Which mineral is involved in reproduction, thyroid function, and has an RDA of 55 mcg/day for both genders?

Selenium is vital for various bodily functions, including reproduction and thyroid function. It plays an essential role in the production of thyroid hormones, which regulate metabolism. Selenium is also important for sperm production and the maintenance of healthy reproductive systems in both men and women. The recommended dietary allowance (RDA) of 55 mcg/day reflects the amount needed to support these vital processes and maintain overall health.

This mineral also acts as an antioxidant, protecting cells from damage, which is crucial for reproductive health. Additionally, selenium's involvement in the synthesis of selenoproteins is key to various metabolic and reproductive functions in the body. Overall, its critical roles in reproduction, thyroid health, and the recommended intake supports its identification as the correct answer in this context.