Selenium, including forms such as selenium picolinate, has a biologically plausible role in supporting fertility due to its involvement in antioxidant defense and the functioning of selenoproteins, which play important roles in reproductive health for both males and females. Scientific studies have shown that selenium deficiency can negatively impact sperm motility and morphology in men, and may influence ovarian function and embryo development in women. Several observational studies have found associations between adequate selenium status and improved semen quality parameters, as well as reduced risk of pregnancy complications such as miscarriage and preeclampsia.

However, most human research focuses on selenium status or supplementation in general, not specifically on selenium picolinate. Randomized controlled trials investigating selenium supplementation for male infertility have yielded mixed results, with some showing improvements in sperm motility and quality, especially when selenium is combined with other antioxidants, and others finding no significant effect. Evidence for selenium in female infertility is more limited and mostly indirect. It is important to note that excessive selenium intake can be harmful, and supplementation should be approached cautiously.

In summary, while there is a scientific rationale and some supportive evidence for selenium supplementation in infertility, the strength of the evidence is moderate at best (rating 2/5), and direct high-quality clinical trials, particularly with selenium picolinate, are lacking.