When I first started supplementing with potassium, I knew I was on to something. My voice noticeably deepened. This effect was more dramatic that anything I had noticed before in my life. However, the effect lasted only a week or so, then it disappeared. After further digging, I discovered that magnesium was required for potassium to be used, supplementing with magnesium and potassium again lowered my voice. Aha, I thought, I'm on to something! You need both potassium and magnesium.
However, after a few months, I again noticed that my voice began to get higher again and no matter how much magnesium and potassium I took, it wouldn't lower again. Until… after considerable experimentation, supplementation of additional zinc caused my voice to deepen once more.
Potassium, Magnesium and Zinc… there's my current regime. However, it must be noted that I was already supplementing with other things: Vitamin A, Vitamin D, the B Vitamins, Vitamin K, Iron and Copper. So maybe some of those factors are necessary too.
I have, however, noticed things that enhance the voice lowering effect. A soup made from steamed carrots, red pepper, celery, rosemary and either butter or edam cheese seemed to boost the effect, making my voice even lower still. However, it seemed to worsen my erectile function. Given that rosemary and perhaps celery have DHT inhibiting effects, there may be a case for dropping those ingredients and replacing them with others.