Some people are afraid of taking activated charcoal because one normally associates charcoal with a dirty-looking stuff used to make a fire. But in reality, it’s been used for hundreds of years as a digestive cleanser. Here is some research info I’ve found on activated charcoal. I understand it to say that it absorbs toxins (that could emit odor) and eliminates it through your bowels. I would think that this would have to help with fecal odor. If your body is building up odor-producing toxins from poor digestion or infection, then activated charcoal absorbs these toxins and eliminates them with your bowel movement. By doing so, it also absorbs the odor and eliminates it.
I know that activated charcoal is used in very high doses in hospital Emergency Rooms with most drug overdose cases.
In http://www.emedicinehealth.com/activated_charcoal/article_em.htm, it says that activated charcoal is a very safe decontaminant in the gastrointestinal (GI) tract (stomach and intestines). It is considered to be the most effective agent available, and is used after a person swallows or absorbs almost any toxic drug or chemical.
Activated charcoal is estimated to reduce up to 60% of poisonous substances being absorbed.
It works by adsorbing (soaking up) chemicals, thus reducing their toxicity (poisonous nature), through the entire length of the GI tract (stomach and small and large intestines).
Activated charcoal itself is a fine, black powder that is odorless, tasteless, and nontoxic.
Activated charcoal is often given after gastric lavage—the technique often called the stomach pump. Gastric lavage is only effective immediately after swallowing a toxic substance (within about one-half hour) and does not reach beyond the stomach as activated charcoal does.
The Mayo Clinic has similar information re activated charcoal http://www.mayoclinic.com/health/drug-information/DR602267
The following article in a Nursing journal, http://findarticles.com/p/articles/mi_qa3689/is_200009/ai_n8905056, says that, “Activated charcoal, an adsorbent that's capable of binding many substances in the GI tract, is generally considered the most effective agent for preventing the absorption of ingested toxins into the bloodstream. Once it binds to a toxin, the toxin adsorbent complex is expelled is the stool. However, not all substances are well adsorbed to activated charcoal… Activated charcoal has an advantage over other gut decontamination methods because it can "catch up" to substances that have moved beyond the pylorus into the small intestine. It can bind up to 60% of a toxin when given within 30 to 60 minutes after the ingestion.”
It also goes on to say that, “Even when certain toxins have been absorbed into the bloodstream, multiple doses of activated charcoal, sometimes called "gut dialysis," can help increase their elimination. An adult may receive 12.5 grams/hour of activated charcoal until his drug levels reach nontoxic levels, typically within 24 hours. The drug is eliminated through a process of back dif fusion from the mesenteric capillaries across the GI epithelium into the GI tract, where it's adsorbed to the charcoal.”
Hope this helps with the fecal breath or body odor.