Immune response to food
Food sensitivity.
Your immune response across more than two hundred common foods. Not an allergy test, and not a stand-alone diagnosis.
By Genova Diagnostics · At-home finger-stick bloodspot
Why it matters
When elimination diets work but you do not know why, a food sensitivity panel collapses months of guessing into a targeted read. The panel measures IgG and IgA antibody responses to specific foods, not the IgE allergy response, but the lower-grade reactivity that may quietly drive inflammation, gut symptoms, skin issues, and energy crashes. Use it to make the elimination test precise instead of generic. Collection is an at-home finger-stick blood-spot kit shipped to you. This is a Genova specialty test; it is not a draw at LabCorp or Quest.
I want to be honest about what this test is and is not. IgG food panels are not a diagnosis of food allergy. IgG antibodies are part of the normal immune response to anything you eat regularly, and a positive marker can mean exposure rather than reactivity. The major allergy societies do not endorse IgG panels as standalone diagnostic tools, and I agree with them on that. What this panel is useful for is taking an elimination diet from a guess to a targeted experiment. If five different gluten-containing items react together and the patient's symptoms remit on a gluten-free trial, the panel helped. If one isolated food reacts and the elimination changes nothing, the panel was noise. The clinical correlation is the test, not the report.
What I read for
The pattern, not isolated reactions. Multiple gluten-containing or dairy-derived foods reacting together points to one underlying issue. A handful of unrelated foods reacting alone usually means something else (gut barrier, immune dysregulation) is driving the noise.
I read this panel as four pattern questions, none of which are answerable by a single number on the report:
- Are clusters of related foods reacting together? (the gluten family, the dairy family, the nightshade family; clusters are signal)
- Is there evidence of broad-spectrum hyperreactivity? (twenty or thirty unrelated foods reacting suggests gut barrier dysfunction, not food reactivity)
- Do the reactive foods match the patient's symptom history? (the elimination test is what confirms the panel, not the other way around)
- What does sIgA from a GI Effects panel look like alongside this? (mucosal immune tone changes how I interpret the IgG read entirely)
What it measures
The Food Sensitivity panel reads two different antibody classes across more than 200 foods. IgG is the most commonly reported, with IgA available as an add-on for mucosal-specific reactivity. Both are different from IgE, which is what classical food allergy testing reads.
What IgG actually represents. Immunoglobulin G antibodies to food proteins develop with exposure. Anyone who eats wheat regularly has measurable IgG to wheat. The clinical question is not whether IgG is present, but whether the level reflects an ongoing immune-mediated response that contributes to symptoms. The honest answer is that the science is mixed, which is why I treat this panel as a hypothesis generator for an elimination trial, not a verdict.
Why pattern matters more than positives. If five foods in the gluten family all react, the underlying issue is probably gluten itself or wheat-specific intolerance, confirmed by a gluten-free trial. If five unrelated foods react in isolation, the underlying issue is more likely loss of gut barrier integrity, where the immune system is meeting food antigens it should never see. The intervention for the second case is gut-barrier work, not endless elimination.
What sets this panel apart. Genova's panel offers both IgG and IgA testing, including the option to read mucosal-specific IgA reactivity that other panels miss. Paired with a GI Effects panel and the patient's symptom history, it becomes a useful piece of a larger gut workup. Alone, it is incomplete.
See all 87 biomarkers
Dairy
- Casein
- Cheddar cheese
- Cottage cheese
- Cow's milk
- Goat's milk
- Lactalbumin
- Yogurt
Fruits
- Apple
- Apricot
- Banana
- Blueberry
- Cranberry
- Grape
- Grapefruit
- Lemon
- Orange
- Papaya
- Peach
- Pear
- Pineapple
- Plum
- Raspberry
- Strawberry
Vegetables
- Alfalfa
- Asparagus
- Avocado
- Beets
- Broccoli
- Cabbage
- Carrot
- Celery
- Cucumber
- Garlic
- Green Pepper
- Lettuce
- Mushroom
- Olive
- Onion
- Pea
- Potato, sweet
- Potato, white
- Spinach
- String bean
- Tomato
- Zucchini
Fish and Shellfish
- Clam
- Cod
- Crab
- Lobster
- Oyster
- Red snapper
- Salmon
- Sardine
- Shrimp
- Sole
- Trout
- Tuna
Poultry and Meats
- Beef
- Chicken
- Egg white
- Egg yolk
- Lamb
- Pork
- Turkey
Nuts and Grains
- Almond
- Buckwheat
- Corn
- Corn gluten
- Gluten
- Kidney bean
- Lentil
- Lima bean
- Oat
- Peanut
- Pecan
- Pinto bean
- Rice
- Rye
- Sesame
- Soy
- Sunflower seed
- Walnut
- Wheat
Miscellaneous
- Cane sugar
- Chocolate
- Coffee
- Yeast
Who this is for
Food sensitivity testing earns its place as part of a larger gut workup or to make an elimination diet targeted instead of guessing. It is rarely the first test I order and almost never the only one.
Common reasons I order it
- Persistent gut symptoms (bloating, irregular bowel, reflux) where elimination has been attempted blindly without resolution
- Eczema, atopic dermatitis, or other skin conditions with a suspected food connection
- Energy crashes or brain fog that track with meals
- Childhood food reactivity history that may have shifted in adulthood
- Athletes refining diet for inflammation and recovery
- Patients about to attempt an extended elimination diet and wanting to focus the trial
I almost always order this alongside or after a GI Effects panel. Reading food reactivity without reading the gut barrier first is reading the alarm without checking the door.
How collection works
- 1
We decide it is the right test.
A short conversation to confirm a food sensitivity panel answers your question and that GI Effects (or other gut workup) is not the better first step.
- 2
The kit ships to your home.
Genova mails the collection pack with everything you need: a finger-stick lancet, the bloodspot card, written instructions, a collection video, and prepaid return shipping.
- 3
You collect at home.
A single finger-stick produces enough bloodspot for the panel. Clean the finger, lance, fill the marked circles, let it dry. Most people complete the whole collection in under 10 minutes.
- 4
You ship it back.
Use the prepaid FedEx materials in the kit. Genova receives the sample and runs the assays.
- 5
We read it together.
Results come back to me in about 10 to 14 business days. We sit down with them and design a targeted elimination protocol based on the pattern, not a blanket avoidance list.
How to prepare
Preparation is light because the test reads circulating antibodies, not acute reactions. A few things matter.
Eat a normal varied diet for at least 3 weeks before collection: if you have been avoiding foods, the panel will not detect reactivity to foods you have been off long enough for antibodies to fall.
Hold immunosuppressants and high-dose steroids if medically appropriate: [NEEDS YOUR INPUT: Standard hold period, typically 4 to 6 weeks before collection. Confirm and adjust. Never stop these medications without clearing it with me first.]
Fasting: not required. Eat normally before collection.
Recent antibiotic courses: if you finished antibiotics within the past 2 weeks, the gut barrier reading is shifted. We may delay collection by a few weeks for a cleaner read.
If the goal is to evaluate food reactivity after an elimination trial has already begun, we discuss timing carefully. The panel only reads what you are currently eating.
What you get
The Genova report listing IgG (and optionally IgA) reactivity across the foods tested, with quantitative levels. A debrief with me where we look for the patterns that matter and design a targeted elimination trial. The elimination is the test. The panel is the hypothesis generator.
If the trial confirms a pattern, we structure the reintroduction so we can isolate the culprits. If it does not, we move upstream to gut-barrier work, because food reactivity that does not respond to elimination usually points there.
Questions
No. Food allergy is IgE-mediated and tested separately. This panel reads IgG (and optionally IgA) responses, which are different immune classes and behave differently in the body. A true IgE food allergy can cause anaphylaxis. IgG reactivity does not.
The science is mixed. The major allergy and immunology societies do not endorse IgG panels as standalone diagnostic tools, and I agree with that position. What the panel is useful for is targeting an elimination trial. The elimination is what confirms or refutes the panel. I never tell a patient to permanently avoid a food based on this test alone.
Not really, and that is by design. It will give us a list of foods to consider testing in an elimination protocol. The result of that elimination (symptom change or no change) is the actual answer.
About 10 to 14 business days from when Genova receives the sample.
[NEEDS YOUR INPUT: This is typically cash-pay through the practice. Genova provides CPT codes for possible reimbursement, but coverage varies for IgG food panels in particular. Confirm and adjust.]
I almost always order it alongside or after a GI Effects panel. Reading food reactivity without reading the gut barrier first leaves half the picture missing. The exception is when the workup is targeted and we already know the gut barrier is intact.
How to order this
Part of the Precision Partnership baseline. Lab fee at vendor cost. I interpret the results into your written Plan.
From the writing