Section 4K. Any subscription certificate under an individual or group medical service agreement that shall be delivered, issued or renewed in the commonwealth shall provide, as benefits to all individual subscribers and members within the commonwealth, all group members having a principal place of employment within the commonwealth and all persons included in section four C, coverage for nonprescription enteral formulas for home use for which a physician has issued a written order and which are medically necessary for the treatment of malabsorption caused by Crohn’s disease, ulcerative colitis, gastroesophageal reflux, gastrointestinal motility, chronic intestinal pseudo-obstruction, and inherited diseases of amino acids and organic acids. Coverage for inherited diseases of amino acids and organic acids shall include food products modified to be low protein in an amount not to exceed two thousand five hundred dollars annually for any insured individual.