Food Sensitivity Testing

Find out what's quietly working against you.

Food sensitivities are not the same as food allergies. They don't cause immediate reactions, they create slow, systemic inflammation that shows up as joint pain, bloating, skin issues, brain fog, fatigue, and conditions that seem entirely unrelated to diet. Most patients who discover their food sensitivities describe it as a turning point: the piece that finally explained years of unexplained symptoms.

At Optimum Health, we use comprehensive IgG food sensitivity panels to identify your specific reactive foods, not a generic elimination diet, but a precise map of what your immune system is responding to. Results are reviewed with your provider and integrated directly into your nutrition plan.

Who it's for:

• Patients with chronic pain, inflammation, or autoimmune conditions

• Anyone with persistent digestive symptoms despite a "healthy" diet

• Athletes experiencing unexplained performance drops or slow recovery

• Patients with skin conditions, migraines, or mood dysregulation

• Anyone who has tried everything and still doesn't feel well

What to expect: Testing requires a simple blood draw. Results are typically available within 1–2 weeks and reviewed in a dedicated follow-up appointment. Your provider will explain your results in plain language and give you a practical, sustainable plan for eliminating reactors and rebuilding your diet.

IgG Food Sensitivity Testing vs. ALCAT Testing

What's the Difference, and Which One Do You Actually Need?

If you're dealing with chronic bloating, fatigue, brain fog, skin issues, joint pain, or digestive discomfort that no one has been able to explain, food reactivity testing may finally give you the answers you've been looking for.

At Optimum Health Naturopathic Clinic in SW Portland, we offer both IgG Food Panel Testing and ALCAT Testing, two of the most clinically useful tools available for identifying how your body responds to specific foods. Many patients aren't sure which test is right for them. This page explains exactly what each test measures, how they differ, and how we use both to build a precision nutrition plan around your unique biology.

IgG Food Sensitivity Testing, What It Is and How It Works

IgG (Immunoglobulin G) food sensitivity testing measures your immune system's antibody response to specific foods. When your gut is exposed to foods it's reacting to, it produces IgG antibodies, proteins your immune system creates to tag and respond to those foods. Over time, elevated IgG responses contribute to chronic, low-grade inflammation that can manifest anywhere in the body.

The critical distinction is timing. Unlike IgE reactions, the immediate, potentially anaphylactic responses measured by standard allergy testing, IgG reactions are delayed by 24–72 hours after consumption. This delay is precisely why most patients never connect their symptoms to a specific food. You eat something on Monday and feel inflamed, foggy, or bloated on Wednesday. Without testing, that connection is invisible.

What elevated IgG antibodies can cause:

• Chronic digestive issues, bloating, gas, constipation, loose stools

• Systemic inflammation and joint pain

• Brain fog and poor concentration

• Fatigue that doesn't resolve with rest

• Eczema, acne, and unexplained skin conditions

• Headaches and migraines

• Mood instability and anxiety

• Autoimmune flares

What the IgG panel tests:
Our IgG food panel screens up to 200+ common foods including gluten and gliadin, dairy proteins (casein and whey separately), eggs, soy, nuts, grains, legumes, fruits, vegetables, seafood, meats, herbs, and spices, giving you a comprehensive picture of your immune reactivity across the foods you eat most.

Who benefits most from IgG testing:

• Patients with chronic digestive complaints or diagnosed IBS

• Patients with systemic inflammatory conditions, arthritis, fibromyalgia, chronic fatigue

• Patients with skin conditions unresponsive to topical treatment

• Patients experiencing unexplained mood issues or cognitive difficulties

• Anyone who suspects food is contributing to their symptoms but can't identify the trigger

ALCAT Testing, What It Is and How It Works

ALCAT (Antigen Leukocyte Cellular Antibody Test) measures a completely different immune mechanism. Rather than measuring antibody levels in the blood, ALCAT analyzes how your live white blood cells (leukocytes) physically react when exposed to specific foods, food additives, environmental chemicals, colorings, and pharmaceutical compounds.

When a reactive substance is introduced to your white blood cells in the lab, the cells change in size and volume, they activate, swell, and fragment. ALCAT quantifies the degree of this cellular response and classifies each food as severe, moderate, mild, or non-reactive. This reaction pattern reflects your innate immune system, the older, faster, broader branch of immunity that operates below the level of antibody production.

ALCAT reactivity has been clinically associated with:

• Irritable bowel syndrome (IBS) and functional GI disorders

• Unexplained weight gain and difficulty losing weight despite dietary changes

• Chronic fatigue and fibromyalgia

• Migraines and chronic headaches

• Eczema, psoriasis, and chronic urticaria

• Metabolic syndrome and insulin resistance

• Attention and cognitive difficulties

• Chronic sinusitis and respiratory issues

What the ALCAT panel tests:
The ALCAT test screens up to 450 items, including foods, food additives and colorings, environmental molds, medicinal herbs, antibiotics, and anti-inflammatory drugs. This broader scope is what makes ALCAT particularly valuable for patients whose symptoms may be driven by food chemicals, preservatives, or additives rather than whole foods alone.

Who benefits most from ALCAT testing:

• Patients with IBS or chronic GI dysfunction with no clear dietary trigger identified

• Patients struggling with unexplained weight management despite clean eating

• Patients with chronic migraines not responding to standard interventions

• Patients with metabolic or inflammatory conditions complicated by unknown dietary factors

• Patients who have already eliminated common reactive foods with partial but incomplete improvement

Which Test Is Right for You?

The honest answer is that these tests are complementary, not competing. They measure different immune pathways and reveal different layers of food reactivity. Many of our patients benefit most from running both, because IgG and ALCAT together give you a complete picture of how your immune system and your cells respond to food, at every level.

That said, here's a practical guide to help you think through your starting point:

Start with IgG Food Panel Testing if:

• Your primary symptoms are digestive, inflammatory, or skin-related

• You suspect specific foods are triggering your symptoms but can't identify which ones

• You have a confirmed or suspected autoimmune condition

• You want to identify and eliminate immune-activating foods as part of a gut healing protocol

Start with ALCAT Testing if:

• Your symptoms include unexplained weight issues, metabolic dysfunction, or persistent IBS despite dietary changes

• You react to foods that don't show up as problematic on standard sensitivity panels

• Your symptoms include migraines, chronic fatigue, or fibromyalgia

• You eat a generally clean diet but still feel inflamed or symptomatic, suggesting additives or chemicals may be the trigger

Run both tests if:

• You have complex, multi-system symptoms that haven't responded to elimination diets

• You want the most comprehensive nutritional intelligence available to build your protocol

• You are working with us on a comprehensive clinical nutrition or functional medicine plan

At Optimum Health, both tests are interpreted by your provider in the context of your full clinical picture, not handed to you as a raw data report to figure out on your own. Your results are integrated directly into a personalized elimination and reintroduction protocol, a clinical nutrition plan, and where appropriate, a Nutrigenomix-guided nutritional strategy.

Frequently Asked Questions

Is food sensitivity testing the same as food allergy testing?
No. Standard allergy testing measures IgE antibodies, the immune proteins responsible for immediate, potentially severe reactions like anaphylaxis. IgG and ALCAT testing measure entirely different immune mechanisms involved in delayed, chronic, low-grade reactions. Most people with significant food sensitivities test completely negative on standard allergy panels.

Do I need to fast before testing?
We recommend fasting for 4 hours before your blood draw and eating your normal diet in the days leading up to the test, including foods you suspect may be reactive. Avoiding suspected foods before testing can suppress the immune response and skew results.

Will I have to give up my favorite foods forever?
Not necessarily. Many food sensitivities are driven by gut permeability ("leaky gut") rather than permanent immune programming. As we heal the gut and reduce systemic inflammation, many patients are able to reintroduce previously reactive foods without symptoms, particularly those classified as mild or moderate reactors.

Can I run both tests at the same blood draw?
Yes. Both tests require a blood draw, and in most cases we can coordinate a single draw that satisfies the sample requirements for both panels. Ask your provider at your initial consultation.

How is this different from doing an elimination diet on my own?
An elimination diet removes common suspects, gluten, dairy, soy, eggs, and monitors symptoms. It's a useful starting point but has significant limitations: it can take months of guesswork, it misses individual reactive foods that aren't on the standard elimination list, and it tells you nothing about additives, chemicals, or less common triggers. Testing gives you a precise, personalized map of your reactivity in 1–2 weeks.

• IgG Food Panel

  • Immune pathway: IgG antibody

  • Items screened: 200+ foods

  • Results consultation included

  • Integrated nutrition protocol included

  • Ideal for: inflammation, gut issues, skin conditions, autoimmune tendencies

• ALCAT Test

  • Immune pathway: cellular innate immune response

  • Items screened: 450 foods, additives, and chemicals

  • Results consultation included

  • Integrated nutrition protocol included

  • Ideal for: IBS, weight concerns, migraines, fatigue

IgG Food sensitivity test compared with ALCAT test

• Both Panels (Combined)

• Immune pathway: complete coverage (IgG + cellular)

• Items screened: 600+ combined

• Results consultation included

• Integrated nutrition protocol included

• Ideal for: complex, multi‑system cases