And as it turns out, healthy vitamin D levels are pretty critical for optimal sexual function and desire. In a 2018 study published by the International Journal of Impotence Research, the same researchers found similar results in men: Participants with healthy vitamin D levels were found to have better scores in erectile function1, orgasmic function, and sexual desire than men with vitamin D deficiency or insufficiency. Translation? Maintaining truly optimal levels of vitamin D can help support a healthy libido—even in the winter! Daily vitamin D supplementation, specifically, has been found to improve testosterone levels2 in men and result in healthier levels of estrogen and progesterone3 in menstruating women. Considering testosterone, estrogen, and progesterone all play a role in sexual desire and arousal, it may be time to consider a high-quality vitamin D supplement if your sex drive is hurting this winter (read mbg’s guide to finding the best vitamin D supplement here).