An umbrella review of systematic reviews with meta-analysis on the role of vitamins in Parkinson's disease

Dietary vitamin E intake and risk of Parkinson's disease: a cross-sectional study

Objective

Current evidence on the association between dietary vitamin E intake and the risk of Parkinson's disease (PD) is limited. The aim of the study was to explore the association of dietary vitamin E intake with PD in the United States among adults over 40 years.

Methods

We conducted a cross-sectional study with data collected from National Health and Nutrition Examination Survey (NHANES) from 2009 to 2018. A total of the sample of 13,340 participants were included. To identify the different characteristics of the participants, we utilized propensity score matching (PSM) to reduce the effects of selection bias and confounding variables. Weighted univariate and multivariable logistic regression were used to examine the association between dietary vitamin E intake and PD before and after matching. Then, restricted cubic spline (RCS) was used to visually describe the possible non-linear relationships. Finally, we employed the subgroup analysis to further investigate the relationship between dietary vitamin E intake and PD.

Results

According to the weighted univariate and multivariable logistic regression analysis, vitamin E intake was inversely associated with the risk of PD before and after matching. The results of RCS analysis revealed no non-linear inverse relationship between vitamin E intake and PD before and after matching. The subgroup analysis showed that age may influence the negative association between vitamin E and PD (P < 0.05 for interaction).

Conclusion

Among participants over 40 years of age, vitamin E intake was negatively associated with the risk of PD. Our data may support the supplementation of vitamin E to be used as an intervention strategy for the occurrence of PD.

Association between the risk and severity of Parkinson's disease and plasma homocysteine, vitamin B12 and folate levels: a systematic review and meta-analysis

Background

Parkinson's disease (PD) is recognized as the second most prevalent progressive neurodegenerative disease among the elderly. However, the relationship between PD and plasma homocysteine (Hcy), vitamin B12, and folate has yielded inconsistent results in previous studies. Hence, in order to address this ambiguity, we conducted a meta-analysis to summarize the existing evidence.

Methods

Suitable studies published prior to May 2023 were identified by searching PubMed, EMBASE, Medline, Ovid, and Web of Science. The methodological quality of eligible studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). Meta-analysis and publication bias were then performed using R version 4.3.1.

Results

The results of our meta-analysis, consisting of case-control and cross-sectional studies, showed that PD patients had lower folate and vitamin B12 levels (SMD [95%CI]: -0.30[-0.39, -0.22], p < 0.001 for Vitamin B12; SMD [95%CI]: -0.20 [-0.28, -0.13], p < 0.001 for folate), but a significant higher Hcy level (SMD [95%CI]: 0.86 [0.59, 1.14], p < 0.001) than healthy people. Meanwhile, PD was significantly related to hyperhomocysteinemia (SMD [95%]: 2.02 [1.26, 2.78], p < 0.001) rather than plasma Hcy below 15 μmol/L (SMD [95%]: -0.31 [-0.62, 0.00], p = 0.05). Subgroup analysis revealed associations between the Hcy level of PD patients and region (p = 0.03), age (p = 0.03), levodopa therapy (p = 0.03), Hoehn and Yahr stage (p < 0.001), and cognitive impairment (p < 0.001). However, gender (p = 0.38) and sample size (p = 0.49) were not associated.

Conclusion

Hcy, vitamin B12, and folic acid potentially predict the onset and development of PD. Additionally, multiple factors were linked to Hcy levels in PD patients. Further studies are needed to comprehend their roles in PD.

Vitamin D deficiency and genetic polymorphisms of vitamin D-associated genes in Parkinson's disease

Parkinson's disease (PD) and vitamin D share a unique link as vitamin D deficiency (VDD) prevails in PD. Thus, an in-depth understanding of vitamin D biology in PD might be crucial for therapeutic strategies emphasising vitamin D. Specifically, explicating the effect of VDD and genetic polymorphisms of vitamin D-associated genes in PD, like VDR (vitamin D receptor) or GC (vitamin D binding protein) may aid the process along with polymorphisms of vitamin D metabolising genes (e.g., CYP2R1 and CYP27A1) in PD. Literature review of single nucleotide polymorphisms (SNPs) related to vitamin D levels [GC (GC1-rs7041 and GC2-rs4588), CYP2R1, CYP24A1 and CYP27B1] and vitamin D function [VDR (FokI - rs2228570 and rs10735810; ApaI - rs7976091, rs7975232BsmI and rs1544410; and TaqI - rs731236)] was conducted to explore their relationship with PD severity globally. VDR-FokI polymorphism was reported to be significantly associated with PD in Hungarian, Chinese and Japanese populations, whereas VDR-ApaI polymorphism was found to affect PD in the Iranian population. However, VDR-TaqI and BsmI polymorphisms had no significant association with PD severity. Conversely, GC1 polymorphisms reportedly affected vitamin D levels without influencing the disease severity. CYP2R1 (excluding rs1993116) was also reportedly linked to clinical manifestations of PD. Genetic polymorphisms might cause VDD despite enough sunlight exposure and vitamin D-rich food intake, enhancing inflammation, there by influencing PD pathophysiology. Knowledge of the polymorphisms associated with VDD appears promising for developing precision vitamin D-dosing therapeutic strategies against PD.