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. 2025 Jun 9;12:1500875. doi: 10.3389/fnut.2025.1500875

Table 1.

Main characteristics of eligible studies for the analysis of vitamin D supplementation in Parkinson’s disease.

Studies, country Number Age [year; mean (SD)] Sex male (%) Treatment Adherence Study duration (m) 25(OH)D serum concentration changes at baseline and endpoints [ng/mL; mean (SD)]
T C T C T C T C T C
Sato et al. (35)
Japan
43 43 70.5 (2.9) 70.7 (3.3) 18 (41.9) 17 (39.5) 1 μg 1α (OH)D3/d Placebo 93% 18 11.0 (5.9) 11.8 (6.9)
11.3 (4.3) 11.6 (6.4)
Dubose et al. (33)
USA
16 14 64 (7.9) 65 (7.3) 11 (68.8) 8 (57.1) Vit. D3 50,000 IU/w + Vit. D 600 IU/d Placebo+Vit. D 600 IU/d 90% 0 20.2 (8.6) 24.9 (8.6)
3 69.1 (41.7) 25.9 (9.1)
6 71.9 (38.3) 25.5 (7.5)
Suzuki et al. (23)
Japan
56 58 72.(6.6) 71.2 (6.9) 31 (52) 29 (53) Vit. D3 1,200 IU/d Placebo 91% 12 22.5 (9.7) 21.1 (8.8)
41.7 (12.6) 21.4 (9.8)
Habibi et al. (34)
Iran
60 60 44.02 (13.2) 49.9 (11.4) na na Vit. D3 1,000 IU/d Placebo na 3 na na
Hiller et al. (4)
USA
28 30 64.63 (8.1) 68.75 (7.6) 23 (82.1) 20 (66.7) Vit. D 10,000 IU/d + 1,000 mg Calcium/d Placebo+1,000 mg Calcium/d 88% 4 30.33 (5.378) 29.92 (6.324)
61.1 (na) 27.8 (na)
Barichella et al. (30)
Italy
75 75 66.8 (8.2) 68.5 (7.9) 50 (66.6) 46 (61.3) Vit. D 1,600 IU/d + 1,000 mg Calcium/d + 40 g of whey proteins+hospital diet Hospital diet 91% 1 6.6 (14.1)
changes
−3.2(−13)
changes
Bytowska et al.(32) Poland 21 21 63 (9) 66 (6) 6 13 Vit. D3 4,000–6,000 IU/d Placebo 69% 3 25.55 (8.94) 21.98 (10.91)
34.99 (12.27) <21.98(na)
Zali et al. (36)
Iran
23 23 56.34 (10.23) 55.73 (10.98) 14 (60.9) 15 (65.2) Probiotics + 400 IU Vit. D Placebo 100% 4 na na

T, treatment group; C, control group; 25 (OH) D, 25-hydroxyvitamin D; na, not available; Vit. D, vitamin D.