Since the Feingold hypothesis involves the elimination of multiple items, then the multiple items need to be eliminated to test it. The Feingold membership materials and Foodlists should be used since the test would then be of the Feingold diet as it currently exists. Testing a 3-food diet is a valid test of a 3-food diet, but it is not a test of the Feingold diet.
Since the Feingold hypothesis involves the elimination of multiple items, then the multiple items need to be used in the challenge materials to try to provoke a behavioral response in the double blind portions of the study. If a single-item challenge does not provoke symptoms, it means little, since the interactions of several items may be needed to do so.
When administering challenge materials, behavior should be monitored periodically beginning one-half hour after ingestion, and ending four to six or more hours later. A single evaluation four hours after ingestion may totally miss the reaction, especially with food dyes (Adams, 1981; Swanson, 1980).
When administering challenge materials, the level of such materials should be reasonably large, not to miss the "Halloween effect," or what happens during other periods of excessive consumption during birthday parties and holidays.
When administering challenge materials, the time period of administration should be long enough to overcome what FAUS calls the "washout effect," where a child established on the diet does not react to a single infraction and can "get away with" cheating if not done frequently. Several days in a row should be adequate.
Arrange to avoid cheating. Cheating twice a week may be enough to prevent improvement (has the alcoholic recovered if he only gets drunk twice a week?)
Since the Feingold diet is administered and adjusted individually, some provision for doing that should be included in the study. It is not a one-size-fits-all program.
The researcher must be vigilant against confounds like coloring in non-food items such as for skin care, finger paint or play dough, environmental toxins such as pesticides, fresh paint, or fragrances, etc., as outlined in the Feingold Handbooks (1982, 1996, 1998).
The researcher should be aware that children recently on psychoactive medication may take up to six weeks to respond to diet therapy (Feingold Assoc, 1982, 1996, 1998). The reason for this is not known. They should either be given an extended washout period or not be used in the research.