Understanding the Differences Between Food Allergies and Sensitivities

If your stomach has been bothering you lately, you might be wondering if you have a food allergy. Perhaps to dairy? Or maybe you have an itchy, red rash and people have mentioned that you could be allergic to gluten.  

But is it true? You know that true food allergies like peanuts and shellfish can be dramatic and even life threatening. The symptoms you are experiencing, though unpleasant, are not that. So, is it a food allergy, or is it a food sensitivity? 

Food Allergies and Food Sensitivities Are Not the Same Thing 

For starters, there are several categories of adverse food reactions. Loeb et al. have divided them between immune-mediated and nonimmune-mediated reactions. [1] The former includes food allergies and Celiac disease, whereas the latter includes food sensitivities, toxic reactions, metabolic errors, and food aversion. For the sake of simplicity, for nonimmune-mediated reactions, we’ll focus on food sensitivities, which represent the majority of adverse food reactions.  

Both food allergies and food sensitivities are reactions in your body to food. But there are some big differences between them: 

• Timing:
  • Allergic reactions to foods happen quickly—within minutes or at most hours. 
  • Sensitivity reactions are much slower, taking hours or even days. 
• Body System:
  • Allergies arise from an immune response. 
  • Sensitivities develop due to an inability to effectively process foods and the severity of the reaction is directly related to the amount of food consumed. 
• Severity:  
  • Allergic reactions to food are often severe and can be fatal. 
  • Sensitivities are rarely life threatening, but they can cause chronic discomfort.
• Testing:  
  • While food allergies are often determined by self-reported food reactions, a diagnosis should be confirmed with a medically supervised oral food challenge, the gold standard for diagnosis. [1] 
  • Because of the complexity of food sensitivities, a simple classification scheme does not exist, and there are no validated tests, except for lactose, fructose, and sucrase-isomaltose intolerances. [1] 

Symptoms of Food Allergy 

During an allergic reaction, you might experience: 

• Hives or very itchy skin, 
• Swelling or tingling of the lips, tongue, and even throat, 
• Stomach pain, nausea, vomiting, or diarrhea, 
• Respiratory swelling, wheezing, and difficulty breathing, 
• Dizziness or lightheadedness. [2] 

If these symptoms are severe, anaphylactic shock can occur. This is a potentially fatal medical emergency. Please call 911 if you think you’re having an allergic reaction.   

What Causes Allergic Reactions to Foods? 

When a person with a food allergy eats—or just touches or inhales—even a tiny amount of the food allergen, their hypersensitive immune system launches an attack. 

Immune cells bind to the food allergen and start pumping out huge amounts of immunoglobulin E antibodies. These antibodies flood the entire body with inflammatory signals. And this starts an allergic reaction. [1,3] 

According to the USDA, the nine foods that cause most food allergies are: 

1. Milk and dairy products 
2. Eggs
3. Fish
4. Shellfish
5. Tree nuts
6. Peanuts
7. Wheat
8. Soybeans
9. Sesame seeds [4]

Does The Paleo Diet® Eliminate All Nine Common Allergens? 

The Paleo Diet eliminates:

• All milk and dairy products, 
• All grains, including wheat, 
• All legumes, including peanuts and soybeans. 

RELATED: How Wheat Can Trigger Chronic Disease 

The Paleo Diet does allow fish, shellfish, and eggs, as well as tree nuts and seeds in small quantities. If you are allergic to these foods, you can modify your diet to exclude them. 

Food Sensitivities Often Start in the Gut 

A lack of digestive enzymes causes some food sensitivities known as food intolerance (Note: Some argue that food sensitivity and food intolerance are separate conditions, but the evidence is so far inconclusive. For this purpose, we will categorize intolerance as a type of sensitivity). Lactose, fructose, and sucrose intolerance are common (the number vary, but up to 50% of adults have lactose intolerance). They create digestive havoc like painful gas, bloating, and diarrhea. [1] 

Other food sensitivities stem from harmful microorganisms living in your gut. These microbes interact with certain foods to create inflammation and painful digestive issues. [5]  

Over time, inflammation in your gut can break down the lining of your digestive tract. A weak digestive lining allows food particles to escape into your blood and lymph system. This can provoke an immune response that triggers symptoms throughout your body and not just in the digestive system. 

Does The Paleo Diet Help with Food Sensitivities? 

Eliminating common reactive foods is a great way to improve digestion and overall health. [1] But knowing where to start can be overwhelming. That’s where an evidence-based diet can be helpful. For example, the two foods most likely to cause sensitivities, dairy and gluten, are not part of The Paleo Diet. 

Cutting dairy out of your diet may relieve symptoms like: 

• Stomach pain and nausea 
• Gas and bloating 
• Diarrhea [6] 

And eliminating gluten might resolve a wide range of issues like: 

• Stomach pain and bloating 
• Diarrhea or constipation 
• Headaches 
• Fatigue 
• Joint pain 
• Anxiety or depression 
• Anemia [7] 

The Paleo Diet could also relieve digestive problems associated with legumes, lunch meats, and excessive salt since these foods are also eliminated. 

Caffeine is another common food sensitivity. The Paleo Diet does allow coffee and tea in moderation, but if you experience nervousness, anxiety, insomnia, or a rapid heartbeat with caffeine, you may want to limit your intake. [8] 

RELATED: Coffee Alternatives to Consider on The Paleo Diet 

Eating for Overall Health 

Whether managing food allergies or food sensitivities, you should always work with a care provider. Follow their guidance about any symptoms you are experiencing and run any dietary changes you are considering by them first.  

Let’s face it, changing your diet can be a major challenge. But it is empowering to learn that you have more control over your health than you previously thought. Research has shown that the quality and variety of the whole diet can affect food allergies. It does this by improving both the gut microbiome and the imbalance in the immune system that leads to more extreme allergic responses. It has been proposed that the Western diet could increase allergic disease via this exact process. [9] Eating simple, nourishing foods on The Paleo Diet might not just help you feel better, but decrease the incidence of food allergies and sensitivities. 

References

1. Loeb L, Cangemi DC, Squire JD, Lacy BE. Clarifying the Hazy Concepts of Food Allergies and Sensitivities. Gastroenterology & Hepatology [Internet]. 2024 Oct [cited 2025 Jan 21];20(9):524. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11523085/  
2. Mayo Clinic. Food allergy – Symptoms and causes [Internet]. Mayo Clinic. 2021. Available from: https://www.mayoclinic.org/diseases-conditions/food-allergy/symptoms-causes/syc-20355095  
3. National Institute of Allergy and Infectious Diseases. Identifying Causes of Food Allergy & Assessing Strategies for Prevention | NIH: National Institute of Allergy and Infectious Diseases [Internet]. www.niaid.nih.gov. 2023. Available from: https://www.niaid.nih.gov/diseases-conditions/food-allergy-causes-prevention  
4. Food Allergies: The “Big 9” | Food Safety and Inspection Service [Internet]. Usda.gov. 2023. Available from: https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/food-allergies-big-9  
5. Caminero A, Meisel M, Jabri B, Verdu EF. Mechanisms by which gut microorganisms influence food sensitivities. Nature Reviews Gastroenterology & Hepatology. 2018 Sep 13;16(1):7–18. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6767923/ 
6. Mattar R, Mazo DF de C, Carrilho FJ. Lactose intolerance: diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology [Internet]. 2012 Jul;5:113–21. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401057/  
7. Biesiekierski JR, Iven J. Non-coeliac gluten sensitivity: piecing the puzzle together. United European Gastroenterology Journal. 2015 Mar 30;3(2):160–5. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4406911/ 
8. Yang A, Palmer AA, de Wit H. Genetics of caffeine consumption and responses to caffeine. Psychopharmacology [Internet]. 2010 Jun 9;211(3):245–57. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242593/  
9. Skypala I, Vlieg-Boerstra B. Food intolerance and allergy. Current Opinion in Clinical Nutrition and Metabolic Care. 2014 Sep;17(5):442–7. Available from: https://journals.lww.com/co-clinicalnutrition/Abstract/2014/09000/Food_intolerance_and_allergy___increased_incidence.12.aspxso