Dr. Rosemary Waring found that most people with autism have a deficiency in a key detoxification pathway. The pathway involves using sulfur in the form of sulfate (known as sulfation). The enzyme involved is phenol sulfur-transferase (PST), but the problem is thought to hinge on an inadequate supply of usable sulfate ions, not the metabolic enzyme itself.
Dr. Waring found that most children on the autism spectrum are very low in sulfate and may be as low as 15 percent of the amount in neurologically typical people. People with low or no ability to convert compounds to sulfate have problems handling environmental chemicals, some medications, and even some chemicals produced within the body.
The PST sulfation pathway is necessary for the breakdown and removal of certain toxins in the body. This includes the processing of a type of chemical called a phenol. Phenols are a regular and necessary part of life. All foods contain some phenolic compounds. However, some foods have a much higher phenol content than others. If the sulfation pathway is not functioning well, a person may not be able to process out the phenolic compounds as fast as they consume them. There is a cumulative effect. When the phenols start backing up in the system, it can cause a myriad of negative reactions. Symptoms of phenol intolerance include night waking, night sweats, irritability, eczema, and other skin conditions. The symptoms of phenol intolerance and yeast may be very similar because they both involve the body trying to deal with toxins.
This detoxification pathway processes other phenolic compounds, including salicylates (salicylates are a subset of phenols), artificial food colourings, artificial flavourings, and some preservatives. Besides requiring PST, research has found the salicylates further suppress the activity of any PST enzyme present, making matters worse. Food dyes have also been shown to inhibit the PST enzyme.
You can unclog this 'bottleneck' in one of two ways. One is reducing the amount of phenols and toxins entering the body. This is the basis of the Feingold Program or diet.
The second method of enhancing the detoxification process is to supply more sulfate. This increases the amount of toxins processed out. Sulfate ions may not be absorbed well from the gut, so simply giving more sulfur directly by swallowing supplements may not produce satisfactory results. Some people have seen improvements by supplementing with the sulfur-containing amino acids cysteine and taurine, or MSM (methysulfonylmethane), or by using one of the many commercially available MSM creams. However, others have found this intolerable, possibly because their body are unable to convert the sulfur to the needed sulfate form.
Most people do see improvement with Epsom salts because the form of sulfur in the Epsom salts is already sulfate and is readily available to the body.