the most prominent reasons. * Duro Max Supplements are not regulated by the FDA Because there are no purity standards enforced by the FDA, companies can put the smallest amount of ingredients inside of a blend, and you have no way of knowing if it will deliver on its promise. At most, you only know that it contains the ingredient. The most important factor, however, is how much of that ingredient does it contain. Clinical trials use a strict dosage to test how effective an .