DEAR DR. BLONZ: There has been no clear clinical evidence that food causes behavioral issues in children. I am interested in your thoughts on this issue. -- R.D., Los Angeles
DEAR R.D.: The role of food allergies in childhood behavior remains controversial, but it is not unreasonable to at least consider this as a possibility when other avenues have been unproductive. It is essential, however, that one proceeds cautiously, calling upon a clinician experienced in this area.
One issue is that the connection between the behavior and the offending substance(s) might not be readily apparent. You have to consider what happens if the wrong substance is blamed, or if one simply turns to generalities, such as blaming all food additives. Such cases can give rise to changes in parental behavior that can then act as programming for the child: "You shouldn't eat that, it will make you sick." It can all turn into a march down an unproductive road with ever-growing limits placed on the child's ability to eat and enjoy life.
The ironic thing is that a parent might observe improvements in a child's behavior even if the wrong substance is identified. Such changes might take place because they are expected -- the essence of the placebo effect. You haven't accomplished much if the underlying problem was not allergy-related or if it was caused by an item not originally suspected. If the symptoms resurface, other foods or food categories might get added to the "banned" list, further restricting the child and the parents.
I raise this scenario to highlight the importance of a reasoned, systematic approach. Parents can assist the process by maintaining a diary of foods consumed and reactions observed; this aids the experienced health professional in compiling a list of the likely suspects for further testing.
Once suspects are identified, testing in a controlled clinical environment is essential to remove any possible bias from all concerned parties. A gold-standard often relied upon is the double-blind, placebo-controlled food challenge. I would encourage you to discuss this with a physician. I often refer people to an excellent review article, "Manifestations of Food Allergy: Evaluation and Management," which appeared in the January 1999 issue of American Family Physician.
DEAR DR. BLONZ: One of my favorite times of year is when the new crop of potatoes comes to the market. My question has to do with the nutritional value of these fresh potatoes. I checked the USDA database, which says that a medium-sized baked potato, or a similar amount of French fries, is supposed to contain about 17 milligrams of vitamin C. You have mentioned that heat destroys vitamin C, among other nutrients. If this is the case, how can these "heated" potatoes still be a good source of vitamin C? -- J.J., San Diego
DEAR J.J.: The high heat involved in the preparation process does indeed destroy a number of vitamins, including vitamin C and thiamin (vitamin B1). That level of vitamin C does reflect a reduction from the amount in the raw potato. French fries will have a bit less due to their increased surface area.
A good source for any nutrient is one that provides between 10 and 19 percent of the daily value for that nutrient. An excellent source is one that provides at least 20 percent of the daily value. Seeing as the daily value for vitamin C is 60 milligrams, one serving of "heated" potatoes would actually be an excellent source.
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