Over 50 million people in the U.S. experience various types of allergies each year (including environmental, food, drug, insect, latex allergies, and more). In fact, allergies are the sixth leading cause of chronic illness in the U.S.

Plus, food allergies, intolerances, and sensitivities are on the rise and can be difficult to identify when the symptoms are not always immediate or severe. They can nevertheless negatively impact health—so here’s a look at the different types of reactions.

Allergy Definition

An allergy is a “damaging immune response by the body to a substance, especially pollen, fur, a particular food, or dust, to which it has become hypersensitive.” (Oxford Dictionary) Allergies are an immune reaction to a food that begins immediately after it is eaten and may involve mild to severe food allergy symptoms such as runny nose, hives, vomiting, wheezing, or difficulty breathing.

The top eight allergens include milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish. Interestingly, sesame allergies are also on the rise (declared a major allergen in 2021) with an estimated 1 million allergic persons in the US.

About 32 million Americans have food allergies, which is roughly 10.8% of US adults and 7.6% of US children.

Balancing Act With the Immune System

Our immune systems protect our bodies from outside “invaders” but, sometimes, the immune system can identify something like food as dangerous and “overreact” in an attempt to offer protection.

There are four types of hypersensitivity reactions that can be helpful to understand.

Type 1: A hypersensitivity (IgE) reaction is almost immediate and occurs when the body is exposed to an allergen and releases histamine and other chemicals that cause swelling and inflammation (e.g., food allergies, allergic asthma, skin allergies, allergic rhinitis, environmental allergies, and animal/insect allergies).

Type 2: A cytotoxic (IgM, IgG) reaction occurs when antigens bind with antibodies on the surface of a cell, leading to cell death (e.g., autoimmune reactions like Graves Disease and certain medication reactions).

Type 3: An immunocomplex (IgG) reaction occurs when antigens bind with antibodies, and then settle onto the surface of blood vessels, tissues, joints, or organs; when the body responds to their presence, it causes tissue damage (e.g., lupus or rheumatoid arthritis).

Type 4: This reaction involves white blood cells (instead of antibodies) and is unique because it takes longer for the body to react. Symptoms appear at least 24 hours or more (often 48-72 hours) after exposure (e.g., poison ivy or contact dermatitis).

Intolerance and Sensitivity

Organizations such as the American Academy of Allergy, Asthma, and Immunology group food intolerances and sensitivities together in their definition, saying food intolerance or food sensitivity “occurs when a person has difficulty digesting a particular food. This can lead to symptoms such as intestinal gas, abdominal pain, or diarrhea.”

It is helpful to further distinguish the difference between intolerance and sensitivity. The Institute for Functional Medicine defines food intolerance as a reaction to components of food (histamine, lactose, and so forth) that a person’s body is unable to break down due to lack of an enzyme or other nutrient. This can lead to symptoms such as flushing, inflammation, or cold/flu-like symptoms. This is different from an allergy and sensitivity because it is not due to how the immune system is responding.

Food sensitivities may be more confusing to identify as they may occur hours to days after eating a food to which one is sensitive. These sensitivities are often caused by an imbalance in the digestive system that in turn affects the immune system. Common foods related to sensitivities include dairy (cow’s milk), soy, eggs, gluten, tree nuts, and other ingredients such as gums and thickeners.

The list of symptoms for sensitivities is much more extensive, including but not limited to migraines, headaches, dizziness, trouble sleeping, mood swings, depression, anxiety, weight changes, dark circles under the eyes, asthma, irregular heartbeat, bloating, wheezing, runny nose, sinus problems, ear infections, food cravings, joint or muscle pain, indigestion, nausea, vomiting, bladder control issues, fatigue, hyperactivity, hives, rashes, dry skin, excessive sweating, and acne.

Why is Reducing Chronic Inflammation Important?

Continued exposure to foods that are causing an allergy, intolerance, or sensitivity can cause chronic inflammation, which is known to contribute to chronic conditions such as heart disease, diabetes, cancer, Alzheimer’s disease, and many others.

Complete elimination of foods that do not cause a severe reaction (i.e., anaphylaxis) along with careful reintroduction is considered the “gold standard” for identifying non-severe allergies, sensitivities, and intolerances (and is less costly than food allergy testing).

Please note that elimination plans are never appropriate if you have a severe allergy. We always recommend working closely with a skilled practitioner to safely and accurately identify food allergies.

Often it is recommended to start with the top eight allergens along with alcohol and caffeine— avoiding them for three to four weeks (while focusing on whole unprocessed foods that do not contain preservatives, gums, thickeners, colors, and so forth). Then carefully reintroduce each category that you’ve eliminated, one at a time, each over three to five days. Carefully note any symptoms that occur (even if they are subtle like runny nose, brain fog, fatigue, or something similar).

Starting with all of the top allergens at once can be overwhelming, so it may be easier to start with foods that are “suspect.” These are the foods that you’ve already noticed cause some type of reaction (such as dairy products causing gas or bloating).

For most people, at the end of the three-week elimination period, they will notice that inflammation in their body has been greatly reduced and they are feeling more energetic, in tune with their body, and able to more clearly identify any symptoms that may occur.

The goal is to be able to enjoy as much variety and diversity of whole foods as possible. If a food is identified as causing symptoms in the body, then continued avoidance of that food is advised while you work with your practitioner to optimize digestion, heal the gut, and balance the immune system.

Applying Mindful Eating to Tune Into the Body

Taking time to breathe, feeling grateful, being present, and sitting down to eat can not only improve digestion and satisfaction but can also help you to tune into how your body is feeling before and after eating. Often we are distracted by business, tolerating symptoms because we have become used to them, or intentionally not listening to the signals our body is sending us. That doesn’t mean that our body stops communicating but, instead, the signals (or symptoms) get louder and louder and, eventually, are unable to be ignored (in the case of many diseases).

Here’s more about mindful eating:

How Do Farming Practices Relate to Food Allergy, Intolerance, and Sensitivity?

Sesame is an example of a rising food allergen that may cause you to pause and ask why more people are developing allergies. On the surface, the most common answer is that more people are consuming sesame and, thus, more people are becoming allergic to it (think tahini and burger buns, and sesame oil is the sixth most common seed oil).

Sesame is a resilient plant, tolerating poor soil and dry growing conditions but, unfortunately, is often intercropped with GMO cotton that is heavily sprayed with herbicides and pesticides. One common pesticide used is metolachlor. The EPA says that “human health effects from metolachlor at low environmental doses or at biomonitored levels from low environmental exposures are unknown (U.S. EPA, 1995).”

The Hazardous Substance Fact Sheet on metolachlor does point out that repeated exposures may cause an allergic reaction, which raises this question: is it the sesame or how the sesame is being grown? We don’t have the answer yet as it requires more research, but it’s worth investigating as food allergies continue to rise.

Another more commonly discussed allergen is wheat with a skyrocketing number of people unable to tolerate gluten. Changes in plant breeding and agricultural practices, such as the application of glyphosate to help dry wheat prior to harvest, have likely contributed to this growing intolerance.

So, it’s important to not only consider the impacts of the direct ingestion of fungicides, pesticides, and herbicides on human health (and the health of the microbes in our gut) but also the effects they have on the health of the soil, the plant, and the planet.

Histamine Intolerance

Histidine is an essential amino acid for plant growth and development and is essential for our bodies to make protein. Histidine is converted in the stomach, mast cells (immune system), and in certain regions of the brain to histamine. Histamine is also produced by certain bacteria, yeasts, and molds that may increase the likelihood of histamine intolerance if those specific strains overpopulate the digestive tract.

Histamine plays many important roles in the body. It stimulates stomach acid secretion, plays a role in inflammation and dilation of blood vessels (swelling), affects muscle contractions in the intestines and lungs, affects wakefulness, and affects heart rate.

Tomatoes are one of many vegetables that naturally contain histamine with the substance involved in making two of the volatile flavor molecules in tomatoes. Others with histamine include spinach, eggplant, and fermented foods—with plenty of others having varying levels of histamine as well. The ripeness of vegetables like tomatoes influences the histamine content (i.e., a green tomato contains less histamine than a red tomato).

Wine is another source of histamine (if your face flushes when you drink, this is histamine). If trying to minimize histamine, consider avoiding wine or switching to white wine as it contains approximately half the amount of histamine as red.

For most people, if your body is clearing histamine quickly and efficiently enough (meaning that you have plenty of the enzyme diamine oxidase (DAO) in the digestive tract), then eating foods that contain histamine will not cause a reaction. However, due to a number of potential causes, if DAO is low, histamine will not be broken down properly and may cause symptoms such as gas, bloating, nausea, diarrhea, vomiting, runny nose, sneezing, changes in blood pressure, abnormal heart rate, headache, migraine, dizziness, hives, redness, itching, and menstrual pain and cramping.

Working with your healthcare practitioner to develop a plan that includes choosing lower histamine foods and working to increase how quickly your body clears histamine may be beneficial steps toward addressing histamine intolerance.

Speaking Up and Including Anti-inflammatory Foods

Healing from food allergies, sensitivities, and intolerances can take time and plenty of trial and error. Eating out and going to parties and other gatherings can be incredibly difficult with food allergies, sensitivities, and intolerances, and can take a significant social and emotional toll. Know that you are not alone and it is okay to speak up about your dietary needs.

Including a diverse mix of whole foods rich in nutrients helps to nourish the body and provides plenty of colorful phytochemicals that reduce inflammation. Focusing on the abundance and diversity that is available to you (versus what you are avoiding) is a mindset shift that you may find helpful.


American Gastroenterological Association. Food allergies and intolerances: food allergy vs. food intolerance. https://aga-cms-


American Academy of Allergy, Asthma & Immunology. Food intolerance versus a food allergy. https://www.aaaai.org/conditions-


Biogenic Amines Formation, Toxicity, Regulation in Food: https://pubs.rsc.org/en/content/chapterhtml/2019/bk9781788014366-00001?isbn=978-1-78801-436-6

Histamine Intolerance Originates in the Gut: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069563/

Histamine Intolerance—The More We Know the Less We Know. A Review: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8308327/

Low-Histamine Diets: Is the Exclusion of Foods Justified by Their Histamine Content? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143338/

Metolachlor Hazardous Substance Fact Sheet: https://nj.gov/health/eoh/rtkweb/documents/fs/3374.pdf

Real Food Encyclopedia Sesame: https://foodprint.org/real-food/sesame/

U.S. Food and Drug Administration. Food allergies. https://www.fda.gov/food/food-labeling-nutrition/food-allergies.

Vojdani A, Vojdani C. Immune reactivities against gums. Altern Ther Health Med. 2015;21 Suppl 1:64-72. PMID: 25599187.