Researchers from Edith Cowan University in Western Australia examined the diets of 541 Australians and measured the levels of amyloid beta (A) in their brain, which is a precursor to Alzheimer's disease.
They found that participants with higher levels of protein in their diet were less likely to have high levels of A in their brain, reducing their risk of developing Alzheimer's disease.
The participants were divided into three groups based on their protein intake.
The team found that those with the highest consumption, around 118 grammes per day, were 12 times less likely to have high levels of A than those in the lowest consumption group, who ate only 54 grammes per day.
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"The research clearly demonstrates that the more protein eaten the lower the chances someone has of having a high A burden on the brain, which corresponds to a lower risk of developing Alzheimer's in the future, she said.
Fernando said it was still unknown what was driving the relationship between high protein intake and low A.
One possibility is that previous studies have shown that a high protein diet is associated with lower blood pressure, she said.
She said the next step was to further examine what role gender, genetics, age and metabolic factors play in the relationship between protein consumption and Alzheimer's disease.
Protein is found in animal products like beef, pork, lamb, eggs, fish and poultry, as well as in plant-based foods like legumes, whole grains, nuts and seeds.
To get the protective effect that we have demonstrated, you need to be eating about 120 grammes of protein each day, which is not too hard, Fernando said.