You are what you eat... minus what doesn't get absorbed. With Crohn's Disease that can lead to serious problems -- even if you think you are eating a "healthy" diet. Depending on where your Crohn's is active in your intestines, you can wind up with different nutrient absorption problems.
Monitoring the efficiency of nutrient absorption isn't just for people with Crohn's -- today I found an interesting article about the importance of digestive functionality for bodybuilders. This article gives a good overview of the entire digestive process and then goes into some detail about Leaky Gut Syndrome (which just happens to be common with Crohn's disease) and some strategies for preventing Leaky Gut and enhancing digestion.
A recent study showed that even when Crohn's Disease is in remission, you still need to be concerned that you might not be absorbing enough Vitamin D. This is a serious issue since Vitamin D is associated with such good things as keeping your bones strong and healthy, fighting cancer, and fighting colds and flu.
Low Vitamin D levels have long been associated with Crohn's disease, but this study specifically tested how much Vitamin D was absorbed when patients with Crohn's disease in remission were given Vitamin D orally.