustomed to in the Western world.

A new review of 38 previous studies from the last five years identifies the Western diet pattern as a risk factor for developing Alzheimer's in mild-to-moderate cases of the disease.

On the other hand, the Mediterranean diet, the ketogenic diet, and diet supplementation with omega-3 fatty acids and probiotics appear to protect against the disease, but only in those mild-to-moderate cases.

Researchers from several institutions in China propose that dietary changes could be one way of reducing the risk of developing Alzheimer's and other types of dementia and limiting the damage it does to our cognitive abilities.

"Certain nutritional interventions may slow the progression of Alzheimer's disease and improve cognitive function and quality of life," write the researchers in their published paper.

In the studies analyzed, these "nutritional interventions" improved cognitive function and quality of life for those with mild-to-moderate Alzheimer's. They also seemed to slow down the progression of the disease.

While we don't know what causes Alzheimer's, we do know that it causes the build-up of amyloid-beta (Aβ) peptides and tau protein clumps in the brain, leading to the breaking down of neurons key to thinking and remembering.

Based on the research, the way that dietary choices affect inflammation could be key here: Western diets high in saturated fat, sugar, and salt might be putting our bodies under extra stress, which somehow makes us more vulnerable to dementia.

"The main mechanisms are based on the reduction of oxidative stress and inflammation and a lower accumulation of Aβ peptides," write the researchers.

The Mediterranean diet is high in whole grains, fruits, vegetables, and seafood, while the ketogenic diet is a very specific, high-fat, low-carbohydrate approach to eating. As the researchers note, the keto diet is not without risk in terms of overall health and should be used in consultation with a doctor.

Dementia is thought to affect more than 50 million people worldwide as of 2020, and that number is climbing steadily. Figuring out ways of reducing risk while the search for a cure goes on could make a significant difference.

The work goes on to understand how diet is linked to Alzheimer's disease and the mechanisms at play – but this study and others like it are helping to give scientists a more precise picture of how what we eat affects the brain.

"The results showed that nutritional interventions are capable of slowing down the rate of progression of Alzheimer's disease, improving cognitive function, and improving the quality of life of these patients," write the researchers.

"However, many knowledge gaps remain to be investigated; therefore, a deeper study on the association between nutrition and Alzheimer's disease is recommended."

The research has been published in Frontiers in Neuroscience.