Polly: There are many different sulfotransferase enzymes in the body that need an adequate supply of sulfates to attach to other molecules. One very important sulfotransferase enzyme is the one that attaches sulfate to phenol compounds, called phenol-sulfotransferase (PST). Without the PST enzyme working properly, the liver will have trouble eliminating the phenols in food. Phenols are present in food dyes, in highly colored fruits and vegetables, in bioflavonoids, and in cartenoids (carotene, lutein, lycopene, xanthophylls, and zeaxanthin). Eliminating the yeast overgrowth may also reduce the burden of phenolics on the body. Yeasts and fungi in the intestines can produce phenolics.  Phenolic compounds are also found in many foods that contain salicylates. Phytoestrogens are also phenolics. Therefore, eliminating the yeast, and avoiding the phenols, salicylates and phytoestrogens in food may reduce the strain on the PST enzyme. Making sure there is enough magnesium should help the functioning of the PST enzyme.  Yet you must be careful with the B6. Too much coenzyme B6 can suppress phenolsulfotransferase.  However, Dr. Waring found that this effect is mitigated if more magnesium is given.
To protect the PST enzyme, it is particularly important to reduce exposure to salicylates, excessive bioflavonoids and phytoestrogens. Many of these suppress the enzyme P-form phenol-sulfotransferase. 
If you wish to avoid salicylates, there is a comprehensive list of foods that contain salicylates in Dr. Paul St. Amand’s book on fibromyalgia. Or you can find this list of foods at http://www.netromall.com/guai-support/sal-full.htm. If you want to help the body get rid of salicylates, Hope for Autism through Nutrition The Health Forum—Book 5 48 you might try increasing glycine and making sure the urine is alkaline during at least part of the day.
In cases of acute salicylate poisoning, doctors give charcoal to absorb the salicylates in the intestines. They also alkalinize the pH of the urine. (An alkaline urine facilitates the removal of salicylates, whereas an acidic urine interferes.) To alkalinize the urine, they first correct the serum potassium levels then administer sodium bicarbonate (baking soda) to make the urine pH alkaline. However, most of us are dealing with a long-term problem. For long term use, a more balanced bicarbonate like tri-salts may be appropriate. (See the chapter about pH and acid/alkaline in Book 3.)
In acute salicylate poisoning, doctors also administer the amino acid glycine to help the liver prepare the salicylates for removal. For general salicylate detoxification, there is a Dr Vera product that uses a mixture of the amino acid glycine and branch chain amino acids. (See http://www.orthoplex.com.au/prodserv.htm.) I don’t know why the branch chain amino acids are included in this formula. However, if a branch chain deficit exists, correcting may be helpful.
Many of the autistic and the ADD/ADHD people must follow a diet similar to the Feingold diet, which eliminates most salicylates and phenols. However, like so many things, it is somewhat individualistic in its implementation. There are many different types of phenolic compounds, and a person might not be sensitive to all of them. For instance, bioflavonoids are polyphenols. I’ve heard that most autistics cannot tolerate the bioflavonoids in milk thistle, but some can tolerate the bioflavonoids in pycnogenols (eg grape seed extract or pine bark extract). Certain colors in vegetables may be tolerated and others not tolerated. Eg, green may be okay, but not red or yellow, or some other combination. The list of tolerated foods can be quite different for each child. People recommend eliminating all the phenolic foods and then reintroducing them one at a time to see what is tolerated.
There is also a digestive enzyme product made by Houston Nutraceuticals that might help. Their No-Fenol product helps the body remove carbohydrates from phenolic compounds and this may make it easier for the liver to remove these phenolic compounds. This is their website, http://www.houstonni.com and their phone (866) 757- 8627 or (510) 549-4548. There have been a few anecdotal reports of this product helping with the red cheeks and ears that are sometimes present with autism. Initial reports are very favorable.
Robert J. Sinaiko, MD explains a reason that the PST deficit could cause behavior problems.
Certain areas of the brain appear to lack the glucuronidation pathway, and in those areas deficient PST activity might allow the accumulation of toxic phenolic compounds. 
Since glucuronidation also removes phenolics, it is important to support the glucuronidation system in the body. Glucuronidation cofactors are the nutrients L-glutamine, aspartic acid, iron, magnesium, B3 (niacin) and B6. Thyroid should be adequate. Cruciferous vegetables are helpful.  Glucuronidation efficiency can be improved by calcium-d-glucarate. However, you have to start very gradually with the calcium-d-glucarate, and be very consistent. (See the chapter on liver health in book 1.)
Willis: The PST (phenol-sulfotransferase enzyme) is underactive in the majority of autistic children. PST is a Phase 2 liver enzyme that detoxifies leftover hormones and a wide variety of toxic molecules, such as phenols and amines that are produced in the body (and even in the gut by bacteria, yeast, and other fungi) as well as food dyes and chemicals. The enzyme links an Autism Interventions 49 oxidized sulfur molecule (a sulfate) to these substances to solubilize them so the kidneys can dispose of them. Obviously, if sulfate is low or missing this can’t happen effectively. Hence, the problem can be two- fold: there may be a lack of phenol-sulfotransferase enzymes, or there may be a lack of the sulfates (due to the absence of or to the poor absorption of amino acids in the diet, or due to a failure to metabolize them into sulfate form). Dr. Rosemary Waring believes the lack of sulfates is the primary problem.
Since sulfur intake is low, and its oxidation is slow in many autistic children, any foodstuff that requires or uses up sulfate ions during its metabolism, will make the situation worse. These foodstuffs include apple juice, citrus fruit juices, chocolate, and paracetamol (TylenolTM). Blueberry extract, and grape seed extract, and other things have phenols, salicylates, and other stuff that are normally detoxified by PST. For instance, one or two minutes after a dose of TylenolTM, the entire supply of sulfate in the liver is gone! In fact, any chemicals with a high proportion of phenolic groupings will have this effect, and will enhance the problems referred to above. Many coloring materials, whether of natural or synthetic origin, possess phenolic groupings. For this reason, some practitioners recommend the removal of all pigmented foods from the diet (Sara’s Diet). You must at least reduce juices (or limit to a little pear juice), and eliminate all artificial colors and flavors.
Following the Feingold diet plan will benefit these kids by exclusion of foods known to include phenols, salicylates, dyes, and such. For a small membership fee, The Feingold Association will provide a listing of foods to avoid, as well as a continually updated list of safe foods. Their address is: Feingold Association of the United States, PO Box 6550, Alexandria, VA 22306, 1-800-321-3287.
Symptoms of PST/sulfate deficiency are reddened ears, night sweats, black under eyes, excessive thirst, facial flushing, and odorous bed clothes. Certain foods may cause fevers, and some, especially those taking ParacetamolTM (TylenolTM), may go up to 24 hours without urination.