Many parents of children on the autism-spectrum report seeing black flecks in their child's stool when implementing anti-viral or anti-yeast treatment combined. People have theorized that these black flecks may be heavy metals or viruses detoxifying from the body. To date no one knows for sure. One explanation could be the accumulation of bile acid imbalances from poor liver function, along with cellular debris from the lining of the digestive system from chronic inflammation. Also, the accumulation of pigments from food could give the darkening appearance as well. Overall, it is difficult to say what these black flecks are exactly, but they do seem to occur with detoxification therapy.
White, frothy material - this has been speculated to involve yeast coming out in the stool. This certainly is possible particularly if you look at images of oral thrush (which is caused by Candida). However, it is likely too to be excretion of mucus (or mucus strands), along with sloughing epithelial cells from intestinal inflammation.
The normal appearance of stool should be dark to light brown in color. It may appear at times to be dark green depending on the level of vegetables consumed. Dark leafy vegetables have dark green pigments. If your child consumes beets this will turn the stool dark with almost a burgundy appearance.
Black stools - usually indicates blood in the stool normally caused from bleeding high up in the intestines.
Bright red blood in stools - indicates bleeding from lower in the intestines. One common cause of this is rectal irritation from hard stool, or internal hemorrhoids. If you see blood in your child's stool it is always recommended to inform your child's physician.
Normal pigment process of stools is caused by the breakdown of heme. Heme is part of the porphyrin system, and is involved in hemoglobin production (for oxygen transport throughout the body), as well as cytochrome reactions in the liver for detoxification.
Heme pigment breaks down from red to yellow to green to brown as it passes from the bloodstream to the liver to the upper intestine, and finally down to the large intestine. If stool is colorless this indicates a block somewhere in the initial breakdown of heme. If the stool is green (unless one is consuming large amounts of green powder drinks) it indicates increased transit time through the digestive system.