Energy. It is the spark of life. Early single-celled organisms created a symbiotic relationship with mitochondria, providing them a host and receiving a continuous energy source in return. As one of the cell?s most critical components, these organelles are also one of the most susceptible to dysfunction. Progressive toxicity?from pharmaceuticals, the environment, pesticides, and even byproducts of their own metabolism?results in fewer mitochondria and a corresponding loss of energy. Without sufficient energy, any organ or system in the body may also succumb to dysfunction. The good news is that mitochondria can be protected and even restored with nutritional therapy.