Cashew nuts are a rich source of polyphenols, and a study published in the Journal of Nutritional Biochemistry suggests that they might boost the risk for dementia.
The findings could help develop new treatments for people with dementia, but researchers at the University of Auckland in New Zealand were particularly interested in whether the nuts could increase the brain’s levels of the polyphenol, which are believed to be linked to cognitive impairment.
“We wanted to see whether there were differences in the brains of people with a history of cognitive impairment,” said lead author, Associate Professor Kate Stapleton.
“I was really curious to see if there were any differences in our results with people with cognitive impairment.”
The team had a sample of 25 people with moderate to severe dementia who were assessed using a battery of cognitive tests to determine whether they were cognitively impaired.
“The first thing we did was to look at the brains,” said Associate Professor Stapton.
“And we were actually surprised to find that the people with the most severe cognitive impairment, we had the highest levels of polyphosphate, a marker of brain inflammation, which is associated with dementia.”
The researchers then compared the brain micrographs of the people who had a history, with the people without.
“It’s very interesting to see that in the absence of a history people with mild cognitive impairment showed the most increased levels of inflammatory biomarkers, and people with severe cognitive impairments showed the least,” said Dr. Michael J. Mears, the study’s first author.
“This is a big surprise.”
The findings showed that the participants with mild-to-moderate cognitive impairment were at higher risk of developing dementia than those with severe dementia, even after controlling for other risk factors, such as smoking, obesity, and the amount of alcohol consumed.
“These are people who may be at a higher risk than those who are at a lower risk, but who are still getting the benefit from the nuts,” Dr. Mear added.
The researchers believe that the polyphosomes present in nuts can be transferred to the brain from the intestines.
“You know, if you are getting a nut in the colon, it might be transferring from the intestine to the colon,” Associate Professor Mears said.
“In the intestine, polyphusins are metabolised by the gut bacteria, and then transferred into the brain.”
“We’re looking at the role that the gut microbiota plays in the brain, and how the microbiota might influence the development of dementia.”
There are several types of nuts in the world, but there is no specific genetic gene for the nuts, which means they can be made from a variety of plants.
There are no studies that have directly linked a person’s risk of a disease with the type of nut they eat, but the researchers hope their findings can help develop treatments for those with dementia.
“There is a lot of controversy around how much nut consumption we should be consuming, but in this case, there is evidence that the evidence suggests that consuming nuts might be helpful for dementia risk reduction,” Dr Mears added.