Nutribiotic Maximum Strength Defense Plus Grapefruit Seed Extract is the most powerful natural product available for enhancing the body's defense system and providing nutritional support for people with certain health concerns.NutriBiotic DefensePlus Tablets contian Citricidal (grapefruit seed extract), a naturally quaternary compound synthesized from the seed and pulp of certified organically grown grapefruit. This unique formulation combines Citricidal, vitamin C, astragalus, and the extracts of echinacea, reishi, maitake, shiitake, ginger root, goldenseal, and yarrow and has been proven hightly effective by healthcare professionals worldwide as nutritional support for individuals with certain health concerns.