Pure Encapsulations Thyroid Support Complex is a comprehensive thyroid support formula that contains vitamins, minerals and herbal extracts to nourish and support thyroid gland function. It may also promote healthy lean body composition. Research indicates that ashwagandha and guggul are also key factors for helping to sustain healthy thyroid function. Doubling as powerful antioxidants, vitamins A and C, selenium and guggul combine with curcumin to neutralize free radicals that affect iodothyronine 5′-monodeiodinase enzyme activity, the limiting factor in the conversion of T4 to the more active T3 hormone.