Candida overgrowth in the intestines is linked to depression. Candida is of the fungus family, and is not as easily eradicated as a viral or bacterial infection. Many patients diagnosed through their Naturopathic or Alternative Doctor as having candida, see improvement in mood and sleep as a benefit of following a candida cleanse or diet. I have seen this personally many times. It is hard to explain the relationship 100 percent, but they are some interesting correlations to where yeast predominantly grows and where serotonin is produced. Candida is a normal inhabitant of the intestinal tract. Its presence and expression is normally controlled by a clean diet, and naturally occurring probiotics as found in fermented foods. The use of antibiotics, stress, and soda result in the over expression or growth of candida in the intestinal tract. Candida has also been linked to fibromyalgia, chronic fatigue, and even some auto-immune conditions. Interestingly enough, serotonin as measured in blood or urine samples, is produced predominantly in the enterochromaffin cells of the small intestine, where yeast can possibly dominate. It is my theory that yeast presence reduces total serotonin in circulation, by an affect on these intestinal cells. This has been observed in lab work in which antibodies to candida are seen as well as low levels of serotonin in circulation in many of my candida diagnosed patients. Candida is not easy to reduce in the intestinal tract and often requires strong prescriptions or aggressive natural medicines in order to eradicate. Most general practitioners do not recognize this relationship and will fail to support the use of anti-fungal therapy as a means to improve depression. Seek an alternative physician for professional guidance on how to treat candida and possibly improve depression, fatigue, and sleep disorders quickly through affective candida protocols.