The participants took either a vitamin supplement or a placebo for 8 to 12 weeks.

The results were as follows:

Vitamin B6 (40 mg/day) improved RLS symptoms and sleep quality in the participants with primary RLS (i.e., RLS without a known medical cause).
Vitamin C (250 mg/day) was as effective as pramipexole (a common and effective medication to treat RLS).^[1]
Vitamin E (400 IU/day) also improved symptoms in hemodialysis-associated RLS, both alone and combined with vitamin C.
Vitamin D (50,000 IU per week) did not improve RLS symptoms.

Common side effects of vitamin supplementation included nausea, indigestion, and abdominal pain.

Can vitamin supplements help with restless leg syndrome? Original paper