medwireNews: The long-term consumption of ultra-processed food (UPF) is associated with an increased risk for developing nonmotor prodromal Parkinson disease (PD) features, suggests a study published in Neurology.
Peilu Wang (Fudan University, Shanghai, China) and colleagues say the association was “robust” and the findings “call for interventional studies to investigate whether reducing UPF consumption may slow PD progression during and before the prodromal phase.”
The study investigators conducted a longitudinal analysis of data from repeated food frequency questionnaires carried out every 2 to 4 years between 1984 and 2006 in 42,853 participants without a history of PD (mean age 47.8 years, 58.6% women). The individuals were participants from two cohorts in the USA, namely the Nurses’ Health Study (NHS, n=25,095) and the Health Professionals Follow-Up Study (HPFS, n=17,758).
Food items were categorized into four groups according to the NOVA classification system: unprocessed or minimally processed foods, processed culinary ingredients, processed foods, and UPF. UPF includes foodstuffs that have undergone extensive processing, often including added ingredients like artificial sweeteners, colorings, and preservatives, and contain few or no whole foods.
After a 6-year lag to remove potential reverse causation, the team then assessed the incidence of two prodromal PD features in both cohorts in 2012; probable rapid eye movement (REM) sleep behavior disorder (pRBD; Mayo Sleep Questionnaire) and constipation (bowel movement every other day or less frequently or taking laxatives at least twice a week).
And the incidence of an additional five nonmotor prodromal symptoms – hyposmia (Brief Smell Identification Test), impaired color vision (Roth Color Test), excessive daytime sleepiness (Epworth Sleepiness Scale), body pain, and depressive symptoms (both using the Short-Form Health Survey) – was assessed between 2014 and 2015 in a subset of approximately 23% of patients who did not have pRBD or constipation in 2012.
The investigators report that 16.8% of people in the NHS cohort and 17.2% of those in the NPFS cohort developed three or more of the seven prodromal PD features.
Across the two cohorts, participants in the highest quintile for average cumulative UPF consumption (10.9–11.5 servings per day) had a significant 2.47 times higher likelihood of having three or more features when compared with those in the lowest quintile (2.7–2.8 servings per day), after adjusting for age, BMI, physical activity, smoking, caffeine, alcohol, and energy intake, and diet quality. The odds ratios (ORs) for the two cohorts separately were 2.23 and 2.93, respectively.
The study also showed that the association between high UPF intake and an increased risk for three or more prodromal features was consistent and significant when assessed at different timepoints during the study, with ORs of 1.50 in 1986, 1.83 in 1990, 1.87 in 1994, 2.04 in 1998, 1.72 in 2002, and 2.54 in 2006.
The investigators note that there was “a slightly stronger association for recent and long-term [UPF] consumption.”
The pooled, adjusted ORs for having two or more, and one or more, prodromal PD features in the highest versus lowest UPF consumption quintiles were 1.58 and 1.57, respectively.
The association between high UPF intake and prodromal PD features was robust across different combinations of features, say Wang and colleagues. When they removed constipation as a measurable feature from the analysis (to control for the likely low fiber diet of high UPF consumers), individuals with a high UPF intake had a significant OR of 2.00 for developing three or more prodromal features compared with individuals with a low UPF intake.
There was also a significant OR of 2.47 for the specific combination of constipation, pRBD, and hyposmia in high versus low UPF consumers, and high UPF consumers had increased ORs for individual prodromal features, namely pRBD (OR=1.21), constipation (OR=1.62), body pain (OR=1.70), and depressive symptoms (OR=1.52).
The individual UPF groups most associated with prodromal PD features were sauces, spreads or condiments; packaged sweet snacks or desserts; artificially or sugar-sweetened beverages; animal-based products; yogurt or dairy-based desserts; and packaged savory snacks.
In an associated editorial, Maria Maraki and Nikolaos Scarmeas, both from National and Kapodistrian University of Athens in Greece, say that the study “stands out not only for its power but also for its methodological rigor.”
They believe it “reinforces a crucial message: excessive UPF consumption not only is a risk factor for metabolic diseases but may also accelerate neurodegenerative processes and associated symptoms and conclude that “[m]inimizing UPFs and prioritizing whole, nutrient-dense foods could be a vital strategy for reducing PD risk.”
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Neurology 2025; doi:10.1212/WNL.0000000000213562
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