If you’ve ever experienced bloating, fatigue or skin problems after eating, you might have wondered whether or not you have a food allergy or intolerance. One way to determine if an allergy or intolerance is the culprit of your symptoms is through a food intolerance test.
Today, food intolerance testing has become a popular tool for anyone trying to see or discover the root causes of various health complaints. However, there’s still a lot of confusion about how these tests work, what they mean and whether or not they’re truly reliable.
Do you suspect you have a food intolerance or allergy? Make an appointment with a gastroenterologist to discuss your symptoms and options.
What is a food intolerance?
A food intolerance is when your body has difficulty digesting a particular food, which usually leads to having symptoms like bloating, gas, stomach cramps, fatigue or even headaches. An intolerance is different from a food allergy, which involves your immune system and can cause more immediate and sometimes life-threatening reactions, like anaphylaxis, hives or swelling.
An example of how these differ is someone who is lactose intolerant versus someone who has a peanut allergy. One of the most well-known intolerances is lactose intolerance, which affects the body’s ability to digest lactose, a sugar found in dairy products. While uncomfortable, this condition does not involve an allergic reaction and is not life-threatening.
A peanut allergy, however, can lead to someone going into shock.
Intolerance, allergy or sensitivity?
These three terms are often confused. However, they are technically different. Each causes different reactions and can require different treatment.
- Food allergy: An immediate and sometimes severe allergic reaction caused by an immune response (typically IgE antibodies). Symptoms can include rash, swelling, vomiting and anaphylaxis. This is a true medical emergency.
- Food intolerance: A non-immune reaction that typically involves your digestive system. Symptoms may develop hours after eating and are usually not life-threatening. Lactose intolerance is the most common example.
- Food sensitivity: A broader and less clearly defined term that some use to describe delayed or mild reactions possibly involving IgG antibodies. These are often identified through sensitivity tests, though the science behind them is debated.
What is a food intolerance test?
A food intolerance test, sometimes called a sensitivity test, usually involves analyzing a blood sample for IgG antibodies that may react to certain foods. The theory is that elevated IgG levels suggest a food sensitivity, which might be causing chronic symptoms.
These blood tests usually assess dozens or even hundreds of foods, ranging from common allergens to herbs and spices. You receive your test results in a few days or weeks, often with a list of “reactive” foods you’re advised to avoid.
Do food intolerance tests work?
Many experts and organizations, including the American Academy of Allergy, Asthma and Immunology (AAAAI), have said that IgG antibody testing is not a reliable way to diagnose food intolerances or food allergies. That’s because IgG antibodies are produced as a normal immune response to food exposure and are not necessarily a negative reaction.
For example, your body may produce IgG antibodies to eggs or wheat because you eat those foods regularly, not because your body reacts poorly to them.
The role of elimination diets
Most dietitians and doctors recommend using an elimination diet to identify food intolerances rather than relying solely on intolerance testing.
Here’s how it works:
- Remove the foods you think may be causing an issue from your diet for two to six weeks.
- Reintroduce each food one at a time, monitoring your body’s response.
- Track any symptoms like fatigue, bloating, skin changes or headaches.
Even though it’s time-consuming, this method is considered the gold standard for identifying food-related symptoms and is backed by clinical evidence.
Common food intolerances and sensitivities
Some of the most frequently reported food intolerances and sensitivities include:
- Lactose intolerance: Difficulty digesting lactose in dairy products
- Gluten sensitivity (not celiac): Symptoms after eating gluten without celiac disease
- Histamine intolerance: A reaction to histamine-rich foods like aged cheese, wine and fermented products
- FODMAPs: Poorly absorbed carbohydrates that can cause digestive discomfort in people with IBS
Symptoms from these conditions can range from mild to very disruptive, but they’re rarely life-threatening.
When to consider a food intolerance test
Even though the accuracy of many commercial tests is questionable, intolerance testing may still offer some benefit as a starting point, especially if you pair it with an elimination diet. You should also consider working with a registered dietitian to interpret your test results and ensure you’re not unnecessarily eliminating nutritious foods.
However, relying too heavily on a sensitivity test can lead to a restricted diet, nutritional deficiencies and even the development of an eating disorder. Approach results critically and avoid extreme dietary changes without professional guidance.
How to understand test results
Prepare yourself for a long list of foods flagged as problematic if you choose to take a food intolerance test. Remember:
- High IgG levels are not definitive proof of a food sensitivity
- Cross-reactivity can lead to false positives
- Test results should never replace a proper medical diagnosis
Instead of eliminating every food on the list, use the results to guide an elimination diet and carefully reintroduce items one at a time to assess real-life reactions. Working with a registered dietitian can help you navigate this diet to ensure you follow it properly while still consuming enough nutrients.
When to see a doctor
You might be experiencing a food allergy and should go to your nearest emergency department if you experience symptoms:
- Difficulty breathing
- Severe rash or hives
- Swelling of the face or throat
- Sudden vomiting or diarrhea
These are signs of a true allergic reaction, not a sensitivity or intolerance.
How we can help
You should speak with your primary care provider or an allergist if you think you have a food allergy, have a family history of allergies or suffer from ongoing digestive problems without a clear cause.
Before making major dietary changes or beginning food intolerance testing, make an appointment with a gastroenterologist. They can help you navigate the results and refer you to a registered dietitian for nutritional guidance.
Learn about the gastroenterology and digestive health services we offer at Mercy Health.
