A recent study published by the journal Neural Transmission found that low vitamin D status is linked with endothelial dysfunction in newly diagnosed Parkinson’s patients.
Parkinson’s disease (PD) is a neurodegenerative disorder which affects the nervous system, resulting in symptoms such as tremors, slow movement, muscle rigidity and difficulty walking.
Many individuals with PD also experience endothelial dysfunction, which is characterized by a lack of balance between dilation and constriction of the blood vessels. This may occur as a result of the individual’s compromised autonomic system or as a side effect from their anti-Parkinson’s medication. Evidence supports that endothelial dysfunction may play a role in the pathogenesis and progression of neurodegenerative diseases, including PD.
Research has shown that a relationship exists between low vitamin D levels and endothelial dysfunction. Since vitamin D receptors are found on human endothelial cells, researchers hypothesize that vitamin D may act locally to mediate the effects on the vascular system, providing a possible mechanism for this relationship.
Despite the high prevalence of endothelial dysfunction in PD patients and the established relationship between vitamin D and endothelial function, no studies have evaluated the relationship of all three variables.
In the current case-control study, researchers wanted to determine if vitamin D status is related to endothelial dysfunction in newly diagnosed PD patients. A total of 81 patients with early PD and 52 healthy controls were enrolled in the study. Diagnosis of PD was determined according to the UK Brain Bank Criteria, which is a standard tool used to diagnose PD.
All participants had their serum 25(OH)D levels measured and flow-mediated dilation (FMD) assessed. FMD is a commonly used clinical marker to determine endothelial function. Lower FMD results indicate decreased endothelial function.
Did the researchers find a relationship between vitamin D and endothelial function in Parkinson’s patients? Here is what they found:
- The mean 25(OH)D status in all participants was 23.6 ng/ml.
- At baseline, PD patients had significantly lower 25(OH)D levels compared to controls (21.8 ± 9.5 vs. 25.2 ± 9.3 ng/ mL; p < 0.05).
- 54.8% of PD patients were vitamin D deficient (≤ 20 ng/ml; 50 nmol/l) compared to only 37.2% of healthy controls (p < 0.05).
- FMD was significantly lower in PD patients when compared with controls (1 ± 1.8% vs. 8.1 ± 2.1%; p = 0.02).
- In PD patients, FMD was lower in vitamin D deficient than the vitamin D insufficient (20 – 30 ng/ml; 50 – 75 nmol/l) individuals (6.7 ± 1.8% 7.4 ± 1.1%; p = 0.04). This was also the case when comparing vitamin D deficient and vitamin D sufficient (≥30 ng/ml; 75 nmol/l) PD patients (6.7 ± 1.8% vs. 9.0 ± 1.8%; p < 0.05).
- Vitamin D levels were positively associated with FMD (r = 0.471; p < 0.001). This relationship remained significant after adjusting for age, which is negatively associated with vitamin D status (r = -0.347; p = 0.002).
The researchers summarized their findings,
“Our study demonstrates that FMD, a measure of endothelial function, was positively related to serum vitamin D status in patients with early PD.”
“In conclusion, our study demonstrates that vitamin D deficiency is common and is associated with endothelial function, independent of traditional cardiovascular risk factors in PD. Vitamin D supplementation is simple cheap, and may reverse endothelial dysfunction.”
It is important to note, that due to this study’s design, the findings were able to confirm association only, not causation. The researchers call for prospective, large-scale, randomized controlled trials to determine if vitamin D supplementation may improve endothelial function in vitamin D deficient PD patients.
Sturges, M. & Cannell, JJ. Study finds low vitamin D status is linked with endothelial dysfunction in newly diagnosed Parkinson’s patients. The Vitamin D Council Blog/Newsletter, September 23, 2015.