Dietary Supplement Dr. Michael Murray Formulated Purity & Potency Guaranteed The Ultimate Antioxidant is a nutritional supplement designed to provide a powerful boost to antioxidant processes in the body. For maximum benefit, take with the appropriate MultiStart multivitamin formula from Natural Factors. All Natural Factors products are manufactured in accordance with the Government of Canada's Good Manufacturing Practices (GMP), among the highest standards in the world.