The dose was 100mg elemental zinc for 3 months. Zinc inhibited NO synthesis from arginine. Combined with magnesium, zinc could be a viable alternative to methylene blue - magnesium for getting NO out of the cell and thus restoring cytochrome C activity, and zinc inhibiting new NO synthesis.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3882288/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3882288/