People who eat the highest amounts of ultra-processed foods like soft drinks, chips and cookies may have a higher risk of developing dementia than those who eat the lowest amounts, according to a new study published in the online issue of Neurology®, the medical journal of the American Academy of Neurology. Researchers also found that replacing ultra-processed foods in a person’s diet with unprocessed or minimally processed foods was associated with a lower risk. The study does not prove that ultra-processed foods cause dementia. It only shows an association.
Ultra-processed foods are high in added sugar, fat and salt, and low in protein and fiber. They include soft drinks, salty and sugary snacks, ice cream, sausage, deep-fried chicken, yogurt, canned baked beans and tomatoes, ketchup, mayonnaise, packaged guacamole and hummus, packaged breads and flavored cereals.
“Ultra-processed foods are meant to be convenient and tasty, but they diminish the quality of a person’s diet,” said study author Huiping Li, PhD, of Tianjin Medical University in China. “These foods may also contain food additives or molecules from packaging or produced during heating, all of which have been shown in other studies to have negative effects on thinking and memory skills. Our research not only found that ultra-processed foods are associated with an increased risk of dementia, it found replacing them with healthy options may decrease dementia risk.”
Participants of the study were age 55 and older and did not have dementia at the start of the study. They were followed for an average of 10 years. By the end of the study, 518 people were diagnosed with dementia.
During the study, participants filled out at least two questionnaires about what they ate and drank the previous day. Researchers determined how much ultra-processed food people ate by calculating the grams per day and comparing it to the grams per day of other foods to create a percentage of their daily diet. They then divided participants into four equal groups from lowest percentage consumption of ultra-processed foods to highest.
After adjusting for age, gender, family history of dementia and heart disease and other factors that could affect risk of dementia, researchers found that for every 10% increase in daily intake of ultra-processed foods, people had a 25% higher risk of dementia.
Researchers also used study data to estimate what would happen if a person substituted 10% of ultra-processed foods with unprocessed or minimally processed foods, like fresh fruit, vegetables, legumes, milk and meat. They found that such a substitution was associated with a 19% lower risk of dementia.
“Our results also show increasing unprocessed or minimally processed foods by only 50 grams a day, which is equivalent to half an apple, a serving of corn, or a bowl of bran cereal, and simultaneously decreasing ultra-processed foods by 50 grams a day, equivalent to a chocolate bar or a serving of fish sticks, is associated with 3% decreased risk of dementia,” said Li. “It’s encouraging to know that small and manageable changes in diet may make a difference in a person’s risk of dementia.”
Li noted that further research is needed to confirm the findings. A limitation of the study was that cases of dementia were determined by looking at hospital records and death registries rather than primary care data, so milder cases may have been overlooked. The study was funded by the National Natural Science Foundation of China.
Learn more about dementia at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.