40% to 70% of Parkinson's patients are now taking Vitamin D
Claude AI - Oct 2026
Short answer: nobody has counted directly, but recent surveys suggest that roughly 40–70% of people with Parkinson's in Western countries take vitamin D. Applied to the roughly 1 million Americans with Parkinson's [Parkinson's Foundation], that is very roughly 400,000–700,000 people in the US. That figure is my extrapolation. It probably runs high, because the survey samples lean toward educated, health-engaged patients.
| Survey | Setting | n | Taking vitamin D | Didn't discuss with doctor | Ref |
|---|---|---|---|---|---|
| MVP study | US online cohort, 2021 | 1,084 | 71% | Not reported | [Mischley 2023] |
| DISH study | US survey | 205 | ≈62% (74% of supplement users) | 29% of supplement users | [South Med J] |
| Vilnius PD center | Lithuania, 2022 | 169 | ≈38% (60% of supplement users) | 53% of supplement users | [Guk 2025] |
| Denver clinics | US, 2012–13 | 207 | 66% "vitamins" (D not separated) | Not reported | [Finseth 2015] |
| NET-PD LS-1 | US early-PD cohort, older | 1,741 | ≈12% at ≥400 IU/day | Not reported | [NET-PD] |
| General US population ≥60 | NHANES 2017–18 | National | 36.9% | — | [NCHS 399] |
The ≈62% and ≈38% figures are my calculations from each paper's numbers: share of patients using any supplement × share of those users taking vitamin D.
Trend: Use appears to have risen a lot. In the older NET-PD cohort, about 5% took vitamin D alone, 7% took it with a multivitamin, 34% took a multivitamin alone, and 54% took no supplement. The authors judged that ≥400 IU/day was uncommon and similar to the general US population. By 2021, vitamin D was the most-used supplement in the MVP cohort, at 71%. The two cohorts differ, though. MVP recruited through social media and other channels, and 47% of its participants had graduate or professional degrees.
"Without the doctor's recommendation": I found no survey that asked who recommended vitamin D specifically. The nearest proxy is whether patients told their doctor about their supplements in general:
- In the US DISH survey, 29.2% of supplement users had not discussed their supplements with a healthcare practitioner [South Med J].
- In Lithuania, only 47.1% of supplement users discussed it with their neurologist or treating physician [Guk 2025].
So, somewhere between about a quarter and a half of these patients are self-directing without telling their doctor.
References
- [Mischley 2023 – MVP nutraceuticals]
- [DISH – Southern Medical Journal]
- [Guk 2025 – Lithuania]
- [Finseth 2015 – Colorado CAM]
- [NET-PD LS-1 vitamin D]
- [NCHS Data Brief 399]
- [Parkinson's Foundation statistics]
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A gut-friendly form of Vitamin D is strongly recommended