Condition such as constipation, diarrhea, SIBO, Crohn's Disease, Ulcerative Colitis, and Leaky Gut all cause issues with absorption of nutrients.  This can lead to faster aging, depression (>70% of seratonin - the "happy hormone" is produced in the lining on the gut, and is disrupted by gut inflammation, etc).  Healing the GI tract is imperative to optimal health -- this can be done with the use of IV therapy, neutraceuticals, herbs, diet and lifestyle modifications.