This is a relative newcomer to food sensitivity disorders, and it affects less than 1% of infants. Known by its acronym F.P.I.E.S., Food Protein-Induced Enterocolitis Syndrome occurs due to a non-allergic immune sensitivity to certain food proteins that triggers vomiting.
Symptoms of FPIES
FPIES has a very classic and predictable pattern. Severe vomiting occurs about two hours following ingestion of the reactive food. It will seem as if the victim is experiencing food poisoning. Repetitive vomiting will persist for an hour or two, and diarrhea will sometimes start after that. In many cases symptoms will resolve without any treatment as the reaction runs its course.
Some cases, however, will progress into a shock-like state from a drop in blood pressure; the patient can become pale, lethargic, and appear severely dehydrated. It’s as if the person is having an anaphylactic reaction without the classic skin signs of itching, hives, swelling, and wheezing. Although fairly uncommon, such reactions require a trip to an emergency room for intravenous hydration and stabilization.
Cause of FPIES
Instead of the classic IgE type of allergic reaction, researchers suspect it is the T-lymphocytes that react to a small number of specific food proteins and trigger a delayed reaction. Infants are likely born with a genetic susceptibility to FPIES, although we don’t yet know which genes are responsible or how to predict who may be at risk.
Foods that have been found to trigger an FPIES reaction include (in order of commonality):
- Rice
- Oat
- Wheat
- Barley
- Sweet potato
- Banana
- Poultry
- Peas
- Green beans
- Squash
- Fish
Cow’s milk or soy infant formula can also trigger reactions; proteins passing through mom’s breast milk can very rarely cause FPIES reactions.
Diagnosing FPIES
Interestingly, food allergy tests are usually normal in these children and don’t help identify the offending foods. Endoscopy is usually not necessary; when done, it will often reveal inflammation within the GI tract.
The diagnosis is primarily made by observing the pattern of the reactions. FPIES presents with the following unique features which easily distinguish it from GERD (reflux), the stomach flu, classic allergy, or food poisoning:
It begins between 3 and 7 months of age. Most infants are born healthy and have no feeding problems during the first few months. Then, the first episode of intense vomiting suddenly occurs. GERD, on the other hand, usually begins within the first few weeks.
It is episodic. Repetitive vomiting occurs for an hour or two, then resolves. After recovery, the infant will appear well until the food is consumed again. Spells will continue until a diagnosis is made. Food poisoning or a stomach flu, which can be confused with FPIES, occur only once every few months or longer.
It predictably occurs about two hours after a feeding. GERD, or infant reflux, tends to occur right after a feeding, whereas the immune reaction in FPIES takes about two to three hours to build up after eating the food.
It occurs after the first or second feeding of a suspect food. The first or second exposure to one of the above foods should provide a clue to the diagnosis. Some infants, on the other hand, will tolerate their infant formula in the early months, then begin to react to it. Previously healthy breastfed infants may suddenly react when mom eats one of these foods, then breastfeeds the baby.
The vomiting is unusually intense. GERD usually involves milder regurgitation or, at the most, one or two vomits right after a feed, then the infant appears well. With FPIES, vomiting persists several times each hour for a few hours, often followed by diarrhea. This pattern is somewhat indistinguishable from a stomach flu or food poisoning at first; repeated episodes that become increasingly worse tell the tale.
Lethargy and shock. Some infants, as described above, will experience a shock-like state from a drop in blood pressure. Repeated episodes that result in such emergencies should provide a clear clue to the diagnosis.
Emergency Care
Infants who are extremely pale or lethargic should receive emergency care. Intravenous fluids are usually needed, and, rarely, epinephrine may be given to assist in the resuscitation of severe cases. Blood tests will likely be done to assess hydration status and check for infectious causes. Steroids may be useful in shortening the reaction, but are rarely needed.
Fortunately, most infants don’t progress this far into the reaction; vomiting persists for several hours, then resolves, and the infant recovers without any lasting effects.
Diagnostic Oral Food Challenge
Some experts advise that infants receive a test feeding of the reactive food in a controlled environment, such as an allergist’s office, in order to observe the reaction and confirm the diagnosis. This is unnecessary if the infant’s history is already obvious for FPIES. It may be useful if the diagnosis is in doubt.
Treating FPIES
The only known treatment at this time is avoidance of the reactive food. Most infants will only react to one or two foods, though some will react to the whole list. Breastfeeding moms will need to keep reactive foods out of the diet, and infants who react to a milk or soy based formula may need to use a hypoallergenic one. You can decide whether to keep all FPIES foods out of your infant’s diet, even those you haven’t started yet, or to simply avoid the foods that cause a definite reaction.
Fortunately, children outgrow FPIES sensitivity by three or four years of age.