Nutrition for Life - 2017

Food Allergies & Intolerances

By Parul Kharod

Millions of people suffer from some sort of food sensitivity. Food allergies and intolerances are on the rise in both adults and children. Some blame it on genetically modified crops or pesticides in the soil or hormones and preservatives in processed foods. Recent research also suggests a link between inflammation and food sensitivities.

The exact causes of food sensitivities are not certain. Some scientists believe that some people are genetically predisposed and more likely to develop an allergy or intolerance to certain proteins, ingredients or additives in foods if there is a family history.

Most adverse reactions to foods can be divided into two categories:

1. Allergy
2. Intolerance

What is a food allergy?

An allergic reaction happens when the immune system reacts to a particular food protein or allergen. This reaction can happen within seconds of ingesting the allergen or take up to several hours to occur. A sudden, severe, life-threatening reaction known as anaphylaxis may result. A tiny amount of an allergen is often enough to trigger a reaction. It is important to remember that the symptoms are caused by the allergic person's unique immune response to the food, not the food itself.

Food Allergies can be divided based on the type of immune response:

• IgE
• Non-IgE
• Mixed Response

Immunoglobulin E (IgE) are antibodies produced by the immune system.

When your immune system overreacts to an allergen, it produces antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals, causing an allergic reaction and various symptoms.

Each type of IgE has specific “radar" for each type of allergen. Some people are only allergic to cat dander as they only have the IgE antibodies specific to cat dander; while others have allergic reactions to multiple allergens because they have many more types of IgE antibodies.

IgE reactions are one of the most common types of food allergies. Eight foods account for 90% of all food allergy reactions.

• Milk (casein, whey)
• Eggs
• Wheat (gluten)
• Soy
• Peanuts
• Tree nuts
• Fish & Shellfish

People who are allergic to latex or have seasonal allergies to grass or birch pollen may also experience allergies to certain fruits and vegetables that mimic similar immune response.

Non-IgE mediated allergies are believed to be generally T-cell-mediated. They include Food Protein Induced Enterocolitis Syndrome (FPIES) and Food Protein Induced Allergic Proctocolitis (FPIAP) which are types of food allergies affecting the gastrointestinal (GI) tract.

Eosinophillic Esophagitis and Eosinophillic Gastroenteritis are Mixed Response reactions as they may have a combination of immune triggers.

Celiac Disease is not really a food allergy but an autoimmune disorder in which gluten (a protein found in wheat, rye, and barley) triggers an immune response that damages the inner lining of the small intestine.

Key components of food allergy:

• An immunologic response to a food protein
• Exquisitely small amounts may cause a reaction
• Reactions can be severe and even life-threatening

A food allergy can be diagnosed by a skin-prick test or blood testing. However, these tests are not 100% accurate as they may have false positives. The correct interpretation of these tests is extremely important.

What is food intolerance?

Food intolerance does not involve the immune system. It is a physical reaction to a specific food or food substance. Responses are often delayed and may take several hours or even days to appear. Multiple reactions may occur, from headache to bloating, diarrhea, skin problems and a general feeling of illness.

Food intolerance can be caused by many different factors including natural or artificial chemicals in foods and how the body processes a food or food substance.

Intolerances can be divided into three categories:

• Metabolic
• Pharmacologic
• Undefined/Mixed

Metabolic Intolerances are due to some physiological factors:

• Enzyme Deficiencies
• Lactose Intolerance
• Sucrose Intolerance
• Absorption Abnormalities
• Fructose Malabsorption

Pharmalogical Intolerances are related to sensitivities to certain chemical compounds naturally present in foods such as histamines.

Mixed responses include reactions to Sulphites, MSG, food coloring, and other such chemicals.

Food intolerances are difficult to diagnose, because there are not many validated tests available. Enzyme deficiencies can be tested by a blood test. Fructose malabsorption can be tested by a breath test that measures the gases hydrogen and methane. One type of testing, known as mediator release testing, claims to measure changes in white blood cells in response to inflammation, after an antigen challenge, but the test is considered controversial, and its use has not been validated. There are other tests such as the Lifestyle Eating and Performance (LEAP) protocol which may help patients to not only identify food sensitivities, but more importantly, to identify their least reactive foods.

Nutrition Tips and Advice

• Do not self-diagnose and eliminate foods without professional guidance
• Wash hands before and after eating to avoid the transfer of food allergens
• Know all the different ways that manufacturers can label foods
• Read all ingredients, warnings, and fine print
• Read the label every time you buy a product as ingredients can change any time
• Be aware of the food labeling discrepancies: for example, dairy-free is not the same as milk free
• Avoid bulk foods
• Avoid the deli counter
• Don't hesitate to ask for change of gloves, use of fresh utensils, etc.
• Have an emergency kit easily accessible that includes your medications, auto-injector (Epi-pen) and care plan.
• Limit packaged and processed foods
• Choose naturally allergen free real foods
• Make sure to eat a balanced diet while eliminating allergen foods
• Consult a Registered Dietitian to make sure you are eating a balanced diet.


Food Allergy Research & Education (FARE)
American Academy of Allergy, Asthma and Immunology
National Institute of Allergy and Infectious Disease
Food Allergen Labeling and Consumer Protection Act (FALCPA)
Kids with Food Allergies Foundation
Celiac Disease Foundation

-- Parul Kharod, MS, RD, LDN is a registered dietitian and licensed nutritionist and works as a Clinical Dietitian with Outpatient Nutrition Services at WakeMed Hospital in Cary and Raleigh. She can be reached at