Food allergy series: Risk factors for developing food allergies
- Genetics is a factor in development of food allergies.
- Poor skin integrity makes food allergies more likely.
- Children with peanut or tree nut allergies usually react on the first ingestion.
- Household peanut exposure is a risk factor for peanut allergy in infants.
- Not clear if maternal diet while gestating can affect food allergies.
- Low vitamin A and low vitamin D are risk factors.
- Sun exposure and vitamin D deficiency may be connected to food allergies.
- Hygiene hypothesis posits that changes in hygiene and cleaning has caused immune changes that may lead to allergies.
- Gut microbiota also important in food allergies.
Food allergy series: FPIES (Part 1)
- FPIES is the most severe GI food hypersensitivity that is not IgE mediated.
- Thought to be caused by a delayed allergic pathway.
- Causes profuse, repetitive comiting, diarrhea, acute dehydration, lethargy and weight loss.
- Vomiting usually occurs 1-3 hours after eating offending food.
- Vomiting is seen in 100% of cases.
- Diarrhea is seen in 24% of cases.
- Can cause low blood pressure and hypothermia.
- Chronic symptoms can develop if food is not avoided.
- About 75% of patients look seriously ill.
- 15% have blood pressure low enough to require hospitalization.
- FPIES usually onsets between 1-3 months of age, but can be as late as 12 months.
- Symptoms usually occur 1-4 weeks after introducing cow’s milk or soy.
- About 30% later develop atopic conditions.
- 20% have family history of food allergies.
- 80% react to more than one food.
- Usually improve after beginning casein hydrolysate based formula.
Food allergy series: FPIES (part 2)
- FPIES is diagnosed clinically.
- Endoscopy and biopsy is often performed to rule out other conditions.
- GI tract of FPIES patients shows inflammatory changes, such as ulceration and bleeding.
- Baseline intestinal absorption is usually normal.
- Food specific IgE is not usually present.
- FPIES is managed with diet.
- Exclusive breastfeeding can be protective against FPIES.
- Oral food challenges require significant precautions and medical supervision.
- Challenges are recommended every 18-24 months in asymptomatic patients.
- 60% of FPIES cases resolve by three years of age.
- In the US, only 25% of cases resolve by three years of age.
- Most FPIES patients have some form of atopic disease.
- Some patients may change from an FPIES type reaction to an IgE allergy type reaction.
- Prevalence is different in different populations.
- Median age for resolution of FPIES depends on the food and ranges from 4-7 years of age.
- FPIES overwhelmingly affects very young children.
- In very rare cases, older children and adults develop FPIES to fish or shellfish.
Food allergy series: Eosinophilic gastrointestinal disease (Part 1)
- Eosinophilic gastrointestinal disease (EGID) is when eosinophils cause disease in the GI tract.
- Eosinophils are white blood cells with similar functions to mast cells.
- Eosinophils fight infections and participate in allergic response.
- Eosinophils can degranulate.
- Many GI conditions can elevate eosinophils in the GI tissue.
- No consensus on what is a high eosinophil count/hpf.
- Eosinophilic gastroenteritis can affect any part of the GI tract, but usually the stomach and small intestine.
- Eosinophilic gastroenteritis causes swelling of the Gi tract, eosinophils in the tissue and ulcerations.
- 50-70% of eosinophilic gastroenteritis is thought to be from allergic reactions.
- The reason for eosinophilic gastroenteritis is not clear.
- Eosinophilic esophagitis is 15 or more eosinophils/hpf in at least one field.
- Eosinophilic esophagitis can be allergic or not.
- Eosinophilic colitis is a rare condition with sudden onset colon inflammation with eosinophil infiltration that often spontaneously resolves.
- Eosinophilic enteritis is limited to the small intestine.
- Allergic proctocolitis affects rectum and/or colon of children under the age of 2.
- Allergic proctocolitis can be the result of food allergy, most often soy or cow’s milk.
Food allergy series: Eosinophilic gastrointestinal disease (Part 2)
- There are many conditions that can cause eosinophils to be increased in the GI tract.
- Allergy associated colitis is when eosinophils aggregate in the small and large intestines as the result of an allergic reaction.
- Hypereosinophilic syndrome is when people have too many eosinophils in the blood. Rarely, this causes eosinophils to become elevated in the colon.
- Crohn’s disease causes inflammation of the digestive tract. Eosinophils in the GI tract can be elevated due to inflammation.
- Ulcerative colitis causes inflammation of the colon. Eosinophils can be elevated in the colon due to inflammation.
- Collagenous colitis causes inflammation of the colon and rectum. Eosinophils can be elevated. It may occur due to drug reactions.
- Lymphocytic colitis causes inflammation of large portions of the colon. Eosinophils can be elevated in the mucosal layer.
- Autoimmune colitis is when autoimmune patients experience colon inflammation. Eosinophils and mast cells are usually found together in affected tissue.
- Graft versus host disease is a complication of a bone marrow transplant. Eosinophils can be elevated, including in the GI tract.
- Peripheral/intestinal T cell lymphoma is a cancer that usually affects the small intestine. Eosinophils infiltrate the affected tissue.
Food allergy series: Eosinophilic gastrointestinal disease (Part 3)
- 70% have family history of allergies
- 10% have immediate family member with EGID
- Can cause abdominal pain, GI dysmotility, vomiting, diarrhea, trouble swallowing, anemia, low blood protein and failure to thrive
- Can cause malabsorption
- EGID patients are very sensitive to foods. Eggs, milk and fish are most common problem foods.
- Elimination diets are mainstays of treatment
- Complete resolution often seen with elemental amino acid diet
- Reintroduction of foods is not usually tolerated
- Steroids effective but don’t produce lasting results
- Mast cells often increased in EGID biopsies
- Current treatment options not great
Food allergy series: Eosinophilic esophagitis (Part 1)
- EoE patients are three times more likely to be male than female
- Most patients have history of atopic disease
- Usually presents in childhood or after third decade of life
- Adults tend to have trouble swallowing, food impaction and upper abdominal pain
- Children have less specific symptoms, including vomiting, abdominal and chest pain
- 50-60% have at least one atopic condition
- 15-43% have IgE mediated food allergies, are at greater risk for food induced anaphylaxis
- No consensus on how many eosinophils/hpf is high
Food allergy series: Eosinophilic esophagitis (Part 2)
- Endoscopy with biopsy is only reliable diagnostic method
- May look normal by eye, so multiple biopsies should be taken
- Mast cells are increased in EoE more than in GERD
- Other tests rule like esophageal manometry, pH testing and barium swallows can help rule out other conditions
- Important to exclude GERD
- 40-50% EoE patients have increased in blood eosinophils
- When EoE is effectively treated, blood eosinophil count decreases
- Patients with EoE are found to have overexpression of several proteins
- Other genetic links have been found
Food allergy series: Mast cell food reactions and the low histamine diet
- Minimizes histamine in food consumed
- Histamine from outside sources can induce mast cell degranulation
- Common problem foods for mast cell patients, like alcohol, vinegar and aged cheeses, are high histamine and cause degranulation
- There are many different versions of this diet. I use this one.
- Avoid fermented foods, preservatives, dyes, leftovers, anything overly ripe, canned and pickled products
- Recommends strict adherence for four weeks to determine if it works
- Not all recipes labelled low histamine are low histamine
Food allergy series: Eosinophilic esophagitis (part 3)
- Treatment first rules out GERD or PPI responsive esophageal eosinophilia by treatment with PPIs for 8-12 weeks
- Some patients have primary EoE and secondary GERD
- Dietary management is the cornerstone of EoE treatment
- Dietary management is very effective in children, can achieve remission
- Food tolerance is unlikely to be achieved even with long erm elimination
- Steroids effective, but do not produce lasting benefits
- Fluticasone and oral viscous budesonide effective in studies
- Cromolyn has no clear benefit for EoE
- Leukotriene receptor antagonists like Singulair might help, not clear
- 11-55% of EoE patients suffer food impaction and require emergency intervention
- Esophageal rings are common in EoE patients
- Strictures larger than 1 cm in 11-31% of adults with EoE
- Esophageal perforation can occur and may require surgery
- Esophageal cancer and generalized EGID are not known to result from progression of EoE
- Esophageal dilation is sometimes to treat difficulty swallowing and impaction
Food allergy series: Eosinophilic colitis
- Can occur secondarily to many conditions, such as liver transplant and scleroderma
- Less than 100 cases of primary eosinophilic colitis reported in literature
- Experience lower GI symptoms, such as abdominal pain, constipation, diarrhea and rectal bleeding
- More severe cases can cause malabsorption, obstructions, free fluid in the abdomen in weight loss
- Symptoms often sudden onset, sudden resolve – relapsing/remitting
- Dense eosinophilic infiltration in colon
- Infiltration can occur in one large contiguous region or smaller isolated regions
- No true consensus on what constitutes above average eosinophil count in GI tract
- Sometimes have too many eosinophils in blood
- Patients often have elevated total IgE
- Treated with elimination diet, steroids, ketotifen and immunosuppressants