So how do they work? Our bodies naturally contain a host of vitamins and minerals but depending on genetics, lifestyle, pregnancy and any number of other factors, we can become deficient. Supplements containing vitamins or minerals serve as a top-up, bringing our levels back to normal. Anything over the percentage our body can take is usually urinated out. For example, Dr. Selezneva says, "To reach a sufficient amount of glutathione, the mother of all antioxidants, you would have to eat at least 3kg of asparagus, which has the highest amount of glutathione compared to any other food. The way around this if you are deficient would be to simply take a prescribed dose." For patients with long-term medical issues, she recommends a baseline blood test to find the deficiency before prescribing the relevant supplements.