Can you Test for Food Intolerance?

by | Nov 16, 2023

In today’s fast-paced world, we often seek quick solutions to our health concerns. It’s understandable why a blood test or hair test promising to identify problem foods or the underlying cause of our symptoms might sound appealing. However, diagnosing and treating food sensitivity is a complex and time-consuming process that often requires systematic elimination and reintroduction. This post explores the most popular tests and diets for food sensitivity/intolerance, and examines their scientific support.

IgG food antibody testing

IgG food antibody testing is a type of blood test that measures the levels of IgG antibodies (proteins produced by the immune system that help to identify foreign substances in the body) specific to certain foods in a person’s blood. The theory behind this testing is that high levels of IgG antibodies may indicate a sensitivity or intolerance to those particular foods. However, it is important to note there is not enough scientific evidence to support the reliability and clinical utility of IgG testing, in fact, research shows that the presence of IgG is likely a normal response of the immune system to exposure to food, rather than the presence of an intolerance/sensitivity (1).

Hair analysis

Hair analysis is a method that claims to identify food sensitivities or intolerances by analysing a person’s hair sample. It is believed that certain compounds or elements present in the hair can indicate the presence of food sensitivities. Hair testing often claims to use the bioresonance method for food sensitivity testing which involves using a device to measure the energy emitted from food molecules when they interact with the patient’s collected body hairs. By comparing the frequency of each food molecule to known reference frequencies, any changes in frequency that align with food intolerance symptoms can indicate an intolerance or sensitivity to that specific food. As high-tech as it sounds, unfortunately, there is no scientific evidence to support hair analysis as a reliable method for diagnosing food sensitivities or intolerances.


Kinesiology is a diagnostic method claiming to assess food intolerances by using muscle testing to identify how the body reacts to certain foods. By applying gentle pressure to specific muscles while testing different foods, practitioners believe they can determine if a food is causing an adverse reaction in the body. While this noninvasive test sounds appealing, unfortunately, there is no scientific evidence to support kinesiology as a diagnostic tool for food intolerance (2).

Vega tests

Vega testing is a method for diagnosing food intolerance that involves using a device that measures the electrical resistance of the body when exposed to certain foods. Based on the changes in electrical resistance, practitioners believe they can determine if a food is causing an adverse reaction in the body. Unfortunately, VEGA testing has no diagnostic accuracy or reproducibility and thus is not recommended (3).


The ALCAT (Antigen LeukoCyte Antibody Test) is a type of food intolerance test that measures the body’s immune response to various foods. It analyzes white blood cells and measures the reaction to different food antigens. The test claims to identify food intolerances and sensitivities that may be causing symptoms such as digestive issues, migraines, fatigue, and skin problems. However, it is important to note that the scientific validity and reliability of the ALCAT test have been questioned, and it is not widely accepted or recommended by medical professionals.

Hydrogen breath test

The Hydrogen breath test is a diagnostic test used to identify food intolerances, particularly those related to carbohydrates. During the test, the patient consumes a specific carbohydrate, such as lactose, fructose or sucrose, and then breathes into a device that measures the levels of hydrogen in their breath. If there is an intolerance to the carbohydrate, it can lead to the production of excess hydrogen gas in the digestive system. Elevated levels of hydrogen in the breath indicate a potential food intolerance, the most common one being lactose intolerance. Fortunately, hydrogen breath tests are supported by scientific evidence (4). However, it should be noted that just because a test may be positive, you may not have symptoms, in which case, there may not be a need to intervene.

Low FODMAP diet

The Low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet is a diagnostic tool used to identify and manage food intolerances, particularly those related to irritable bowel syndrome (IBS). FODMAPs are a group of carbohydrates that can be poorly absorbed by some individuals, leading to symptoms such as bloating, gas, and abdominal pain. The diet involves temporarily eliminating high FODMAP foods from the diet and then reintroducing them systematically to identify which specific FODMAPs trigger symptoms. The Low FODMAP diet was developed by researchers at Monash University in Australia and has been shown to be effective in managing symptoms of IBS in numerous clinical trials (5). The diet has been recommended by healthcare professionals, including registered dietitians, as an evidence-based approach for identifying and managing food intolerances related to FODMAPs.

RPAH elimination diet

The RPAH elimination diet is a dietary approach used to identify and manage food intolerances. It involves removing certain foods from the diet that are known to commonly cause reactions, such as dairy, wheat, eggs, and certain fruits and vegetables. After a period of strict elimination, individual foods are gradually reintroduced to determine which ones may be causing symptoms. This process helps identify specific food intolerances and allows individuals to modify their diet accordingly. An evidence-based approach, the RPAH elimination diet has been extensively researched and is commonly recommended by dietitians to manage food intolerances.

Disaccharide free diet

Congenital sucrase isomaltose deficiency (CSID) is a rare genetic condition where individuals lack disaccharidase enzymes, specifically sucrase, isomaltase, and sometimes lactase as well. This condition results in the malabsorption of these sugars, leading to chronic diarrhea, bloating, and abdominal pain. While typically diagnosed through a biopsy of the small intestine, it can be identified through a disaccharide-free diet which involves avoiding foods like lactose (found in dairy products), sucrose (table sugar), and maltose (found in some grains and sweeteners). Unfortunately, While CSID can’t be cured, it is hoped that as individuals age, their bodies will naturally produce more of the enzymes needed to digest certain sugars, but this does not always happen. Dietitians will often use a disaccharide-free diet followed by food reintroduction and personalisation to diagnose and manage the condition.


It’s important to consider that while studies supporting IgG food antibody testing, hair analysis testing, kinesiology, vegas testing, and the ALCAT can be found online, often these studies use very small sample sizes, lack rigorous, blinded trials, and are funded by companies selling the tests. Individuals who are considering using these unvalidated and often expensive tests should be aware that they may result in unnecessary food restrictions, which can potentially lead to nutritional inadequacies and a variety of health issues.

To get to the bottom of your symptoms, it is therefore recommended to consult with a healthcare professional (dietitian, GP, allergist) to determine the most appropriate approach for evaluating food sensitivities.



(1) Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. 2016 Aug;33(4):253-6. doi: 10.5114/ada.2016.61600. Epub 2016 Aug 16. PMID: 27605894; PMCID: PMC5004213.

(2) Schwartz SA, Utts J, Spottiswoode SJ, Shade CW, Tully L, Morris WF, Nachman G. A double-blind, randomized study to assess the validity of applied kinesiology (AK) as a diagnostic tool and as a nonlocal proximity effect. Explore (NY). 2014 Mar-Apr;10(2):99-108. doi: 10.1016/j.explore.2013.12.002. Epub 2013 Dec 18. PMID: 24607076.

(3) Katelaris CH, Weiner JM, Heddle RJ, Stuckey MS, Yan KW. Vega testing in the diagnosis of allergic conditions. The Australian College of Allergy. Med J Aust. 1991 Jul 15;155(2):113-4. doi: 10.5694/j.1326-5377.1991.tb142141.x. PMID: 1857287.

(4) Rana SV, Malik A. Hydrogen breath tests in gastrointestinal diseases. Indian J Clin Biochem. 2014 Oct;29(4):398-405. doi: 10.1007/s12291-014-0426-4. Epub 2014 Mar 21. PMID: 25298621; PMCID: PMC4175689.

(5) Nanayakkara WS, Skidmore PM, O’Brien L, Wilkinson TJ, Gearry RB. Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date. Clin Exp Gastroenterol. 2016 Jun 17;9:131-42. doi: 10.2147/CEG.S86798. PMID: 27382323; PMCID: PMC4918736.

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DISCLAIMER: This article is for informational purposes only. It is not intended to constitute or be a substitute for professional medical advice, diagnosis, or treatment. 


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