Provided by the present invention are novel and non-obvious nutrient supplements that preferably comprise minerals, vitamins, amino acids, and agents capable of delivering cysteine in vivo. The nutrient supplements desirably are capable of promoting metallothioneins, and optionally, promoting the removal of excess metals from the bloodstream. Also provided by the invention are methods of treating autism involving administration of the nutrient supplements. The methods include treatment to prevent or slow down the onset of autism once a predisposition for the development of autism has been detected, and treatment to alleviate or reverse the symptoms of autism once autism has been diagnosed. The invention further provides methods of administering the nutrient supplements in the treatment of other diseases, disorders and conditions, that would benefit from such administration, especially those that would benefit from metallothionein promotion and/or removal of excess metals from the bloodstream.