A diet high in trans fats could put you at increased risk for dementia, a new study suggests.
Most trans fats were banned in the United States last year. But foods with less than a half-gram of trans fats can be labeled as containing zero, so some foods still contain them.
The new study included over 1,600 people in Japan without dementia. Their average age was 70, and they were followed for an average of 10 years. During that time, 377 of them developed dementia.
Of the 407 who started the study with the highest levels of trans fats in their blood, 104 developed dementia, a rate of 29.8 per 1,000 person-years. (A "person-year" is a formula that accounts for the number of people in a study and how long they were followed.)
Among those with the second-highest level of trans fats, the rate was 27.6 per 1,000 person-years. The rate was 21.3 among those with the lowest trans fat levels in their blood.
After adjusting for other dementia risk factors -- such as high blood pressure, diabetes and smoking -- the researchers concluded that compared to study participants with the lowest levels of trans fats, dementia risk was 52 percent more likely among those with the highest levels.
Foods that contributed the most to high blood levels of trans fats included sweet pastries, margarine, candies and caramels, croissants, non-dairy creamers, ice cream and rice crackers, according to the study published online Oct. 23 in the journal Neurology.
"These results give us even more reason to avoid trans fats," said lead author Toshiharu Ninomiya, a professor of epidemiology and public health at Kyushu University in 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 noted in a journal news release that the World Health Organization has called for trans fats to be eliminated worldwide by 2023. "These public health efforts have the potential to help prevent dementia cases around the world, not to mention the decrease in heart disease and other conditions related to trans fats," Ninomiya said.