The small intestine is designed to allow tiny particles of digested nutrients to pass through its wall and into the bloodstream. These are then distributed for use throughout the body. But due to a variety of causes, sometimes the intestinal wall can become more permeable and allow larger, less digested particles and unfriendly contaminants to pass through. The body regards these particles as foreign "invaders", and the immune system attempts to fight them off—which can set the stage for various health challenges.
For this reason, it is important to maintain healthy digestion and healthy permeability of the intestinal wall. The first steps could include promoting a healthy probiotic population and taking digestive enzymes to help support thorough digestion of complex food particles. A good multi-vitamin and multi-mineral is also helpful for providing the gut with the nutrient building blocks to maintain itself.