Adverse Food Reactions and Allergies

Adverse Food Reactions

• Adverse food reactions can be the result of food hypersensitivity or food intolerance.
• Food hypersensitivity is an adverse immunologic response, while food intolerance is an adverse physiologic response.
• Examples of food intolerance include lactose intolerance, glucose 6 phosphate dehydrogenase deficiency, and galactosemia.
• Fava beans can cause a deficiency in NADPH, which can lead to oxidative stress and red blood cell lysis.
• The definition of food allergy is a specific immune response that occurs reproducibly upon exposure to a given food.

Food Allergy

• Food allergy occurs when the immune system reacts to a substance (allergens) that is usually harmless.
• The immune system mistakenly assumes the allergen is harmful and creates an immune response.
• Sensitization is exposure to an allergen, which can lead to hypersensitivity.
• Young infants are susceptible to food allergies due to their immunological immaturity and immature gastrointestinal tract.
• Infants lack IgA and IgM in exocrine secretions, and salivary secretory IgA is absent at birth.
• IgE-mediated mechanisms are the most well-characterized form of hypersensitivity response, often occurring immediately or within 2 hours.
• IgE attaches to a mast cell, causing the release of chemical mediators like histamine, serotonin, and kinins.
• Anaphylaxis is a rapid-onset, life-threatening allergic reaction.
• Food allergy is the #1 cause of anaphylaxis in emergency departments.
• Common foods implicated in anaphylaxis are peanuts, tree nuts, seafood, cow's milk, and eggs.
• Oral Immunotherapy, also known as oral desensitization, can promote tolerance to allergens by gradually introducing small amounts of the allergen.

Oral Allergy Syndrome/Pollen Food Syndrome

• Oral allergy syndrome is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts.
• The immune system recognizes pollen and similar proteins in food, causing an allergic response.
• Unlike simple food allergy, OAS requires prior sensitization to a cross-reacting inhalant allergen.
• OAS manifests most commonly with pruritus (itching) of the lips, tongue, and mouth.

LEAP (Learning Early About Peanut Allergy) Study

• The LEAP study transformed the guidance on introducing peanut foods to children at high risk for food allergies.
• The study recommended introducing peanut foods between 4 - 6 months of age.
• Early consumption of peanut resulted in a 70-80% relative risk reduction of peanut allergy.
• The potential for preventing other food allergies through early life exposure is not as clear.

Food Allergy Management

• Registered dietitians play a critical role in food allergy management.
• The role of the dietitian includes providing education on food avoidance, suggesting alternatives, providing recipes and meal plans, evaluating compliance, and ensuring adequacy and enjoyment of the diet.
• While peanut and tree nut allergies are often considered permanent, studies show that some children can develop tolerance by school age.
• Food challenges are used to test for food allergies after resolution of symptoms.
• Food challenges typically start with a small amount of the food and gradually increase.
• Most reactions occur within 2 hours; however, non-IgE reactions may take longer.
• Infants under 2 years experiencing mild reactions may be rechallenged every 4-6 months to check for continued symptoms.
• Older patients may be rechallenged every 1-2 years depending on the difficulty of avoiding the food in question.
• Sensitivity to certain types of food antigens, such as peanuts, tree nuts, and seafood, can be lifelong; rechallenging should be done no sooner than every 5 years.
• Restricted diets for conditions like celiac disease or dermatitis should be continued indefinitely.
• Most children are only allergic to one to two foods.

Breastfeeding and Food Allergies

• Babies at high risk for peanut allergy should be introduced to peanut as early as 4-6 months of age.
• All babies should be introduced to peanut in their first year of life, regardless of allergy risk.
• There is no conclusive evidence that breastfeeding alone can prevent food allergies, but it may help prevent eczema.