Eating habits tied to Parkinson’s risk: sweets and processed meats raise odds, fruit lowers them

By Vijay Kumar MalesuReviewed by Susha Cheriyedath, M.Sc.Oct 29 2025

An Italian study shows that everyday dietary patterns, not just genetics or toxins, may influence Parkinson’s disease risk, highlighting the protective power of fruit and the potential harm of sweets and processed meats.

Study: The impact of diet on Parkinson's disease risk: A data-driven analysis in a large Italian case-control population. Image Credit: Kotcha K / Shutterstock

In a recent study published in the Journal of Parkinson’s Disease, researchers evaluated data-driven dietary patterns and compared their contributions with non-dietary factors in relation to PD risk.

Gut-Brain Connection and Dietary Influence on PD

What if grocery basket choices nudge the brain toward or away from PD? PD is a neurodegenerative movement disorder that burdens households with mobility limits, sleep problems, and care expenses. The gut-brain connection suggests that diet could influence oxidative stress and inflammation, which damage dopaminergic neurons. Yet studies of single foods conflict across populations, and predefined patterns such as the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) do not pinpoint specific culprits or protectors.

Need for Data-Driven Analysis of Eating Patterns

A data-driven lens that lets foods cluster may reveal clear signals. However, causality remains uncertain, and recall and selection biases are possible in retrospective studies. Further research is needed to identify actionable levers.

Study Design and Participant Selection

This retrospective case-control study was conducted in six Italian neurology centers between September 2018 and September 2019. Senior movement-disorder neurologists diagnosed idiopathic PD using published criteria, while monogenic PD and atypical Parkinsonism were excluded. Healthy controls were relatives of non-PD outpatients and were frequency-matched to cases by five-year age band, sex, and center.

Dietary Assessment Using the Italian Food-Frequency Questionnaire

Diet was assessed with a validated 77-item Food-Frequency Questionnaire (FFQ) tailored to Italian eating habits, with seasonal items queried in their primary season. Participants reported intake for the period preceding motor-symptom onset in cases and the matched calendar period in controls.

Collection of Non-Dietary Lifestyle and Exposure Variables

Non-dietary variables were collected with a semi-structured instrument, including coffee consumption, smoking, physical activity converted to Metabolic Equivalents of Task (METs), family history of PD, dyspepsia, occupational exposure to pesticides, petroleum oils, and metals, and exposure to general anesthesia.

Statistical Analysis of Diet and PD Associations

To reduce dimensionality, dietary variables entered Principal Component Analysis (PCA) followed by Exploratory Factor Analysis (EFA) with varimax rotation, factors with eigenvalues greater than 1.0 were retained and loadings less than 0.30 were excluded. Associations with PD were tested using non-conditional logistic regression adjusted for age, sex, education, and center, then compared with non-dietary factors in the same model. Spearman correlation analyses examined relationships with age and disease duration. Two-tailed tests with p < 0.05 were considered statistically significant.

Participant Characteristics and Identified Food Patterns

In total, 1,292 people completed the study, including 680 with PD and 612 matched controls. Sex distribution and body mass index were similar, but cases were slightly older and had fewer years of education. Factor analysis of 77 food items yielded seven patterns: sweets, fruits, red meat, salads, cruciferous vegetables with peas and beans, cured meats, and alcoholic beverages. Together, these seven factors explained about 48% of the total variance in dietary intake.

Dietary Patterns Linked to Higher or Lower PD Odds

In unadjusted comparisons, sweets, red meat, and cured meats were more frequent in cases. Factor 5 (cruciferous vegetables, peas, beans) was also higher in cases in unadjusted analyses but did not persist in multivariable models. In the multivariable model that included diet and non-diet variables, four factors remained independently associated with PD. Each step up in frequency was linked to higher odds for sweets (odds ratio [OR] 1.20, 95% confidence interval [CI]: 1.09–1.32, p < 0.0001), red meat (OR 1.15, 95% CI: 1.03–1.27, p = 0.01), and cured meats (OR 1.32, 95% CI: 1.13–1.54, p < 0.0001). Fruit was protective (OR 0.84, 95% CI: 0.74–0.95, p = 0.008), with citrus items driving most of the association.

Stronger Influence of Non-Dietary Risk Factors

Non-dietary factors showed larger risk elevations than dietary ones: family history (OR 3.02), dyspepsia (OR 1.56), exposure to pesticides (OR 2.08), petroleum oils (OR 4.99), metals (OR 3.52), and general anesthesia (OR 7.69). Coffee consumption (OR 0.58) and ever-smoking (OR 0.69) were protective.

Physical Activity Confounding and Correlation Insights

Physical activity was excluded from the final model because it was confounded by dietary patterns rich in sweets, red meat, and processed meats. This finding suggests that the apparent benefits of higher physical activity observed in prior studies may partly reflect correlated dietary habits. Correlation tests in cases showed no relationship between disease duration and fruit, red meat, or cured meats, but a small positive correlation for sweets (Spearman r = 0.10, p = 0.03), suggesting possible reverse causation, such as increased sweet intake after diagnosis due to changes in taste or reward pathways, or age-related shifts.

Age-Related Dietary Correlations in Cases and Controls

In cases, age correlated negatively with sweets and cured meats. In controls, age correlated positively with sweets and negatively with cured meats, indicating that the latter associations were relatively stable across age. The authors noted that vegetables and alcohol factors were not independently associated with PD in adjusted analyses.

Comparative Magnitude of Dietary and Environmental Effects

Overall, data-driven patterns rich in sweets, red meat, and cured meats were associated with higher odds of PD, whereas a fruit-forward pattern was associated with lower odds. When modeled together, the adverse dietary patterns showed smaller effect sizes than established non-dietary exposures and family history, while the protective effect of fruit was comparable in magnitude to coffee and smoking. The strong association observed for general anesthesia may reflect anesthesia-related mechanisms or surgeries undertaken for prodromal conditions that precede PD diagnosis.

Practical Implications for PD Prevention

These results point to practical, relatable levers, limiting sweets and processed or red meats, and emphasizing fruit, especially citrus, may complement proven strategies that target environmental exposures and other lifestyle factors.

Conclusions and Future Research Directions

In this Italian case-control sample, a data-driven approach linked three eating patterns, sweets, red meat, and cured meats, to higher odds of PD, and one pattern with fruit, especially citrus, to lower odds. When analyzed alongside well-known non-diet contributors, dietary risk factors were smaller in magnitude, whereas the protective effect of fruit resembled that of coffee and smoking.

Given the retrospective case-control design and single-time FFQ, these associations should not be interpreted as causal. Dietary patterns are specific to Italy and may not generalize to non-Mediterranean populations.

Because families can change what is on the plate more readily than genetics or past exposures, emphasizing fruit and dialing down sweets and processed meats is a practical step. Prospective cohorts and trials are needed to verify causality and quantify impact, and future work should test whether these relationships hold in more diverse populations.