The key to disease is the stomach. This is because so much of our health is controllable through what we eat and drink. Although 100% of the factors in disease are not attributable to what we digest, so much of it is. Eating better and abstaining from alcohol and caffeine can do our health a world of good.
No, the key to disease is not the stomach, because we have to eat something. Cancers have been a problem throughout history and in many places all over the world. This is true even though diets are very different all over the world. The human body is breakable, and sometimes our bodies just become diseased.
No, the stomach is not the key to disease because diseases can affect any portion of the human body. While many illnesses can be attributed to the stomach, not all can be, and to narrow the focus down to only one area of the body seems like a closed-minded idea.
I believe it is wrong to assume that the key to disease is the stomach. The medical field knows this is not the case because diseases come with quite a bit of variety. Not all illnesses are directly linked to the stomach and modern medicine tells us this fact. There's no point in debating it.