High intake of ultra processed foods linked to early signs of Parkinson's

People who eat more ultra processed foods like cold breakfast cereal, cookies and hot dogs are more likely to have early signs of Parkinson's disease when compared to those who eat very few ultra processed foods, according to a study published in the May 7, 2025, online in Neurology^®, the medical journal of the American Academy of Neurology. The study does not prove that eating more ultra processed foods causes early signs of Parkinson's disease; it only shows an association.

Researchers looked for signs of prodromal Parkinson's disease, which is the earliest stage, when neurodegeneration begins, but more characteristic symptoms of Parkinson's disease, like tremors, balance problems and slow movement, have not yet begun. These early symptoms can begin years or even decades before the typical symptoms start.

Eating a healthy diet is crucial as it has been associated with a lower risk of neurodegenerative diseases and the dietary choices we make today can significantly influence our brain health in the future. There's growing evidence that diet might influence the development of Parkinson's disease. Our research shows that eating too much processed food, like sugary sodas and packaged snacks, might be speeding up early signs of Parkinson's disease."

Xiang Gao, MD, PhD, study author of Institute of Nutrition, Fudan University in Shanghai, China

The study included 42,853 people with an average age of 48 who did not have Parkinson's disease at the start of the study. They were followed up to 26 years.

Participants had regular medical exams and completed health questionnaires. Researchers reviewed results to determine if they had early signs of Parkinson's disease, including rapid eye movement sleep behavior disorder, constipation, depressive symptoms, body pain, impaired color vision, excessive daytime sleepiness and reduced ability to smell.

Participants completed a food diary every two to four years, listing what they ate and how often.

Researchers looked at several types of ultra processed foods including sauces, spreads, or condiments; packaged sweets; snacks or desserts; artificially or sugar-sweetened beverages; animal-based products; yogurt or dairy-based desserts; and packaged savory snacks. One serving was equivalent to a single can of soda, one ounce of potato chips, one slice of packaged cake, a single hot dog or one tablespoon of ketchup.

Researchers calculated how many ultra processed foods participants ate on average per day.

They divided participants into five groups. The highest group ate 11 or more servings of ultra-processed food per day on average. The lowest group ate an average of fewer than three servings per day.

After adjusting for factors such as age, physical activity and smoking, researchers found that participants who ate 11 or more servings of ultra processed foods per day had a 2.5-fold higher likelihood of having three or more early signs of Parkinson's disease compared to those consuming fewer than three servings per day.

When looking at individual early signs of Parkinson's disease, researchers also found that eating more ultra processed foods was tied to an increased risk for nearly all symptoms except constipation.

"Choosing to eat fewer processed foods and more whole, nutritious foods could be a good strategy for maintaining brain health," said Gao. "More studies are needed to confirm our finding that eating less processed food may slow down the earliest signs of Parkinson's disease."

A limitation of the study was that the amount of ultra processed food consumed was self-reported, so participants may not have remembered accurately how much and what specific foods they ate.

The study was supported by the National Institute of Neurological Disorders and Stroke, the municipal public health system in Shanghai, China, the National Natural Science Foundation of China and the China Postdoctoral Science Foundation.