Our Vitamin C formula provides you with 250 mg of vitamin C in each tablet. Vitamin C is an antioxidant that helps support the immune system and helps neutralize free radicals in the body.? 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.