Vitamin D can also regulate FOXP3 expression in T cells, thus inducing the differentiation of this cells to FOXP3+ T regulatory cells (T reg), which have an immunosuppressor activity [105,106], and can promote the secretion of anti-inflammatory IL-10 from T cells [107]. It was also reported in a placebo-controlled trial on healthy adults that high dose vitamin D supplementation significantly increased the frequency of circulating Tregs [108].