The study looked at 1,628 people over the age of 60, who had normal brain function.
[Ads /]
Researchers measured the participants' levels of trans fats in their blood, as well as their overall health and diet, and followed up after 10 years.
"What they saw, was that having higher levels of trans fat in the blood, increases your risk of onset of dementia - whether it's from Alzheimer's disease as a cause of dementia - or other kinds of dementia," said Cleveland Clinic's Jagan Pillai, M.D., who did not take part in the study.
Pillai said previous research has shown that eating the Mediterranean diet, which is low in trans fats, can have a protective effect on the risk of developing dementia.
He said it's important for people to realize that trans fats are produced during industrialized food-processing methods, and have been shown to have a negative impact on heart health as well.
According to the American Academy of Neurology, trans fats were banned in the United States in 2018, with some extensions given until 2019. But the FDA has allowed foods with less than 0.5 grams of trans fats to be labeled as containing zero grams of trans fats, so some foods still contain partially hydrogenated oils.
[Ads /]
"These results give us even more reason to avoid trans fats," said the study's author Toshiharu Ninomiya, MD, PhD, of Kyushu University in Fukuoka, Japan.
"In the United States, the small amounts still allowed in foods can really add up if people eat multiple servings of these foods, and trans fats are still allowed in many other countries," Ninomiya said.
When it comes to protecting our brain health, Pillai said everything we know from research indicates eating a healthy diet, full of whole grains, fruits and vegetables, with minimal processed foods is the way to go.
"This research clearly demonstrated that your diet, and what you're putting in your body, has an impact on the onset of dementia later on in life," he said. "And many aspects that enhance your risk for onset of dementia also increase your risk for cardiovascular disease."
Complete results of the study can be found in Neurology.