As simple as taking iron supplements. If your ferritin is 70 ng/ml or higher, you won't notice much benefits on hair. In fact, having high ferritin levels is not good, because it can lead to inflammation and severe damage to the liver and heart.You can even die if you take it without any supervision or if you don't do blood work every 3 to 6 months. I'd only recommend Iron to people with less than 60 ng/ml, and whenever you reach those levels, unless you are vegetarian/vegan or have somehow a low iron intake, stop using it.