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Food Allergy vs Food Intolerance: What's Causing A Reaction

An image of a boy refusing a bowl of peanutsFood allergy, food sensitivity, and food intolerance are all a form of reaction to ingested food, but their causes differ, and so should how you address them. These conditions may have symptoms that mirror each other, so they are often mistaken for each other. It’s important to be able to tell them apart in order to make the right choices about food-related issues. Here's how to spot the difference between food allergy vs food intolerance.

What's The Difference: Food Allergy vs Food Intolerance

What Is A Food Allergy?

A food allergy occurs when your body triggers an abnormal immune response to certain foods that are ingested. The body goes into protective mode against the perceived threat when this happens.

A food allergy is caused by allergens, or proteins, that travel through the body. They can accumulate in different areas, such as the throat, GI tract, or skin, where they cause symptoms.

In some food allergies, your immune system recognizes these allergens as invaders and releases immunoglobulin E (IgE), protein antibodies. The next time you eat that food, your mast cells, part of your immune system, are triggered by the presence of IgE to release histamine, causing an allergic reaction and familiar symptoms like sneezing or hives.

Other allergies are not mediated by IgE, and these allergies can take longer to manifest, although they still involve an abnormal immune response to food and the release of histamine. Scientists are still working to identify the primary mediating factors in these cases. Likewise, there are not good laboratory tests for these other types of allergies, meaning that a food elimination challenge may be the best method to identify them.

An allergic response can occur within a few minutes, a few hours, or a few days, regardless of the amount of the trigger food ingested. In the case of IgE-mediated allergies, a severe response could mean a life-threatening reaction - anaphylaxis - in which the airways tighten and blood pressure can drop quickly.

Types of Allergies

Food allergies are generally categorized into three types. These are:

  • Immunoglobulin E (IgE) mediated type of food allergy is one that causes the immune system to make IgE antibodies that recognize particular foods as a threat and react to fight the threat. Furthermore, this IgE allergic reaction typically develops within a few minutes of ingesting the food allergen. The reaction can manifest as mild or more severe symptoms, including anaphylaxis. This type of allergy can be identified with a skin prick test at a doctor's office.
  • Non-IgE-mediated food allergy involves other cells in the immune system that cause allergic reactions to the perceived threat. This is usually difficult to identify because symptoms can take up to several hours to emerge.
  • Mixed IgE food allergy involves some individuals experiencing symptoms of both types. Symptoms can manifest a few days after ingesting the food allergen. This type is also difficult to identify in a clinical setting.

What Is A Food Intolerance?

An image of a woman holding her stomach as she sits next to a glass of milkWhen food intolerance occurs, your digestive system experiences difficulty digesting or breaking down a particular food. A food intolerance typically affects only the digestive system, for example, lactose intolerance or gluten intolerance. The immune system is not responsible for food intolerance. Individuals with food intolerances tend not to make an adequate amount of a specific enzyme needed by the digestive system to fully break down a certain food or food ingredient.

Also, with some food intolerances, you may still be able to eat small quantities of the offending food without any reaction. Someone with certain gastrointestinal conditions may be more susceptible to food intolerance. And while food intolerance tends to be a life-long issue, it is not acutely life-threatening.

What Is A Food Sensitivity?

In some scientific circles, it's believed that food sensitivity is a reaction to the ingestion of a particular food that may be linked to increased levels of certain IgG antibodies and not IgE antibodies. While IgG is a normal part of how the body responds to food antigens, this response may be more dramatic in some people.

Food sensitivity symptoms can be immediate or delayed for several days after ingesting the trigger food. They may be unpleasant, but are not typically urgent or require emergency care. Common symptoms include fatigue, brain fog, sneezing, runny nose, bloating, diarrhea, and migraines. It's possible for a person to have food sensitivities but go years without an awareness of it because of the delayed reaction times and often vague symptoms that mimic common ailments.

Symptoms of Food Allergy vs Food Intolerance

Regarding the symptoms of food allergy vs food intolerance, the two can be easily confused and one is mistaken for the other. However, there are also some differences.

Depending on the type of food allergy, symptoms can occur between a few minutes following exposure to a couple of days. Some of the symptoms of food allergy include:

  • Swelling of the eyes, face, throat, and tongue
  • Difficulty breathing, including wheezing and asthma
  • Hives
  • Skin rash
  • Low blood pressure
  • Diarrhea
  • Vomiting and nausea
  • Itchy rash
  • Burning, itching, and swelling around the mouth
  • Runny nose
  • Abdominal cramps

Severe cases of food allergies can cause anaphylaxis, which could be fatal. This reaction needs urgent medical attention. Potentially life-threatening symptoms associated with anaphylaxis may include:

  • Breathing that is difficult or noisy
  • Swelling of the tongue
  • Throat swelling or tightness
  • Difficulty speaking
  • Hoarse voice
  • Coughing persistently
  • Wheezing
  • Dizziness
  • Fainting or collapse
  • Paleness and floppiness (in young children)
  • Irritability
  • Fatigue
  • Convulsions

Those with severe allergies should carry an epipen, or epinephrine autoinjector, to help arrest this kind of reaction.

Food Intolerance Symptoms

The symptoms of food intolerance aren’t life-threatening. Symptoms can appear within a few hours following ingestion of a trigger food and travel through the digestive tract. Some common symptoms to look out for include:

  • Abdominal pain
  • Diarrhea
  • Bloating and gas
  • Headaches or migraines
  • Heartburn or reflux
  • Nausea
  • Sweating
  • Palpitations
  • Nervousness
  • Upset stomach
  • Rashes
  • Fatigue
  • Runny nose
  • Flushed skin

Types: Food Allergy vs Food Intolerance

Comparing food allergy vs food intolerance, you find different types of allergens and offending intolerances.

Common Food Allergens

An image of common food allergensRoughly 90% of food allergic reactions are related to eggs, fish, peanuts, tree nuts, milk, wheat, and shellfish.

  • Peanut allergy is perhaps the most common allergy in older kids, with just about one in four outgrowing the allergy.
  • Cow’s milk allergy is common in babies and young children, but roughly 90% of kids will outgrow the condition before reaching four years old. While a cow’s milk allergy can occur in both IgE and non-IgE forms, the IgE form is the most common and has the potential to be the most concerning.
  • Egg allergy tends to affect more children than adults. However, 68% of children with an egg allergy outgrow it by the time they hit sixteen years old.
  • Tree nut allergy occurs when you develop a reaction to nuts (almonds, walnuts, pecans, macadamia nuts, etc.) and seeds from trees.
  • Shellfish and fish allergies could potentially lead to a severe and potentially fatal allergic reaction- anaphylaxis. However, a fish or shellfish allergy is sometimes mistaken for a reaction to a fish contaminant, like mercury or bacteria.
  • Wheat allergy tends to primarily affect children, but they tend to outgrow it around ten years old.

Other food allergens can include, soy, linseed, garlic, sesame seed, peach, avocado, kiwi fruit, celery, passion fruit, mustard seeds, and aniseed.

Common Food Intolerances

There are several common types of food intolerances. These include:

  • Lactose intolerance: You are lactose intolerant if you lack sufficient lactase enzymes to break down lactose (sugar in milk). When this occurs, it's difficult for the body to absorb the lactose through the intestine.
  • Fructose intolerance: The body experiences fructose malabsorption when this occurs because it lacks the protein to absorb the sugar (from fruit, vegetables, etc.) from the intestine.
  • Gluten intolerance: Gluten is a protein that’s found in some grains, like wheat, barley, and rye. An individual with gluten intolerance may experience both digestive and non-digestive symptoms. Furthermore, symptoms of gluten intolerance may sometimes be mistaken for Celiac disease (an autoimmune system response to gluten) or wheat allergy (an allergic response to wheat).
  • Salicylate intolerance: Salicylates are naturally occurring chemicals made in plants and found in vegetables, fruits, spices, and herbs. Also, artificial flavorings and preservatives contain salicylates. These are usually found in products like candies, chewing gum, and toothpaste.
  • Other known triggers of food intolerance include: Histamines, caffeine, amines, FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols), sulfites, aspartame, eggs, MSG (monosodium glutamate), food colorings, yeast, and sugar alcohols.

Sensitivity and Adrenal Fatigue Syndrome (AFS)

Where food sensitivities can be caused or worsened by a condition known as adrenal fatigue syndrome, which is caused by chronic stress. It results in the overuse of the NeuroEndoMetabolic (NEM) stress response, which causes cortisol levels to spike. This activates the Inflammation circuit, consisting of the microbiome, the immune system, and the GI tract. An overactive immune system can cause or worsen reactions to foods and other substances. Likewise, bacterial imbalances in the gut can lead to leaky gut, releasing food protiens into the body that can then be identified as threats by the immune system.

Fatigue and new food sensitivities are strong indicators of adrenal fatigue, and the slow onset of these symptoms is common for those experiencing the condition. Delayed food sensitivity, which is linked to adrenal sensitivity, causes particular bodily systems and functions to slow down. Food sensitivity symptoms can worsen when adrenal issues arise, like increased inflammation. Healing your adrenals, which can take some time, can help to reduce food sensitivities. So too can avoiding trigger foods like wheat or gluten.

Testing: Food Allergy vs Food Intolerance

It can be very difficult to identify whether a problem is due to a food allergy vs food intolerance. There are a number of tests that your doctor may order to check for a food allergy or an intolerance. Some of the best ones can be done at home yourself, but they do take discipline.

Tests Performed By A Doctor

An image of someone getting skin prick testing

  • Skin prick testing: This test is also called a puncture or scratch test. It involves a small quantity of food “pricked” into the skin with the use of a tiny needle. Often several of these pricks are done at once with the use of a special pad that is placed on the skin. You are exposed to the allergen. Then, the skin is monitored for around 20-30 minutes for signs of a reaction. This test works best for IgE allergies.
  • Blood tests: A blood test typically involves checking your level of IgE antibodies. Afterward, the measurement is used by your doctor to advise you on how to manage your food allergy.
  • Oral food challenges: This controlled feeding test is done under medical supervision and involves you eating the problem food slowly and gradually increasing the amount. After that, your doctor will confirm if you have a true food allergy or not.
  • Double-blind test: For this test, you eat food, but neither you nor your doctor knows which contains the allergen. This type of test is typically used when your doctor thinks that your reaction is not linked to a particular food. As such, the evidence from a double-blind test can be used to find the real cause of your reaction.
  • Hydrogen breath test: This test is specifically for detecting lactose intolerance. Firstly, you give your first breath sample. Then you drink a liquid that contains lactose. Afterward, you breathe into a breathalyzer machine every 15-30 minutes for a couple of hours. If you’re lactose intolerant, your test results will show high levels of hydrogen. This indicates that the lactose was undigested in your intestines.

At Home Tests

  • Blood Spot Tests: A blood spot test can typically check for IgG and IgA antibodies to foods, which is geared more towards food sensitivities rather than food allergies. These results can sometimes change year to year depending on the foods that you eat at that time also and can be useful to help reduce inflammation if staying away from the foods that come back positive for a certain amount of time.
  • Food diary: A food diary entails keeping a detailed record of all the foods you have eaten, specifically, and making a note of the timing and symptoms that emerge. This will help you to keep track of the foods you eat and any symptoms that develop after eating these foods. This may be necessary for several weeks to identify the connection between foods and symptoms.
  • Trial elimination test: For this test, you eliminate suspected problem foods from your diet for a period of time. This could be for 8 to 12 weeks weeks. You observe if the symptoms improve. Then, the foods are reintroduced slowly, one at a time, to see if the symptoms return. This type of test is considered the gold standard in checking for allergies, intolerances, and sensitivities. You should also be aware that it may only be when you eat over a certain amount of food that you get a reaction, so test both lower and higher quantities of that food.

How to Manage Food Allergies and Intolerances

Managing Food Allergies

There is no cure for food allergies. In the world of food allergy vs. food intolerance, food allergies can be managed with strict avoidance of the foods that trigger an allergic reaction. The severity of your food allergy will help your doctor or allergist determine if you may need certain medications, like epinephrine auto-injectors. Some medications that a doctor may recommend include:

  • Epinephrine: Helps to reverse symptoms of anaphylaxis in an emergency
  • Antihistamines: Helps to minimize itching and congestion
  • Corticosteroids: Helps reduce swelling

An image of someone talking with their doctorConsult with a doctor or allergist if you suspect that you have a food allergy. Identifying and avoiding the allergen is often the best course of action.

You can also pay attention to food labels and product ingredients to avoid exposure to certain hidden allergens, like nuts, eggs, and sulfites. You may need to look up other names a food you are allergic to can appear as, as many foods are hidden in food labels. It’s a good idea to consult with a registered dietitian who can help you to maintain a nutrient-rich balanced diet, while safely avoiding foods that can trigger an allergic reaction.

Managing Food Intolerances and Sensitivities

If you are dealing with food intolerance, you may have to change your diet by reducing or eliminating foods your body does not tolerate. You may be able to limit symptoms by consuming small amounts of a problem food rather than eliminating it. Your doctor may recommend over-the-counter medicines, such as antacids or antidiarrheals (e.g. Imodium, Pepto-Bismol) to help manage some symptoms.

Lactose-free milk and other dairy products are available as an option for individuals who are lactose intolerant. Also, lactase enzyme, which helps to break down the lactose, can be found over-the-counter in the form of pills or drops. You can ingest a pill before consuming dairy products or add lactase drops directly to your milk products.

Restoring balance to the Inflammation circuit can also help to reduce the severity of food sensitivities. Taking Omega 3 or bromelain supplements, probiotics, and drinking lots of water may help, along with taking steps to reduce inflammation and improve gut health. If you experience adrenal fatigue, this could mean careful management of the ailment.

It's very important to heal the gut if you have food sensitivities as it could worsen in the future down the line to worse consequences like autoimmune disease or chronic fatigue or inflammation in the gut.

When to Call For Help

Call your doctor if you have an allergic food reaction and you experience a loss of consciousness, swelling of the lips, mouth, throat, or tongue,  or trouble breathing. Also, get emergency care if you suffer an asthma attack after eating, or after an epinephrine shot, even if you feel better.

If you have a food intolerance issue, call your doctor if you experience extreme diarrhea or abdominal pain, a severe food reaction, or weight loss that's puzzling.

The Takeaway

Whether it's a food allergy, food intolerance, or food sensitivity, it can compromise your overall health and well-being. However, knowing what food is the problem is often the key to managing the symptoms. If you suspect you have an allergy or intolerance to a food, try going on a food elimination diet and keeping a food diary. Then, schedule an appointment with an allergist to get tested. Often, knowing which foods trigger your symptoms is key to keeping them under control.

If you are concerned you have a food sensitivity or allergy, but aren't sure which, the team at Dr. Lam Coaching can help. We offer a free** no-obligation phone consultation at +1 (626) 571-1234 where we will privately discuss your symptoms and various options. You can also send us a question through our Ask The Doctor system by clicking here.

© Copyright 2023 Michael Lam, M.D. All Rights Reserved.

Dr. Lam’s Key Question

When it comes to a food allergy vs food intolerance, a food allergy occurs when your body triggers an abnormal immune response to certain foods that are ingested. On the other hand, a food intolerance occurs when your digestive system experiences difficulty digesting or breaking down a particular food because of the absence of a specific enzyme. Allergies can be a life-threatening emergency, while intolerances are generally not.

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