Our Zinc supplement provides 15 mg of zinc as zinc gluconate per tablet. Zinc is an essential mineral that helps supports a healthy immune system and is also promotes for normal growth and development.? For additional formula information, view the Supplement Facts panel. All Windmill supplements are manufactured in the United States in an FDA-inspected facility whose GMPs (Good Manufacturing Practices) are independently verified by qualified certification organizations. Free of artificial colors, flavors and preservatives, Windmill is a trusted name that has been providing America with quality supplements for over 40 years.