Bowel symptoms are a routine part of chronic fatigue syndrome, fibromyalgia and ME (myalgic encephalomyelitis). These are caused by many problems including numerous bowel infections and autonomic nervous system dysfunction.

The autonomic nervous system is what controls contractions that move food in the proper direction going from your stomach toward the colon and anus.

Bowel infections and autonomic dysfunction results in acid reflux, nausea, diarrhea, gas, bloating and constipation — and most people with chronic fatigue have some or all of these symptoms.

Eliminating candida/yeast overgrowth is especially helpful (I recommend candida be treated in almost everyone with chronic fatigue or fibromyalgia), as is treating any parasitic infections which in our study were present in 1/6 of chronic fatigue patients.

Small intestinal bacterial overgrowth (SIBO) is also common in chronic fatigue and is actually aggravated by an underactive thyroid.

What's new is the hypothesis that hydrogen sulfide (which causes a rotten egg smell and is the major reason why intestinal gas sometimes smells awful) is also being produced at toxic levels by certain unhealthy bacteria — and aggravating chronic fatigue symptoms.

It is also hypothesized that the presence of toxic metals (e.g., mercury, nickel, etc.) can make the hydrogen sulfide even more toxic and block energy production in people's mitochondrial energy furnaces.

Hydrogen sulfide is normally found in our bodies at low levels. It is a major part of natural gas (e.g., the gas used in gas ovens). It is usually not toxic at low levels (your body has enzymes to break down small amounts) but can be very toxic at very high levels.

The key question is whether the gut bacteria are really producing enough hydrogen sulfide to be a major cause of toxicity. I have not yet been able to find the data on just how high the hydrogen sulfide levels were in Dr. DeMeirleir's study.

To put this in perspective:

• 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide, normally described as resembling "a rotten egg."

• 2 ppm has been suggested to be associated with subtle medical problems. This is approximately 400 times the level where you will smell it.

• Less than 10 ppm has an exposue limit of 8 hours per day.

• 10-20 ppm is the borderline concentration for eye irritation.

This means that you're going to start smelling hydrogen sulfide at less than 100th of the concentration needed for it to be toxic. This means our nose could supply a wonderful and very sensitive test for the presence of hydrogen sulfide overproduction.