Vitamin D and enzymes metabolising its receptors are found in the ovaries and endometrium of women with and without endometriosis (Buggio et al., 2016; Colonese et al., 2015) .1,25-dihydroxy vitamin D (Vitamin D3) has immune-modulating effects on cell differentiation and proliferation in normal and malignant cell types, which increase anti-inflammatory cytokines (IL-4 and transforming growth factor beta-1) and decrease pro-inflammatory cytokines (TNF-α, IL-2, and IL-6), suggesting that vitamin D may help to improve chronic inflammatory diseases (Lagana et al., 2017, Sassi et al., 2018). Here, IL2 is linked to endometriosis.