People who eat a pack of popcorn a day may be less likely to suffer from dementia, a study suggests.
Researchers at Rush University in Chicago made the discovery after tracking 3,300 people for six years and testing their cognition.
They found those who ate three ounces or more of whole grains — such as lightly salted popcorn, quinoa or cereal — a day had a smaller reduction in their cognitive scores compared to those who barely ate the foods.
Researchers only observed the effect in black participants, who made up 60 percent of the study participants.
They may not have seen the same in white participants because there were too few in the study or because they were much less likely to eat whole grains overall than their peers.
Researchers at Rush University in Chicago made the discovery after tracking 3,300 people for six years and testing their cognition twice (stock image)
Whole grains are very high in fiber, which slows the uptake of sugar into the bloodstream.
This prevents sugar spikes, which can cause plaque in the arteries and inflammation which increases the risk of dementia.
It comes after researchers also found eating just one bowl of frosted flakes per day could raises the risk of mouth and throat cancer by as much as 25 percent.
More than six million Americans have dementia, but this figure is expected to more than double over the next two decades.
Older black adults are more than twice as likely to be diagnosed with the condition, which experts say may be linked to the group having higher rates of heart disease.
For the study, published today in Neurology, scientists analyzed data from 3,300 adults who were 75 years old on average and did not have dementia.
They had all taken part in the Chicago Health and Aging Project, which tracked 10,000 people from 1993 to 2012
They were surveyed every three years on how often they ate whole grains and were also asked to complete cognitive and memory tests.
These included tasks such as having to recall a list of words, remember numbers and put them back into the correct order.
Participants were then divided into five groups based on how many whole grains they had consumed and their cognitive scores were compared.
This was from a group where adults consumed less than half a serving — or half an ounce — of whole grains per day up to those who consumed three servings or more.
Dietary Guidelines for Americans recommend at least three servings of whole grain foods per day, with one serving being equivalent to one ounce — such as a slice of bread or half a cup of cooked pasta or rice.
After adjusting for factors such as age, sex, education and smoking, researchers found that those eating three or more whole grains per day had a slower rate of cognitive decline than those who ate the least.
Cognitive decline is an early hallmark for dementia.
They also found black participants were more likely to eat more whole grains than white participants.
Out of black participants, 68 percent reported eating more than one serving of whole grains per day. For comparison, among white participants this dropped to 38 percent.
Researchers were not certain why eating whole grains reduced the risk of dementia, but they said this could be linked to how it helps to regulate blood sugar or promote a healthy gut.
This would help to reduce the risk of inflammation and damage to the blood vessels, they said, which may raise the risk of developing dementia.
People who eat whole grains are also more likely to observe a healthy lifestyle, such as sleeping or exercising more, which also help reduce the risk of dementia.
The study was observational and could not prove that eating popcorn alone reduced the risk of dementia.
It also did not consider toppings put on popcorn, such as butter and sugar, which may raise the risk of dementia by raising the risk of obesity.
Limitations of the study include diets were self-reported, with participants not required to submit evidence for what whole grains they consumed.
Dr Xiaoran Liu, an epidemiologist who led the research, said: ‘With Alzheimer’s disease and dementia affecting millions of Americans, finding ways to prevent the disease is a high public health priority.
‘It’s exciting to see that people could potentially lower their risk of dementia by increasing their diet of whole grains by a couple of servings a day.’