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Free patient course
Some foods can make you feel unwell hours or even days after you eat them. This course explains why. You will learn how IgA and IgG food sensitivities form and what they can do in your body. You will also see what happens when you stop eating a food for a few months while your gut heals.
Before you start. We made this course to help you understand your body. Still, no online course can take the place of a qualified health professional who knows you and your health history. Use what you learn here to have a better talk with your provider. Please check with them before you change your diet, stop a medicine or start a supplement.
Call 911 if you have trouble breathing, or swelling of your face, lips or throat, after eating.
Lesson 1 of 10 · 2 min
Many clinicians think food sensitivities start at the wall between your food and your body. This lesson shows how that wall works.
Your gut is a long tube. Food moves through it as you digest. The inside of the tube is lined with a wall of cells. This wall is only one cell thick.
The lining has two jobs. It lets water and nutrients from food into your body. It also keeps out germs and big bits of food that are not fully broken down.
See the difference
Top to bottom: inside your gut, the mucus layer, the lining cells, then inside your body, with blood at the bottom.
When the lining is healthy, only small amounts of food protein get through. Immune cells check them and learn that the food is safe. This is called oral tolerance (Pabst 2012).
When the lining is damaged, the seals loosen. More food protein slips between the cells. Doctors call this increased intestinal permeability. Many people call it leaky gut (Camilleri 2019).
Lesson 2 of 10 · 3 min
People often use these words as if they mean the same thing. They don't. Each one works in a different way and needs a different plan.
Which one is it?
0 of 5 done
Pick the best match for each person.
Lesson 3 of 10 · 3 min
A food sensitivity test looks for two kinds of antibodies: IgA and IgG. Here is what each one does.
Antibodies are Y-shaped proteins made by your immune system. Each one sticks to one target, like a germ or a food protein. This marks the target so your body can deal with it.
The gut lining's antibody
The blood's main antibody
Some types can stir up inflammation. One type does the opposite (Vidarsson 2014).
| Type | Can it switch on inflammation? |
|---|---|
| IgG1 | Yes |
| IgG2 | Only a little |
| IgG3 | Yes, strongly |
| IgG4 | Very little. This is the calm type. It is linked with eating a food often without problems (Ruiter 2007; Stapel 2008). |
Words to know
What about IgE? IgE is the allergy antibody. It causes fast reactions like hives and swelling. Allergy testing is a separate test.
Lesson 4 of 10 · 3 min
Many clinicians think a sensitivity starts when the gut lining is under strain, not with the food alone. Step through this model below.
Five steps
Top to bottom: inside your gut, the mucus layer, the lining cells, then inside your body, with blood at the bottom.
Why do the foods you eat most show up?
Your immune system reacts to what it sees most. So foods you eat every day, like dairy, eggs or wheat, often show the highest results. A high result can just mean you eat a food a lot (Stapel 2008). It can also point to a problem food. Only a trial off the food can tell.
How sure are we?
Some parts of this model are well studied, like what makes the gut leakier. Other parts are not yet proven, like whether a leaky gut causes food sensitivities, or whether immune complexes cause symptoms.
Lesson 5 of 10 · 2 min
Food sensitivity symptoms are slow. They often start hours after a meal. Patients report that some take up to 3 days. That delay makes the cause hard to spot.
Why can a gut problem cause symptoms in other places? After a meal, antibodies can grab food proteins and form clumps called immune complexes. Healthy people make some of these too, and the body clears them (Paganelli 1981).
In larger amounts, these clumps and other signals of inflammation travel in the blood. This may explain why some people feel symptoms far from the gut.
Choose a part of the body
Bars show how much research there is.
Keep a log
Patient reports matter. But for some symptoms, research is still thin. Your own food and symptom log is one of the best guides you have.
Some gut symptoms need a checkup first. See your provider soon, before you try a diet, if you have blood in your stool, black stools, weight loss without trying, low iron, or new gut symptoms that started later in life, such as after age 50. Also tell them if a close family member had colon cancer, IBD or celiac disease (ACG 2021).
Lesson 6 of 10 · 3 min
A food sensitivity test measures IgG and IgA antibodies to many foods from one blood sample. Here is how to read it, and what it can't tell you.
Sample report
Example only, not a real patientTap a food to see what its result may mean.
What the research says
The bottom line: use the test as a map. The proof is how you feel when the food is gone, and when it comes back.
Many high results?
If many foods come back high, especially on IgA, many clinicians see it as a sign that the gut lining needs repair. It does not always mean that each of those foods is a problem.
All IgA results low?
Some people make very little IgA. This can make every IgA result look low. If all your IgA results are low, ask if your total IgA was checked.
Thinking of going gluten-free? Ask for a celiac blood test first. The test is not accurate once you stop eating gluten (ACG 2023).
Before you take foods out, talk with your provider if:
Taking foods out for months can leave you short on nutrients. Your provider can help you plan.
Want to get tested?
We offer the IgG Food Explorer from Diagnostic Solutions Laboratory. It checks IgG antibodies to more than 250 foods. You prick your finger at home and mail the kit back. Results take 7 to 10 days.
This test does not check for food allergy. If a food gives you hives, swelling or trouble breathing, see an allergist instead.
A test is one piece of the picture. Your results make the most sense when a clinician who knows your health goes over them with you. You can add a 45-minute results visit when you order.
For adults in Washington and Idaho. You will finish your order on the Evexia Diagnostics website.
Lesson 7 of 10 · 3 min
Here is what happens in your body when you stop eating a trigger food for a few months and heal your gut at the same time.
How fast old antibodies fade
Week 12
"Old" means antibodies made before you stopped the food. This chart uses average half-lives: about 6 days for IgA and about 21 days for IgG (Morell 1973; Morell 1970). It shows only how fast those antibodies break down. It does not predict your test results. Some immune cells can keep making antibodies for months or years, even without the food (Amanna 2007). So real results usually fall more slowly, and may not reach zero.
| Week | Old IgA left | Old IgG left |
|---|
Before and after
Top to bottom: inside your gut, the mucus layer, the lining cells, then inside your body, with blood at the bottom.
What does not change
Your immune system keeps memory cells for years. If your gut gets leaky again, or you eat a food in large amounts every day, the sensitivity can come back.
In one trial, IBS symptoms got worse again when people went back to their old diet after 3 months (Atkinson 2004). Time off a food does not always end a sensitivity. That is why foods come back one at a time.
No trial has yet tested a long break plus gut healing, followed by bringing foods back. Much of this lesson is based on how the immune system works, not on direct trials.
Lesson 8 of 10 · 3 min
Taking a food out is only part of the plan. The gut lining also needs to heal. Many functional medicine clinicians use a plan called the 5Rs.
A fair warning about the research
Research on gut healing is still growing. Studies show that many things make the gut leakier, and some things help it heal. It is not yet proven that fixing a leaky gut is what makes symptoms better, in the gut or anywhere else in the body. A 2019 expert review says diets, fermented foods and supplements for leaky gut still need more proof (Camilleri 2019).
Your provider will choose the steps, products and doses that fit you. Do not stop a prescribed medicine or start a supplement without talking to your provider.
Lesson 9 of 10 · 4 min
After a few months, once your symptoms are calm, you can start testing foods again. Your provider will help you pick the time. Many plans start between 3 and 6 months.
Call 911 right away if, during a test, you have trouble breathing, throat tightness, swelling of the lips, tongue or face, hives all over, repeated vomiting, or you feel faint. If you have an epinephrine auto-injector, use it, then call 911.
Your food planner
Example planThe foods below are an example. Change them to match your own list. Put the foods with your lowest test results first and your highest last.
Your plan is saved in this browser only.
Lesson 10 of 10 · 2 min
Once your foods are back, a few habits help keep your gut calm and your sensitivities from coming back.
The big ideas
Want to get tested?
We offer the IgG Food Explorer from Diagnostic Solutions Laboratory. It checks IgG antibodies to more than 250 foods. You prick your finger at home and mail the kit back. Results take 7 to 10 days.
This test does not check for food allergy. If a food gives you hives, swelling or trouble breathing, see an allergist instead.
A test is one piece of the picture. Your results make the most sense when a clinician who knows your health goes over them with you. You can add a 45-minute results visit when you order.
For adults in Washington and Idaho. You will finish your order on the Evexia Diagnostics website.
Final quiz
8 questions. Pick one answer for each, then check your answers.
Sources
These studies and expert reports were found through PubMed. Each link opens the paper's DOI or PubMed page.
Schedule a free 15-minute call with a clinician. We will talk about your health and answer your questions. We serve adults in Washington and Idaho by telehealth.
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