Ultraprocessed food linked to early signs of Parkinson's disease, study says

CNN

07-05-2025

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Eating about a dozen servings of ultraprocessed food each day could more than double your risk of developing Parkinson's disease, according to a new study.
A single serving in the study was 8 ounces of diet or sugar-sweetened soda, a single hot dog, one slice of packaged cake, a mere tablespoon of ketchup or 1 ounce of potato chips — a typical small bag of chips is 1.5 ounces.
'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,' said senior study author Dr. Xiang Gao, a distinguished professor and dean of the Institute of Nutrition at Fudan University in Shanghai, China, in a statement.
This latest study is part of the 'growing evidence that diet might influence the development of Parkinson's disease,' Gao said.
While the study found that people who ate more ultraprocessed foods tended to report more early symptoms, it did not find a direct increase in the risk of Parkinson's disease itself, said Dr. Daniel van Wamelen, a clinical senior lecturer in neuroscience at King's College London. He was not involved in the new research.
'The study did not track whether participants were diagnosed with Parkinson's later on,' van Wamelen said in a statement. 'That said, having more of these symptoms suggests a higher risk over time.'
The study analyzed years of health and diet data on nearly 43,000 participants of the Nurses' Health Study and Health Professionals Follow-Up Study, two studies in the United States that have been gathering information on health behaviors for decades. The average age of people in the study was 48, and none had Parkinson's disease at the beginning of the study. All self-reported what they ate every few years — a limitation of the new research as participants may not have remembered their food intake accurately.
Ultraprocessed foods measured by the study included artificially or sugar-sweetened beverages; condiments, sauces and spreads; packaged sweets snacks or desserts; yogurt or dairy-based desserts; breads and cereals; and packaged savory snacks.
The study found a link between early signs of Parkinson's disease and all types of ultraprocessed foods except breads and cereals — a finding that indicates an underlying feature among most classes of ultraprocessed foods that may explain the results, the study said.
One reason could be ultraprocessed foods typically have less dietary fiber, protein and micronutrients — but do have added sugar, salt, and saturated or trans fats, the study said. Ultraprocessed foods also may impact the balance of flora in the gut, while additives may increase inflammation, free radicals and neuron death, the study said.
'With a sample size exceeding 42,800 participants and a long follow-up period up to 26 years, this study stands out not only for its power but also for its methodological rigor,' wrote the authors of a corresponding editorial published with the study.
The editorial was coauthored by Dr. Nikolaos Scarmeas, an associate professor of clinical neurology at Columbia University in New York City, and dietitian Maria Maraki, an assistant professor of sports medicine and exercise biology at the National and Kapodistrian University of Athens, Greece. Neither were involved in the new research.
'The prevention of neurodegenerative diseases may begin at the dinner table,' they wrote. 'Excessive UPF consumption not only is a risk factor for metabolic diseases but may also accelerate neurodegenerative processes and associated symptoms.'
In the new study, published Wednesday in the journal Neurology, researchers looked at the prodromal stage of Parkinson's disease — early signals that appear years to decades before the tremors, stiff muscles, slow gait and changes in posture that are hallmark symptoms of Parkinson's.
Body pain, constipation, signs of depression, changes in the ability to smell or see colors, and excessive daytime sleepiness can all be early signs of Parkinson's disease, according to the Parkinson's Foundation.
An extremely unusual sleep disorder, in which people can move during REM, or the rapid eye movement stage of sleep, is also a key early sign, according to research. The body is typically paralyzed during REM sleep so it cannot get up and act out any dreams.
The study found that people who ate about 11 servings a day of ultraprocessed food — compared to people who only ate three — had a 2.5-fold greater likelihood of exhibiting three or more of the early signs of Parkinson's.
In addition, eating more ultraprocessed foods was tied to an increased risk for nearly all symptoms except constipation, according to the study. This finding held true even after researchers accounted for other factors, such as age, physical activity and smoking, that might impact the results.
'Parkinson's is an incurable disease,' Gao said in an email. 'In our previous study based on the same populations used for the current analysis, we found that a healthy dietary pattern and physical activity could slow the disease progression.
'Choosing to eat fewer processed foods and more whole, nutritious foods could be a good strategy for maintaining brain health.'
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