Cristiano Ronaldo uses black nail polish for foot health

Cristiano Ronaldo’s habit of wearing black nail polish is a functional health measure rather than a fashion choice. The practice is intended to protect his feet from fungal and bacterial infections, which are common risks for professional athletes who spend long hours in tight, humid, and sweaty footwear.

This method is also utilized by athletes in high-impact sports like boxing and MMA to act as a thin protective layer, increasing nail hardness and reducing the risk of cracks or splitting during physical contact. Boxing legend Mike Tyson has previously noted using a similar approach. While the Royal College of Podiatry in the UK has noted that small studies suggest nail polish can act as a barrier against bacteria, medical consensus on its absolute effectiveness remains varied.