Most probably, it is Joe's digestive organelles that have been affected.
All of our body parts need energy to work that we get from food. The food we take is broken down and mixed with different acids and enzymes that help in the process of digestion. When the food is digested, the carbohydrates in the food, which include starch and sugars, are further broken down into glucose. The stomach and the intestines then absorb this glucose and release it into out blood which can be used as energy by our cells or be stored to use later.