Table 1 Formulated question of the study based on PICOS

P(Participants)

Endometriosis patient

I(Intervention)

Vitamin C/E/D with no limits on the dose,frequency and so on

C(Comparisons)

No supplementation or placebo

O(Outcomes)

Primary:chronic pelvic pain,dysmenorrhea,dyspareunia;

Secondary outcome: oxidative stress markers,fertility

S(Study type)

Randomized controlled trials(RCTs)