Are Self-Diagnosed Food Allergies Causing Malnutrition?

The tests you need for confirmation are simple....

Posted Mar 27, 2018

Anyone who has been either a dinner party host or guest over the last few years will recognize the eater who can’t eat. Or, more precisely, who must pick and choose the foods that can be eaten with the care of someone traversing a field of cows. A friend of mine had as a house-guest a young woman with multiple real (or imagined) food allergies: gluten, dairy products, fish, all nuts except almonds, fruits, grains, and potatoes. According to my friend, all the guest allowed herself to eat was chicken, chicken, and more chicken. 

“I hope she was taking a vitamin pill,” was my response, “and maybe some calcium supplements as well. Her diet sounds like a perfect storm for malnutrition.”

Nutritional deficiencies have been detected for decades among people whose life-style, economic status and (sometimes) digestive limitations have severely restricted food intake. The Sunday New York Times magazine recently had an article about a patient who developed scurvy from lack of vitamin C because gastric reflux caused him to eliminate all citrus fruits and other fruits with substantial vitamin C content. Elderly individuals may lose the ability to absorb Vitamin B12 into their circulation and, as a result in severe cases, they can develop cognitive deficits. Other vitamins deficiencies like folate or folic acid, Vitamin D, and Vitamin C may also be inadequate, especially among those who live alone and rarely prepare and eat nutritionally adequate meals.  

Risk factors for nutritional deficiencies (such as aging or prolonged chemotherapy with its resultant inability to eat due to mouth sores and nausea) may also occur. A friend going through chemotherapy developed such severe mouth sores that she had trouble swallowing even liquid meals. She developed a potassium deficiency and nearly died. But usually such nutritional deficiencies are anticipated. For example, patients in the early post-operative months following bariatric surgery who can eat only tiny quantities of food are advised as to how to obtain the nutrients they need through fortified liquid foods and/or supplements. 

The possibility of nutritional deficiencies is also likely among people who believe they have food allergies based on what they read or hear, rather than the results of standard tests of allergic reactions to known allergens. The chicken-only houseguest kept adding to the list of foods she would not eat not because of any physician diagnosed food allergies, but based on information she gleaned from the Internet. She believed she felt better not eating the long list of foods she termed, “allergic.” Maybe this was real; maybe it was a placebo effect. The standard way of finding out is through testing for allergic responses, and the testing is done without the patient knowing which allergen is being tested. 

Malnutrition from self-diagnosed allergies may seem fanciful, but it is a real concern for pediatricians. Infants may develop allergic responses at a young age, as do older children. The most common foods that provoke allergic reactions are eggs, milk, soy, wheat, peanuts, fish, and shellfish. When these are suspected and confirmed by testing, the physician is able to recommend other sources of the essential nutrients the child needs. Thankfully, there are nutritional products developed to ensure the normal growth of the allergic child. But according to an article by Mehta, Groetch and Wang, doctors are seeing an increase in the cases of parents diagnosing allergies in their children themselves without confirmation by allergen testing. The diets of these children become nutritionally deficient and cause failure to thrive, along with diseases like rickets, due to the lack of essential vitamins and minerals.

The authors cite their concern, for example, over how children are to get enough calories and essential vitamins if the parents decide that their child has a wheat or gluten allergy. Complex carbohydrates are supposed to provide about half the calories needed by the child each day for energy.  Taking away all grains not only reduces energy intake, but also decreases the supply of essential nutrients such as thiamine, niacin, riboflavin, iron and folic acid. Obviously, if a physician detects the allergy, then other sources of nutrients and calories will be recommended. But are the parents who decide for themselves to eliminate grains, for example, knowledgeable enough to make sure their child is getting enough calories and nutrients?

Fortunately, children who go to school must have contact with a physician on an annual basis, or at the very least before starting school, so nutritional deficiencies and their effect on growth may be noted at that time. 

But is anyone monitoring the nutritional status of adults young and older who self-diagnose their food allergies?  If this young woman is seen annually for a wellness checkup, she may be asked what she eats, and also about her food allergies. Would she then be referred to a dietician to develop a nutritionally adequate diet around the limited food choices the patient allows herself? Would the long-term consequences of avoiding foods we are told to eat as a source of the myriad nutrients our body’s demand be pointed out to her? Or might she end up in the pages of a Sunday magazine medical article because of an interesting nutritional deficiency?

At the very least, someone who claims to have several allergies should be given the opportunity to undergo standard testing for allergic reactions. The testing will not only reveal which allergies she has, but which ones might be dangerous, and which may be tolerable.


(“Growth and Nutritional Concerns in Children with Food Allergy,” Mehta, H., Groetch, M., Wang, J., Curr Opin Allergy Clin Immunol 2013; 13:275-279)