A 51 year old man started the Atkins diet as a healthy person. He had low cholesterol, no arterial blockage, no chest pain and no erectile dysfunction. 29 months after starting the Atkins diet, he ended up requiring a stent in his heart and Viagra. After his stent surgery, he changed his diet to a low fat vegan diet and reversed his heart disease and his erectile dysfunction, meaning he no longer required Viagra to get an erection. Case study can be found here.