Foundational Immune Support. Thorne Zinc Picolinate 15 mg provides an essential micronutrient that is crucial to more than 200 enzymatic reactions. The best-absorbed Zinc, Zinc Picolinate, plays a key role in growth, immune function, testosterone metabolism, and other body functions. As a result, zinc supplementation can increase general wellness and have a beneficial impact on connective tissue. This supplement is gluten-free.