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Food Allergy vs. Food Intolerance : Here’s How to Tell
Allergy vs Intolerance of Food
Ever felt bloated, itchy, or just plain awful after eating certain food, and wondered: was that an allergy? or just a sensitivity?
While both food allergies and food intolerance are considered as “food sensitivities” and share some similar symptoms, they’re actually quite different in how they affect your body.
Food allergy vs. food intolerance: Same-Same? Not Quite!
In this article, we’ll break down the key differences between food allergies and intolerances, why it matters, and how to figure out what your body is really reacting to.
Food Allergies – When Your Immune System Fights Food
Just like with common allergies, food allergies occur when your immune system launches an overactive response to certain molecules in food.
Imagine your immune system as a security guard that’s a bit overzealous. When it spots specific proteins in some foods, it sounds the alarm and sends out troops to fight back. Basically, your body’s just trying to keep you safe but ends up causing a bit of chaos instead.
Food allergies can cause a range of symptoms and signs of a typical allergic reaction after ingesting small amounts of certain foods, such as skin itching, swelling lips or throat, stomach pain, light-headedness, or breathing difficulty. In severe cases, if left untreated, allergy can cause a life-threatening reaction called “anaphylaxis”.
Examples of common food allergens include dairy milks, eggs, peanuts, tree-nuts (like walnuts), soy, wheat, fish, shellfish (like shrimp and crabs), and sesame. These food items are also known somewhat infamously as the “Big 9” [1].
Recent studies [2,3] indicate that food allergic reactions result from a complex interplay of genetic, environmental, and immunity factors. In most cases, these reactions are primarily associated with immunoglobulin E (IgE) antibodies [4].
Food Intolerance – When Your Body Says “Not Today”
On the other hand, food intolerance is usually milder, not life-threatening, and typically doesn’t involve the immune system.
Ever heard of lactose intolerance? Yep, that’s a common example.
Lactose is a type of sugar found in milk, mainly present in dairy products. For people with lactose intolerance, this particular food can cause discomforts because their digestive system lacks enough of the enzyme lactase, which is needed to properly break down lactose for absorption.
When lactose remains undigested, it gets fermented by bacteria in the intestines, causing symptoms like bloating, stomach pain, gas, or diarrhea, which are common symptoms of food intolerance.
Certain types of food ingredients, like histamine, gluten (a protein found in wheat), or some food preservatives, can cause common food intolerance. Eating these foods may trigger adverse reactions in people with histamine intolerance, gluten intolerance, gluten sensitivity, or sensitivity to food additives [4].
How It Might Affect Food Intake?
Both food intolerances and food allergies can lead to significant nutritional concerns, particularly when food avoidance or elimination of key food groups without adequate substitutes.
Common risks include deficiencies in protein, calcium, vitamin D, B vitamins, iron, zinc, and omega-3 fatty acids, which can impair growth and development, especially in children. For example, avoiding cow’s milk may lead to calcium and vitamin D deficiency; eliminating eggs, wheat, or fish can reduce intake of essential nutrients like B vitamins, iron, and healthy fats.
Cutting out foods without proper diagnosis can hurt nutrition and well-being. Kids with milk allergies may need special formulas, and not all substitutes are safe. Smart food swaps, supplements, and dietitian/nutritionist support help, along with regular check-ins and careful reintroductions.
What’s The Difference Between A Food Allergy and Food Intolerance
| Aspects | Food Allergy | Food Intolerance |
| Immune system involvement | Yes | Minimal-to-no |
| Type | Systemic reactions | Localized reactions |
| Time of signs and symptoms | Faster onset | Usually appear some time after the food is eaten |
| Severity | Can be severe and life-threatening | Usually milder and causing stomach discomfort |
| Common diagnostic methods | Skin prick test (SPT), IgE antibody blood test, Supervised oral food challenge (OFC) | Varies |
| Common managements | Require stricter avoidance of allergen, and standing-by emergency meds like epinephrine | Relieves by controlling amount of consuming offending food |
| Examples of food components | “The Big 9” |
Lactose, gluten, |
Lifestyle and Dietary Management
Food allergies require complete avoidance of triggers and suitable substitutes, like specialized formulas for infants with cow’s milk allergy. Those at risk should always carry an epinephrine auto-injector. Allergy shots and biologic medicines like dupilumab are also helping manage allergies better.
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People with food intolerance usually manage symptoms with a flexible approach. For example, those with lactose intolerance experience symptoms from lactose found in milk and dairy, so they switch to lactose-free milk and dairy products. They may then slowly reintroduce foods to see if symptoms return and adjust their diet as needed.
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Either way, it’s important for people with food allergy or intolerance to carefully read food labels and understand the ingredients in the food they eat. Food standards codes help food businesses provide clear information on pre-packed foods, so people can avoid or control the amounts of the food triggers.
If they suspect a food is “triggering”, being cautious about how the food is prepared and knowing what to do is essential, since there is no cure for food allergy or intolerance.
Engage a dietitian/nutritionist is important, especially for long-term or uncertain cases, to ensure nutritional adequacy and safe reintroduction strategies
Summary:
- Food intolerance can cause symptoms but does not involve the immune system.
- Intolerance to food is a type of reaction that happens after eating the food.
- Symptoms may appear delayed and are usually less severe.
- Food allergy happens when the immune system reacts to the food eaten.
- Symptoms appear quickly after eating and can be severe.
- If you think you have a food issue, track the food eaten and symptoms caused by the food.
- Engaging a dietitian/nutritionist is important in helping ensure balanced nutrition, and safe food reintroduction in cases of food intolerance or allergy.
Further References:
- USDA. 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
- Lopez CM, Mendez MD. Food Allergies [Internet]. Nih.gov. StatPearls Publishing; 2019. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482187/
- Eric, Brit Trogen, Brady K, Ford LS, Wang J. The Natural History and Risk Factors for the Development of Food Allergies in Children and Adults. Current Allergy and Asthma Reports. 2024 Feb 28;24(3)
- Gargano D, Appanna R, Santonicola A, De Bartolomeis F, Stellato C, Cianferoni A, et al. Food Allergy and Intolerance: A Narrative Review on Nutritional Concerns. Nutrients. 2021 May 13;13(5):1638.
Disclaimer: This article is for educational purposes only. Please consult your healthcare provider for medical advice tailored to your individual health needs.
Disclaimer: This article is for educational purposes only and is not a substitute for medical advice. Please consult your doctor or dietitian/nutritionist for personalized care.
