Summary: A large, long-term study finds a strong association between high consumption of ultra-processed foods and early, prodromal signs of Parkinson’s disease. Tracking 42,853 adults for up to 26 years, researchers observed that individuals who averaged 11 or more servings of ultra-processed food per day were about 2.5 times more likely to exhibit multiple early Parkinson’s symptoms than those who ate fewer than three servings daily.
The early indicators identified in the study included sleep disturbances, a diminished sense of smell, depressive symptoms, and body pain; constipation did not show a clear link. While the research does not establish cause and effect, it adds to growing evidence that dietary patterns—particularly heavy reliance on ultra-processed foods—may influence brain health and the earliest stages of neurodegenerative disease.
Key Facts:
- Elevated likelihood: Eating 11+ servings of ultra-processed food daily was associated with a 2.5-fold higher chance of having three or more prodromal Parkinson’s symptoms.
- Prodromal symptoms assessed: Rapid eye movement sleep behavior disorder, impaired smell, depressive symptoms, excessive daytime sleepiness, impaired color vision and body pain were among the signs examined.
- Dietary implication: Results support limiting ultra-processed foods and prioritizing whole, nutrient-dense foods to support long-term brain health.
Source: AAN
Overview of the research
Published online May 7, 2025, in Neurology, the study investigated links between ultra-processed food consumption and prodromal Parkinson’s disease — the earliest stage of the illness when underlying neurodegeneration may begin but classic motor symptoms such as tremor, slowness and balance problems have not yet emerged. These prodromal signs can appear years or even decades before a formal Parkinson’s diagnosis.
Lead author Xiang Gao, MD, PhD, of the Institute of Nutrition at Fudan University in Shanghai, emphasized the importance of dietary choices for long-term brain health. The investigators note that while the findings show an association rather than proof of causality, the pattern aligns with mounting research that diet can influence neurological aging and disease risk.
The cohort included 42,853 participants with an average baseline age of 48 who had no Parkinson’s diagnosis at enrollment. Participants completed periodic health questionnaires and medical exams over follow-up periods of up to 26 years. Researchers specifically evaluated standard prodromal markers: rapid eye movement sleep behavior disorder (RBD), constipation, depressive symptoms, body pain, impaired color vision, excessive daytime sleepiness and reduced sense of smell.
Dietary intake was tracked via food diaries collected every two to four years. Investigators categorized multiple types of ultra-processed foods — including packaged sweets, snacks and desserts, sugar-sweetened beverages, processed animal products such as hot dogs, yogurt- or dairy-based desserts, sauces and packaged savory items. For consistency, one serving was defined as a single can of soda, an ounce of chips, one slice of packaged cake, one hot dog, or one tablespoon of ketchup, among other equivalents.
Participants were assigned to quintiles based on daily average servings of ultra-processed foods. The highest-intake group averaged 11 or more servings per day, while the lowest averaged fewer than three servings. After adjusting for demographic and lifestyle factors including age, physical activity and smoking, the highest-intake group showed a 2.5-fold greater likelihood of having three or more prodromal Parkinson’s symptoms compared with the lowest-intake group. Nearly all individual prodromal signs were more likely with higher processed-food intake, with the exception of constipation.
The authors recommend that choosing whole, minimally processed foods over ultra-processed alternatives may be a sensible strategy to support brain health. They also call for further research to confirm whether reducing ultra-processed food intake can slow or modify the emergence of early Parkinson’s signs.
A key limitation of the study is reliance on self-reported dietary data, which may be affected by recall bias or misclassification of food types and portion sizes. Despite this limitation, the large sample size and long follow-up strengthen the observed associations.
Funding: The research received support from the National Institute of Neurological Disorders and Stroke, Shanghai’s municipal public health system, the National Natural Science Foundation of China and the China Postdoctoral Science Foundation.
About this diet and Parkinson’s disease research news
Author: Renee Tessman
Source: AAN
Contact: Renee Tessman – AAN
Image: Image credit to Neuroscience News
Original Research: Findings will appear in Neurology