Table 3.

The characteristics of the multiple sclerosis (MS) patients assessed within the studies included in the systematic review.

Ref.	Number of Participants (Number of Females)	Age (Mean Years with SD)	Inclusion Criteria/Exclusion Criteria
[35]	94 (80)	31.4 ± 7.6 for vitamin D supplementation group 34.6 ± 10.1 for placebo group	Inclusion: aged 18–55 years; definite diagnosis of relapsing remitting multiple sclerosis according to McDonald criteria; EDSS score <4; no relapse 30 days before inclusion; negative β-HCG test for women in child-bearing age Exclusion: pregnancy; lactation; any disease other than MS; 25(OH)D serum level >85 ng/mL; past history of renal or hepatic disease; relapse during the study; received corticosteroids in the previous 30 days; calcium >11 mg/dL; aspartate transaminase or alanine transaminase >3 times normal values; alkaline phosphatase >2.5 times normal values
[36]	40 (26)	38.5 ± 7.8 for vitamin D supplementation group 37.6 ± 9.6 for placebo group	Inclusion: aged 18–55 years; diagnosed with relapsing remitting multiple sclerosis according to the original or 2005 revised McDonald criteria confirmed by MRI; treated with interferon-β1α; first clinical event in the previous 5 years; active disease in the previous 18 months, but not in the 30 days prior to inclusion Exclusion: use of oral or systemic glucocorticoids or ACTH within 30 days prior to inclusion; a history or presence of severe depression; a history of suicide attempt or current suicidal ideation; current or past drug or alcohol abuse; missing data
[37]	35 (19)	27.0 ± 4.0	Inclusion: aged ≥18 years; relapsing remitting multiple sclerosis according to McDonald criteria; no exacerbations; no gadolinium enhancing lesions on MRI; no corticosteroid therapy within four weeks prior to recruitment; regular treatment with interferon-β Exclusion: treatment other than interferon; high-dose of vitamin D (daily intake of at least 25 µg) before inclusion to the study; immunomodulatory therapy changed within the past 3 months; history of systemic glucocorticoid therapy or relapse within 30 days; severe depression; pregnancy; serum creatinine >1.5 mg/dL; hypersensitivity to vitamin D preparations; history of hyperparathyroidism, tuberculosis, sarcoidosis, or nephrolithiasis
[38]	149 (107)	37.52 ± 9.82	Inclusion: diagnosed with multiple sclerosis according to 2010 revised McDonald criteria Exclusion: disorders related to vitamin D deficiency (e.g., parathyroid pathologies); other acute or chronic disease at time of blood sampling determined by routine tests; receiving vitamins (vitamin D or multivitamin compounds) as supplements in the 6 months preceding data collection; relapse in the last 30 days; pregnancy; breastfeeding; other neurological or immune-mediated disease; skin diseases; medication use with a medical recommendation to avoid exposure to the sun; applying hydrochlorothiazide, barbiturates, phenytoin or digitalis
[39]	1401 (1150)	48.4 ± 10.5	Inclusion: aged ≥18 years, diagnosed with multiple sclerosis (MS) by a medical doctor Exclusion: missing data *
[40]	1401 (1152)	48.4 ± 10.5	Inclusion: aged ≥18 years, diagnosed with multiple sclerosis (MS) by a medical doctor Exclusion: missing data *

* Data provided on request; ACTH—adrenocorticotropic hormone; β-HCG—beta subunit of human chorionic gonadotropin; EDSS—expanded disability status scale; MRI—magnetic resonance imaging.