A200 Test: Everything You Need to Know

Most adverse reactions to food are due to food sensitivity, a reaction of the body to the ingestion of certain foods, where the body has difficulty or is unable to absorb certain nutrients. This results in extreme discomfort, which can manifest with various symptoms. The prevalence of food sensitivity in the general population is estimated to be between 5-20% (1), but due to insufficient or underdiagnosed data, the true prevalence remains unknown.

IgG-mediated food sensitivity (type III hypersensitivity reaction) is a delayed immune reaction associated with various nonspecific symptoms, such as skin rashes, hives, asthma, abdominal cramps, diarrhea, constipation, and even neurological manifestations like migraines (2).

Understanding How to Diagnose Food Sensitivity

Various factors can alter intestinal permeability or the functionality of the immune system (such as stress, infections, antibiotics, or excessive use of anti-inflammatories), increasing the likelihood of food sensitivity reactions. IgG-mediated food sensitivity can be caused by increased intestinal permeability, allowing food substances to access the circulation as antigens, leading to the production of IgG specific to food proteins (1).

Although food sensitivity is common, the diagnosis is generally not straightforward and requires an understanding of various clinical aspects, including the severity and timing of symptom onset. Due to nonspecific symptomatology, the fact that it cannot be detected in skin tests, and the lack of a quick cause-effect response, food sensitivities are even more challenging to identify (3). The complexity increases due to the various mechanisms involved, which can range from pharmacological reactions (substances that alter metabolism) to food intolerances due to enzyme deficiencies (such as lactose absorption) and nonspecific gastrointestinal dysfunctions.

However, with scientific advances, innovative tests that allow the analysis of the main foods triggering these immune reactions are becoming increasingly accessible in people’s lives. The identification of the sensitivity profile through tests that evaluate the main foods related to this type of reaction (4), from a simple serum sample, has provided better guidance in clinical management, offering greater benefits to patients.

Learn About the SYNLAB A200 Test

In this context, the SYNLAB Group developed the A200 test, which determines the presence of IgG antibodies in the serum against proteins from more than 200 foods. With a simple blood sample, it is possible to know which foods may be potentially harmful to your health.

The analysis is performed with immunoblot technology and identifies specific IgG antibodies against the proteins of these foods (antigens) directly. Thus, eliminating these foods that cause sensitivity can provide a noticeable improvement in quality of life in a high percentage of patients.

The A200 test consists of determining IgG antibodies in the serum against 216 food proteins, such as:

• Vegetables and greens: Pumpkin, Zucchini, Chard, Celery, Artichoke, Lettuce, Leek, Asparagus, Potato, Sweet potato, Eggplant, Beet, Broccoli, Mache greens, Onion, Carrot, Champignon mushroom, Mushroom, Kale, Brussels sprouts, Cauliflower, Shallot, Endive, Spinach, Turnip, Cucumber, Green Pepper, Radish, Cabbage, Red Cabbage, Arugula, Tomato and Green Beans;
• Legumes: Chickpeas, Peas, Favo beans, White beans, Red beans, Lentils and Soybeans/Soy oil;
• Dairy products and egg: Beta-lactoglobulin, Casein, Egg white, Milk/buffalo cheese, Milk/goat cheese, Milk/sheep cheese, Milk/cow cheese and Egg yolk;
• Fish and shellfish: Clam, Anchovy, Herring, Tuna, Cod, Red Sea Bream, Jumbo Shrimp/Shrimp, Escargot, Crab, Carp, Mackerel, Caviar, Dorado, Eel, Lobster, Sole, Razor clam, Pike, Squid, Hake, Grouper, Mussel, Oyster, Swordfish, Flounder, Goose Barnacle, Octopus, Sea Bass, Brill, Salmon, Sardines, Cuttlefish, Monkfish, trout, Scallop and Vongole Clam;
• Meats: Ostrich, Goat, Horse, Venison, Quail, Rabbit, Lamb, Chicken, Duck, Partridge, Turkey, Pork and Veal meats;
• Fruits: Avocado, Pineapple, Carob, Plum, Blackberry, Cranberry, Olive/Olive oil, Banana, Cherry, Coconut, Apricot, Fig, Raspberry, Black Currant, Red Currant, Kiwi, Orange, Lychee, Lime, Lemon, Apple, Mango, Watermelon, Melon, Blueberry, Strawberry, Nectarine, Papaya, Pear, Peach, Pomegranate, Date, Tangerine, Grapefruit and White Grape/Black Grape;
• Dry nuts: Almond, Cashew, Hazelnut, Peanut, Sweet Chestnut, Walnut, Brazil Nut, Macadamia, Raisin, Pine Nut and Pistachio;
• Herbs and spices: Saffron, Licorice, Caper, Rosemary, Garlic, Anise, Thistle oil, Vanilla, Chamomile, Canola oil, Black tea, Green tea, Coriander, Cumin, Clove, Curry, Dill, Fennel, Tarragon, Grape leaf, Ginger, Goji berries Peppermint/Spearmint, Laurel, Marjoram, Basil, Mustard, Nutmeg, Oregano, White/black pepper, Red pepper, Paprika, Parsley, Salvia, Hemp seed, Chia seed, Poppy seed and Thyme;
• Cereals and grains: Barley (Hordeum vulgare), Rice, Oats (Avena sativa), Cocoa, Sugarcane, Couscous, Rye (Secale cereale), Hulled wheat (Triticum spelta), Gluten, Flax seed (Linum usitatissimum), Corn (Zea mays), Malt, Millet (Panicum niliaceum), Quinoa (Chenopodium quinoa), Wheat bran, Sunflower/Sunflower oil, Sesame seed (Sesamum indicum), Durum wheat semolina (Triticum durum), Cassava/tapioca (Manihot esculenta), Wheat (Triticum aestivum), Buckwheat (Fagopyrum esculentum) and Amaranth (Amarantus);
• Others: Agar-agar, Spaghetti seaweed, Spirulina seaweed, Aloe vera, Coffee, Cinnamon, Brewer’s yeast, Bread yeast, Hops, Honey, Cola/Cola nut and Rhubarb. 

What are the indications for the A200 Test? 

The A200 test is an important option to consider in the face of any undiagnosed adverse clinical manifestations, such as:

• Gastrointestinal disorders: abdominal pain, constipation, diarrhea, abdominal; bloating, nausea, acidity, ulcers, and mouth sores, gastritis, colitis;
• Dermatological processes: acne, eczema, psoriasis, itching, hives;
• Neurological diseases: headache, migraine, dizziness, vertigo;
• Respiratory alterations: cough, bronchitis, asthma, rhinitis;
• Psychological conditions: anxiety, depression, fatigue, hyperactivity;
• Musculoskeletal disorders: pain, stiffness, arthritis, fibromyalgia;
• Others: fluid retention and obesity.

It should be considered that symptoms are nonspecific and may be common to other disorders or pathologies, therefore, their manifestation is not necessarily associated with food sensitivity. It is always advisable to consult a specialist for symptom evaluation.

A200 Test: Highly Sensitive Technique

Through a simple blood collection, the A200 test analyzes IgG using the immunoblot methodology, a highly sensitive technique capable of detecting low levels of IgG. SYNLAB collaborated with a major biotechnology company in the development and application for food hypersensitivity analysis, allowing the analysis of over 200 foods.

The evaluation of all foods is performed in duplicate, ensuring high reliability. With the obtained results, it is possible to categorize food sensitivity into 4 classes:

• Allowed foods: Foods that show no reactivity and can be consumed habitually;
• Not recommended foods: Foods that show low reactivity and may cause symptoms if consumed in excess or habitually. For these cases, a rotational diet is recommended, and chewing food well to promote mechanical breakdown of proteins;
• Foods to avoid: Foods that show moderate reactivity and have a high probability of causing symptoms if consumed in excess or habitually;
• Not allowed foods: Foods that show high reactivity and have a high probability of causing symptoms if consumed in excess or habitually.

For foods that show moderate or high reactivity in the A200 test, it is recommended to exclude them from the diet for a prolonged period (at least three months, ideally six months). Eliminating these foods from the diet provides visible improvement in approximately 75% of cases. After at least three months, foods can be gradually reintroduced into the diet.

The average time for an exclusion diet should be 4 to 8 weeks, as it is expected that symptoms will improve during this period. If after excluding a food for 3 or 4 weeks there is no improvement, it is recommended to reintroduce it, as the discomfort may be due to other causes or pathologies. After the elimination phase, one should attempt the gradual introduction of avoided foods into the diet (one at a time), observing the possible recurrence of symptoms (5).

The excessive production of IgG antibodies against foods can be due to different causes: immune system defects, viral or bacterial infections, unbalanced diet, intestinal microbiome alterations, among others. Therefore, the goal of this diet is to improve symptoms while trying to resolve the underlying cause.

To avoid specific deficiencies, it is important to emphasize that the A200 test result should be evaluated by the requesting physician, within the patient’s clinical context, ensuring appropriate and individualized recommendations and dietary plan.

The A200 test aims to analyze IgG-mediated food sensitivity. However, other types of food intolerances caused by genetic alterations or enzyme deficiencies cannot be detected by the A200 test. Just like IgE-mediated food allergies. Therefore, the A200 test result does not exclude the possibility that the individual may have an allergy to the studied foods.

Frequently Asked Questions About the A200 Test

Why take the A200 test?

Food sensitivity is a delayed immune reaction, mediated by IgG, which is associated with various nonspecific symptoms ranging from skin rashes, hives, asthma, abdominal cramps, diarrhea, constipation, and even neurological manifestations such as migraines. Identifying the foods that can lead to these symptoms helps the requesting physician establish an appropriate dietary plan for the patient.

Can my results be affected by medications?

Certain drugs like glucocorticoids or monoclonal antibodies exert an immunosuppressive effect, reducing the production of any type of IgG. Some studies indicate that these effects can last up to 6 months after the end of treatment. If you are currently undergoing or have recently undergone immunosuppressive treatment, you should not be tested. In case of doubt, consult your specialist.

My results indicate a strong reaction to cow’s milk and its derivatives. Can I consume lactose-free dairy products?

Lactose-free products are intended for people with lactose intolerance. The A200 does not detect sugar intolerances, including lactose, but sensitivity to the proteins present in foods. Therefore, if your results show elevated IgG levels compared to the proteins contained in cow’s milk, you should avoid all cow’s milk products (including those that do not contain lactose), as your body does not tolerate them well at this time.

Discover here on our blog the tests offered by SYNLAB for lactose intolerance.

I was diagnosed with malabsorption through a breath test. Why doesn’t the A200 show high reactivities against fructose-rich fruits and vegetables?

Fructose malabsorption occurs when this sugar is insufficiently absorbed in the small intestine during digestion. In these cases, most of the fructose reaches the large intestine, inducing digestive discomfort such as diarrhea or bloating. The immune system reacts against proteins (antigens) and is therefore not involved in this type of disorder, which justifies why IgG reactivities against fructose-rich products are not increased. Therefore, if you have been diagnosed with fructose intolerance and already know that certain foods of this type do not sit well with you, do not consume them regardless of the result obtained with the A200.

How is a test that detects food allergies different from tests that detect food sensitivities?

Food allergies and sensitivities are mediated by different mechanisms involving different types of antibodies. Classic allergic blood tests detect IgE antibodies, while those with food sensitivity like the A200 evaluate IgG subclass antibodies. Therefore, the results of an allergy test and a sensitivity test are not comparable. If you have been diagnosed with a food allergy, it is important that you continue avoiding the consumption of that food, regardless of the result reflected in the test.

Can the A200 test be performed on children?

Currently, there are no guidelines stipulating a minimum age for performing an IgG-based food sensitivity test. However, since the immune system of children is still developing, we do not recommend the use of the test in children under 8 years of age unless prescribed by a specialist.

I am celiac and the A200 results do not show IgG reactivity against gluten-containing foods, why?

If you are celiac, you have likely completely removed gluten-containing foods from your diet since you were diagnosed. Therefore, the IgG concentration compared to gluten foods will likely be low or undetectable, and consequently, these will appear as non-reactive foods.

My results show strong IgG reactivity to cereals or gluten-containing products, does that mean I am celiac?

The A200 test detects IgG antibodies against gluten. However, celiac patients also produce several types of antibodies that are not evaluated in this test, and therefore, the A200 cannot and should not be used to diagnose celiac disease. We advise you to consult your physician if you suspect this disease.

My results show strong IgG reactivity to gluten-rich foods, can I consume products that specify “may contain traces of gluten”?

Celiac patients produce several types of antibodies that are not evaluated in this test, and therefore, the A200 cannot and should not be used to diagnose celiac disease. If you suspect you may suffer from celiac disease, it is advised that you consult your physician.

Check out which gluten intolerance tests SYNLAB offers.

I have changed my diet, but my symptoms not improve. Why?

There are several potential reasons why dietary changes may not induce improvement. Symptoms related to food sensitivity are not specific (abdominal bloating, gas, fluid retention, dermatological problems…) and may be common to other processes or pathologies. It is important to rule out that the discomfort you present is not due to food sensitivity, but to a disease that occurs with a similar clinical presentation. If the suspicion persists, we advise you to consult your physician. However, it can also occur that you are unknowingly consuming certain food components that trigger hyperreactivity. Therefore, we advise you to pay attention to food labels and even certain cosmetic products or nutritional supplements, as they may all contain some of these components.

Can my gut microbiome influence food sensitivity?

While factors such as immune system defects, viral or bacterial infections, an unbalanced diet, or genetics, among others, can lead to food sensitivity, the gut microbiome is gaining relevance as a key factor in this pathology. A rich and balanced gut microbiome is capable of inducing tolerance responses by the mucosal immune system to different potentially harmful agents, leading to normal immune responses. However, an altered microbiome cannot maintain balance with the intestinal mucosa, leading to alterations such as interruption of intestinal permeability and loss of tolerance by the immune system, among others. This imbalance can trigger inappropriate immune responses to food components that lead to food sensitivity (6).

Understand the difference between sensitivity, intolerance and food allergy

Food allergy is a hypersensitivity that we develop to some foods, and it is mediated by class E immunoglobulins (better known as IgE) that trigger immediate reactions (called type I hypersensitivity reactions) with possible involvement of the mucosa, skin, airways, intestinal tract, and vascular system. Primary food allergy is based on the (early) sensitization of IgE against animal proteins (e.g., cow’s milk, chicken eggs) or plant proteins (e.g., peanuts, hazelnuts, or wheat). In the case of secondary food allergies, IgE against pollen proteins (e.g., birch) reacts to structurally related food proteins (with cross-reactions to stone fruits, for example).

Food allergy occurs when the body seeks to defend against the entry of certain foods, even in small amounts. By identifying them as a foreign body, the body produces antibodies for its defense. Food allergies typically appear when the patient is still very young. Sensitivity, however, can appear at any time from the difficulty of digesting a particular food, becoming more frequent as we age.

This happens because digestion becomes slower, as we decrease the production of enzymes used in food breakdown. With difficulty in the absorption process of certain nutrients, the body retains the substance, which accumulates in the stomach, and this can cause discomforts such as cramps, migraines, obesity, dizziness, nausea, psoriasis, diarrhea, arrhythmia, constipation, canker sores, fatigue, conjunctivitis, among others.

If there is a sensitivity condition, the IgG analysis test will show a significant alteration. Allergy, on the other hand, is identified when the doctor analyzes the results of the IgE test.

About SYNLAB Group

Accurate and up-to-date testing is essential for more precise diagnoses and for better treatment guidance. SYNLAB is here to help you.

We offer diagnostic solutions with rigorous quality control to the companies, patients, and doctors we serve. With over 10 years in Brazil, operating in 36 countries across three continents, we are leaders in service provision in Europe.

Get in touch with the SYNLAB team and discover the available tests.

References

1) Beyer K, Teuber SS. Food allergy diagnostics: scientific and unproven procedures. Curr Opin Allergy Clin Immunol. 2005 Jun;5(3):261-6.

2) Zhao Z, Jin H, Yin Y, Hou Y, Wang J, Tang C, Fu J. Association of Migraine with Its Comorbidities and Food Specific Immunoglobulin G Antibodies and Inflammatory Cytokines: Cross-Sectional Clinical Research. J Pain Res. 2021; 14:2359-2368.

3) Wu M, Wang X, Sun L, Chen Z. Associations between food-specific IgG and health outcomes in na asymptomatic physical examination cohort. Nutr Metab (Lond). 2022; 19(1):22.

4) Cai C, Shen J, Zhao D, Qiao Y, Xu A, Jin S, Ran Z, Zheng Q. Serological investigation of food specific immunoglobulin G antibodies in patients with inflammatory bowel diseases. PLoS One. 2014;9(11): e112154.

5) Ostrowska L, Wasiluk D, Lieners CFJ, Gałęcka M, Bartnicka A, Tveiten D. Igg Food Antibody Guided Elimination-Rotation Diet Was More Effective than FODMAP Diet and Control Diet in the Treatment of Women with Mixed IBS-Results from an Open Label Study. J Clin Med. 2021;10(19):4317.

6) Caminero A, Meisel M, Jabri B, Verdu EF. Mechanisms by which gut microorganisms influence food sensitivities. Nat Rev Gastroenterol Hepatol. 2019 Jan;16(1):7-18.

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