American Academy of Neurology:https://www.aan.com/PressRoom/Home/PressRelease/2753
MINNEAPOLIS – People who have more trans fats in their blood may be more likely to develop dementia years later, according to a study published in the October 23, 2019, online issue of Neurology®, the medical journal of the American Academy of Neurology. Trans fats, also known as trans fatty acids, are industrially produced and found in food with partially hydrogenated vegetable oils. They also occur naturally in small amounts in certain meat and dairy foods.
Trans fats were banned in the United States in 2018, with some extensions given until 2019. However, the Food and Drug Administration (FDA) 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.
“These results give us even more reason to avoid trans fats,” said study 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.”
The study found that people with higher levels of trans fats in their blood were 50 to 75 percent more likely to develop Alzheimer’s disease or dementia years later than people with lower levels of trans fats in their blood.
The study involved 1,628 people living in a Japanese community with an average age of about 70 who did not have dementia. The level of trans fats from industrial-produced sources in the participants’ blood was measured at the beginning of the study, and they were divided into four groups based on those levels. Participants were also given a questionnaire about how often they ate certain foods.
Then they were followed for an average of 10 years. During that time, 377 people developed dementia.
Of the 407 people with the highest level of trans fats, 104 developed dementia, or an incidence rate of 29.8 per 1,000 person-years. For people with the second-highest level of trans fats, 103 of the 407 developed dementia, for an incidence rate of 27.6 per 1,000 person years. Of the 407 people with the lowest level, 82 developed dementia, an incidence rate of 21.3 per 1,000 person-years.
After adjusting for other factors that could affect the risk of dementia, such as high blood pressure, diabetes and smoking, researchers found that those in the highest group were 52 percent more likely to develop dementia than those in the lowest group, while those in the second-highest group were 74 percent more likely to develop dementia than the lowest group.
The researchers also looked at which foods contributed the most to high levels of trans fats in the blood. Sweet pastries were the strongest contributor, followed by margarine, candies and caramels, croissants, non-dairy creamers, ice cream and rice crackers.
“The World Health Organization has called for trans fats to be eliminated worldwide by 2023,” Ninomiya said. “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.”
A limitation of the study was that participants’ level of trans fat in the blood was measured only at the beginning of the study. In addition, all of the participants were from the same town in Japan, and levels of trans fats in the diet vary by country, region and time period, so the results may not apply to other populations.
The study was supported in part by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the Japanese Ministry of Health, Labor and Welfare and the Japan Agency for Medical Research and Development.