Zinc, when ingested, forms a complex with picolinic acid which enhances the rate of absorbtion of zinc. The quantity of zinc absorbed is directly related to the availability of picolinic acid which is synthesized from tryptophan. If this conversion is impaired, or there is a deficiency of vitamin B6 which is required for the conversion, then the result will be impaired zinc absorption. Therefore, providing zinc picolinate enables the body to bypass this stage and leads to effective absorption.