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Food Allergies
By Dr. Todd
We are now offering the LaCrosse Allergy Associates Food Drop Protocol. This allows us to tap into their experience and expertise in treating Food Allergies.
Adverse reactions to food are a common complaint facing all physicians. There is both public and professional confusion on the extent and classification of the entity as well. Some of this confusion stems from the variety of mechanisms and effects that ingestants can have on people. These adverse reactions may be either immunologically or non immunologically mediated and can result in signs and symptoms ranging in severity from mild to life threatening anaphylaxis. Although the majority of severe reactions are thought to be immunological and mediated via IgE, other immune globulins, such as IgG and IgA, may play a role in some people as well. Certainly, there are a large number of non-immunologic reactions to foods we simply lump under the term intolerance. In addition, as physicians our training in nutrition is lacking and the American diet can be downright unhealthy.
There is little controversy about IgE mediated (oral allergy syndrome or anaphylaxis), or what some term fixed food allergy. We see it so commonly and recognize it because we are able to directly test for it with blood tests or skin tests. If we isolate our definition of food allergy to type 1 hypersensitivity reactions, then public perception of the problem far super cedes reality. Public perception is that 25 percent of people have food allergies. In reality, the numbers are much lower, with only two percent of adults having this reaction and six to eight percent of infants/children having such response. Among adults, the most severe response is to peanuts, tree nuts, fish and shellfish. Among children, the offending food item is primarily milk. Other culprits in children include soy, egg, wheat, peanuts and tree nuts. The bad news for children is that they often have more skin reactions to foods, such as eczema, than do adults. But the good news for the young patient is that, other than peanut and shell fish, most children tend to outgrow their food sensitivities over time. Unfortunately, as food allergies fade, inhalant (e.g., dust, ragweed) allergies often become more prominent. This progression from food allergies to inhalant allergies and then finally asthma is often termed “The Allergic March”. Of course there are the non-immunologic reactions to food. These too are fairly well understood. The food might be toxic, caused by bacterial poisoning, heavy metal poisoning, or selected fish poisoning. Non-toxic factors include lactase deficiency, gallbladder/liver disease, anorexia, and pancreatic insufficiency. Collectively this group of disorders is termed Food Intolerance. The controversy comes with other very symptomatic patients that do not fall into the above categories. Most of us who see a lot of these patients sort of suspect that there is more to the story. We know of many various disease states such as protein induced enterocolitis and gluten sensitive enteropathy where there is a clear non IgE immunologic reaction to foods. IgM (which does not cross the placenta) to cows milk has been readily found in serum of 1 week olds. And, we have all seen the child with fairly low IgE antibodies to cow’s milk, who responds dramatically to dietary elimination.
Our frustration comes from both our lack of available tests as well as our lack of treatment options. Over the years people are trying varieties of symptom provocation and then neutralization tests, and are now trying various IgG tests for food allergies based on the theory of cyclic food allergies. Although some of the observational research is compelling, there is no good double blinded randomized prospective data or serologic data as of yet to support these tests. So we are left with the history and looking at IgE mediated reactions to help guide our therapy. The therapy, which is the other area of frustration, is really limited to avoidance. Again, many forms of immunotherapy and neutralization have been tried but remain unproven.
The limited utility of laboratory and skin testing in these cases requires us to really to listen to our patients. This takes time and patience to work through dietary strategies. I find it a reasonable strategy is to test refractory children with skin or selective blood testing while under anesthesia. Especially if they are there for their 2nd or 3rd set of tubes or refractory sinus problems. This often allows us to develop dietary strategies which lessen their upper airway congestion. So often we see a child switch to soy milk with minimal improvement because they are also soy allergic. In older children and adults with concomitant inhalant allergies, we find that aggressively treating those helps lessen the food allergy symptoms. Anti IgE certainly has a role in patients with life threatening reactions. If there is a positive family history for food allergies, then the first prevention steps should take place at birth. As breast feeding is generally protective of allergy, the longer nursing can continue the better. Afterwards, efforts should be made to wean/supplement with extensively hydrolyzed hypoallergenic protein hydrolysate. Ideally, the infant should have at least a six month delay in consuming solid foods; should be between six and 12 months old before consuming cow’s milk and dairy and products; be between 12-24 months old before being offered eggs, and be between 24-28 months of age before peanut, tree nut, and seafood is introduced. As the parent of five, I realize this may be wishful thinking. In conclusion, our current treatment options are avoidance, education, and preparation for emergencies. As physicians we need to treat only based on evidence based principles, however, we also need to listen to our patients. We must realize that in regards to food allergies, what we do not know is far more than what we do know. There are many mechanisms whereby dietary modifications can positively affect the health our patients. My bet is that we will be doing things totally different in 10 years. Please see our Section on Allergies.
