Hello,
It is natural to find darkened genital and scrotal area in some men and there is no abnormality in it. It is not due to any nutritional deficiencies. This darkening occurs when an excess of melanin, the brown pigment that produces normal skin color, forms deposits in the skin.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.