Any kind of digestive or gastrointestinal problem will diminish your absorption of vitamins, minerals, protein, essential fats, and plant substances required to maintain a healthy body. Irritable bowel syndrome, colitis, Crohn’s disease, or chronic diarrhea hurt your ability to absorb nutrients. Ditto for bacterial, viral, yeast or parasitic infections. Food allergies are notorious for causing GI problems. In short, any inflammation in your GI tract means trouble. Therefore, you will need supplements to help you deal with the inflammation, as well as to increase the amount of essential nutrients you are consuming and absorbing.