Food Sensitivity vs. Food Intolerance vs. Food Allergy

Understanding the differences in adverse food reactions

Sacramento, Calif. – There are many terms used to describe adverse food reactions, including food allergies, food sensitivities, and food intolerances. These terms are often used interchangeably by the general public and even by some clinicians, which can lead to confusion.

This confusion partly arises from the fact that food can trigger adverse reactions through various pathways in the body—such as IgE-mediated vs. non-IgE-mediated responses, or immunological vs. non-immunological mechanisms. The terms themselves, however, do not always clearly reflect these specific underlying mechanisms.

What is a Food Allergy?

In 2010, the National Institute of Allergy and Infectious Diseases (NIAID) developed clinical guidelines for the diagnosis and management of food allergies. They defined a food allergy as “an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food” [1].

The challenge with this definition is that it encompasses both IgE-mediated and some non-IgE-mediated immune responses. IgE-mediated food allergies (also known as Type I or immediate hypersensitivity reactions) are the most commonly recognized. These can lead to rapid-onset, potentially life-threatening reactions such as anaphylaxis, urticaria (hives), and angioedema, often triggered by foods like shellfish or nuts.

What is Food Intolerance?

Food intolerance refers to a non-immunological reaction to food, typically due to the absence or deficiency of a digestive enzyme. A classic example is lactose intolerance, where an individual is unable to digest lactose (a sugar found in milk) due to a deficiency in the enzyme lactase.

This type of reaction involves the digestive system, not the immune system [2]. Intolerance can also occur in response to certain food additives such as artificial dyes, monosodium glutamate (MSG), and preservatives.

What is Food Sensitivity?

Food sensitivities are non-IgE-mediated immune responses to food and may involve delayed hypersensitivity reactions. These are typically mediated by IgG antibodies, immune complexes, or cellular responses, and are classified into several types:

• Type I: Immediate reaction mediated by IgE antibodies (anaphylactic)
• Type II: Cytotoxic reaction mediated by IgG or IgM antibodies
• Type III: Immune complex-mediated reaction
• Type IV: Delayed reaction mediated by T-cell (cellular) responses [3]

Food sensitivities are the most prevalent of the three categories, affecting an estimated 30–40% of the population. They are complex in nature and frequently contribute to inflammation and a wide range of chronic health conditions, including IBS, IBD, depression, obesity, metabolic syndrome, GERD, migraines, fibromyalgia, arthritis, ADD/ADHD, and various skin disorders [4].

The difficulty in identifying food sensitivities stems from several factors:

• Symptoms may be delayed by several hours or even days after ingestion.
• Reactions can be dose-dependent, where small amounts may not elicit symptoms, but larger quantities can.
• Multiple immune and non-immune pathways may be involved.

Regardless of the pathway, a common hallmark of food and chemical sensitivities is the release of inflammatory mediators—such as cytokines, leukotrienes, and prostaglandins—from immune cells (including neutrophils, monocytes, eosinophils, and lymphocytes). These mediators are responsible for triggering inflammation in the body.

It is crucial to identify and temporarily eliminate food sensitivities to:

1. Alleviate symptoms,
2. Halt or reverse the progression of chronic disease, and
3. Allow the body time to heal—while simultaneously addressing the root causes of why the sensitivity developed in the first place.

There are many potential contributors to the development of food sensitivities, including:

• Overexposure to certain foods or food chemicals.
• Increased intestinal permeability (“leaky gut”),
• Gut dysbiosis,
• Past infections or food poisoning,
• Nutrient deficiencies,
• Weakened digestive enzyme function leading to incomplete digestion of food, and

If you would like to find out if you have food sensitivity, please consult a naturopathic doctor.

References

1. Guidelines for the Diagnosis and Management of Food Allergy in
   The United States. J Allergy Clin Immunol. 2010 December ; 126(6): 1105-1118. doi:10.1016/ j.jaci.2010.10.008.
2. Food Problems: Is it an Allergy or Intolerance. Cleveland Clinic.
   https:// my.clevelandclinic.org/health/diseases/10009-food-problems-is-it-an-allergy-or-intolerance
3. Marwa K, Kondamudi NP. Type IV Hypersensitivity reaction. [Updated 2021 Apr 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:
   https://www.ncbi.nlm.nih.gov/books/NBK562228/
4. Understanding Diet-Induced inflammation. Oxford Biomedical Technologies.
   https://www.nowleap.com/understanding-diet-induced-inflammation/

Explore additional topics from Sacramento Naturopathic Medical Center with Dr. Godby, ND, MA and his team at Natural Wellness.

As a naturopathic doctor for the last 20 years, I have witnessed the power of a preventative lifestyle and naturopathic medicine to transform the health and lives of thousands of patients.

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Sacramento, CA 95816
Phone: (916) 446-2591
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