Objectives

Our systematic review and meta-analysis aimed to uncover the relationship between UPFs intake and neurodegenerative disorders, including multiple sclerosis (MS), Parkinson's disease (PD), Alzheimer's disease (AD), cognitive impairment, and dementia.

Setting

A systematic search was conducted using the Scopus, PubMed/MEDLINE, and ISI Web of Science databases without any limitation until June 24, 2023. Relative risk (RR) and 95% confidence interval (CI) were pooled by using a random-effects model, while validated methods examined quality and publication bias via Newcastle-Ottawa Scale, Egger's regression asymmetry, and Begg's rank correlation tests, respectively.

Results

Analysis from 28 studies indicated that a higher UPFs intake was significantly related to an enhanced risk of MS (RR = 1.15; 95% CI: 1.00, 1.33; I²= 37.5%; p = 0.050; n = 14), PD (RR = 1.56; 95% CI: 1.21, 2.02; I²= 64.1%; p = 0.001; n = 15), and cognitive impairment (RR = 1.17; 95% CI: 1.06, 1.30; I²= 74.1%; p = 0.003; n = 17), although not AD or dementia. We observed that a 25 g increment in UPFs intake was related to a 4% higher risk of MS (RR = 1.04; 95% CI: 1.01, 1.06; I²= 0.0%; p = 0.013; n = 7), but not PD. The non-linear dose-response relationship indicated a positive non-linear association between UPF intake and the risk of MS (P_nonlinearity = 0.031, P_{dose-response}= 0.002). This association was not observed for the risk of PD (P_nonlinearity = 0.431, P_{dose-response}= 0.231).

Conclusion

These findings indicate that persistent overconsumption of UPFs may have an adverse impact on neurodegenerative conditions, potentially leading to a decline in quality of life and reduced independence as individuals age.