In cases where a person suffers from a disease, belief in the efficacy of a detox diet can result in delay or failure to seek effective treatment. Detox diets can involve consuming extremely limited sets of foods (only water or juice, for example, a form of fasting known as juice fasting), eliminating certain foods (such as fats) from the diet, or eliminating processed foods and alleged irritants. Detox diets are often high in fiber. Proponents claim that this causes the body to burn accumulated stored fats, releasing fat-stored "toxins" into the blood, which can then be eliminated through the blood, skin, urine, feces and breath. Proponents claim that things such as an altered body-odor support the notion that detox diets have an effect. The mainstream medical view is that the body has mechanisms to rid itself of toxins, and a healthy diet is best for the body. Although a brief fast of a single day is unlikely to cause harm, prolonged fasting (as recommended by certain detox diets) can have dangerous health consequences or can even be fatal. Colon cleansing involves administration of an enema (colonic) containing some salt, and sometimes coffee or herbs to remove food that, according to proponents, remains in the colon, producing nonspecific symptoms and general ill-health. However, the colon usually does not require any help cleaning itself. The practice can be potentially dangerous if incorrectly practised. Practitioners may recommend detoxification as a treatment to address the notion that mercury poisoning arises from consumption of contaminated fish and from dental amalgam fillings – Quackwatch states: "Removing good fillings is not merely a waste of money. In some cases, it results in tooth loss because when fillings are drilled out, some of the surrounding tooth structure will be removed with it." Certain devices are promoted to allegedly remove toxins from the body. One version involves a foot-bath using a mild electric current, while another involves small adhesive pads applied to the skin (usually the foot). In both cases, the production of an alleged brown "toxin" appears after a brief delay. In the case of the foot bath, the "toxin" is actually small amounts of rusted iron leaching from the electrodes. The adhesive pads change color due to oxidation of the pads' ingredients in response to the skin's moisture. In both cases, the same color-changes occur irrespective of whether the water or patch even make contact with the skin (they merely require water—thus proving the color-change does not result from any body-detoxification process).