What about IgG (ELISA: enzyme-linked immunosorbent assay) blood tests from a lab ?
There is …no science… that IgG blood tests are reliable indicators of problem foods. So are you cutting out foods for nothing?
Two recent studies tried to build a case for blood tests to guide foods eaten :
1) A 2015 study by Naturopaths (discussed below), failed to validate IgG blood tests. (10)
2) A 2017 Yale study (*funded by Alcat* which sells these blood test) confirms : “Patients with..IBS…are often placed on diets guided by food intolerance assays (blood tests- Ed.), although these have not been validated ” . And the study failed to prove anything beyond 50/50 chance, or luck. Details of study below. WHAT IS INTERESTING IS THAT THE 4 day ROTATION OF MILDLY REACTIVE FOODS appears to have been the reason both test Groups
3)November 2, 2018, CBC article concludes, “There is no validity”: Unproven blood tests for food sensitivity widely offered in Canada. Medical experts “including the Canadian Society of Allergy and Clinical Immunology (CSACI), call IgG tests for food sensitivities “unvalidated” and more than two dozen organizations warn about the misuse of such tests… Dr. Douglas Mack, a pediatric allergy, asthma and immunology specialist, argues the results of an IgG test are an indication that you had exposure to the foods — not an intolerance of them….Food sensitivities are different from food allergies. An allergy is an immediate, immune response, and foods like nuts and seafood are often known to cause allergic responses that can be life-threatening… Sensitivities or intolerances, on the other hand, are not related to the immune system and often take hours, if not days, to take effect — and are therefore very difficult to diagnose…By unnecessarily eliminating foods, he says he sees “kids that are coming in with nutritional deficiencies, with failure to grow very well.” A registered dietician cited said, “the radical changes the test was calling for” would have compromised the client’s health”…. Because she had “drastically cut down her foods already, because of her symptoms and her pain and not getting any answers, she was afraid to eat.” Dynacare and LifeLabs provided…. peer-reviewed studies to Marketplace, which were then analyzed by clinical epidemiologist and biostatician Jason Busse, DC, PhD. He found that “all of the studies were very problematic,” and said he was “amazed that many of them were published.” · CBC News ·
Details of the Yale Study : Above-mentioned Yale study considered some 56 (final) participants divided into two groups, over 4 weeks. Group 1 were counselled to “avoid” specific foods, “blind” to the fact these were their “severe /moderate” intolerance foods, according to Alcat blood tests; Also, ALL participants in both Groups, were counselled to a 4-day ROTATION, “blind” that these were their “mild” intolerance/reactive foods, according to Alcat blood tests. An average of 13 foods were specified per person, out of the possible 200 foods covered by the blood test. Group 2 (Comparison/Sham/Placebo) did the same, except “blind” to the fact that their “avoid” foods were actually their safe/no reactivity foods, according to Alcat blood tests.
If Alcat blood tests were an effective indicator, the following should have happened:
- Group 1 participants, with avoidance of their “severe/moderate” intolerance foods … should have expected symptom improvement
- Group 2 participants, guided to cut “safe” foods out, (arguably forcing reliance on a less safe diet)… should certainly not have expected symptom improvement, and might have shown symptom worsening.
YET SURPRISINGLY BOTH Groups showed an inexplicable marked improvement in judgement of symptoms from starting baseline to Week 4, on 100% of the measurement scales that were relied on in the study (4 measurement scales in total). Was this surprising improvement by ALL, due to the 4 Day ROTATION of reactive foods?
Two of the 4 measurement scales showed zero “0” statistical difference between Group 1 and Group 2 (50% of study tests). The other two of the 4 measurement scales (the other 50% of study tests) showed Group 1 participants felt SUBJECTIVELY better only by a “medium” amount. No objective data of any kind was collected. = It appears there is a 50/50 chance (= luck) you might subjectively feel better, to a moderate degree, if you follow Alcat blood tests. No objective data or measures were collected.
Confusingly, the Yale “Abstract” states : “Elimination diets guided by leucocyte activation tests [blood tests- Ed.] reduced symptoms”?! …. but failed to say that Elimination diets NOT GUIDED by leucocyte activation tests ALSO reduced symptoms… pretty much equally.
(**The research was funded by a grant from Cell Science Systems, Corp (Alcat) Individualized diets for irritable bowel syndrome better than placebo | YaleNews ) (The Yale study failed to explain their emphasis on only one of the four measurement scales (IBS Global Improvement Scale), when similar data quality came from all 4 measurement scales. )
- NOTICE- Did the Alcat test results confirm the benefits of 4-Day ROTATION : the only factor to benefit both Groups was the 4-day ROTATION imposed on ALL .
OVERVIEW of some other recent science re: IgE, IgG
IgE (immunoglobulin E) is widely accepted as an indication of food allergen. Reactions can be immediate symptoms (ie. asthma). But even with presence of IgE, a food challenge is needed before a diagnosis of food allergy is made. And, only then is elimination of a food from the diet recommended. This level of care to keep foods in the diet is because balanced, rich nutrition is a key to health. So even some IgE foods are not ELIMINATED from diet.
So what about IgG – mediated foods that Labs tests report on ?
Well, Labs theorize, that an IgG response might indicate a food that has delayed bad effects : in other words there is no clear link between the food and the symptom. However, recent studies suggest IgG may…on the contrary…play a PROTECTIVE role in blocking IgE reactivity…and also that higher levels of circulating IgG may simply reflect recent exposure to a food… and high levels of IgG(4) may be an indicator of higher likelihood of tolerance for the food. (See summary of studies re: IgG, in the “Discussion” of the study at ncbi.nlm.nih,gov/pmc/articles/PMC4311561/ .) 
Hold on before you ELIMINATE IgG foods. You may be unbalancing your diet… for nothing.
The above-referenced study failed to validate IgG :
While the study made clear that diet change did quickly improve symptoms, it failed to clarify why :
1) Was it simply an improved diet ? (No information given)
2) Was it simply ending the daily, repetitive eating of his favourite foods ?
3) Was it IgE foods ? The study failed to test for IgE, yet co-incidentally dealt with common IgE allergens (wheat, eggs, dairy, citrus, corn) : even stating that Patient B had an immediate reaction to eggs circa week 35, strongly suggesting IgE allergen.
4) The study failed to do follow-up testing for IgG, so no link was ever established between symptom improvements and IgG.
NO science for the elimination of IgG foods. (Study citations further confirm confusion).
What the study did make crystal clear : it is very difficult to sustain cutting out a lot of common and favourite foods, even if you see improvement. Food Rotation widens (not cuts) the diet, and works in a number of ways to keep foods in the diet. Its guidance toward whole foods and widest variety provide rich nutrition, even while reducing sensitization, by virtue of the recovery period between repeat eating of the same foods.
The RotationDietPlus Software helps manage complex diets. Consult a qualified health professional for any dietary change.
 Kulveen Virdee, ND, Jeannette Musset, BS, Matthew Baral, ND, Courtney Cronin, ND, and Jeffrey Langland, PhD (2015). Food-specific IgG Antibody-guided Elimination Diets Followed by Resolution of Asthma Symptoms and Reduction in Pharmacological Interventions in Two Patients: A Case Report. Glob Adv Health Med.2015 Jan;4(10:62-6. dos: 10.7453/gahmy.2014.068. (The study citations direct reader to the confused state of research in this area.)
 Burks AW, Jones SM, Wood RA, et al. Oral immunotherapy for treatment of egg allergy in children. N Engl J Med. 2012;367(3):233–43. [PMC free article] [PubMed]
 James LK, Shamji MH, Walker SM, et al. Long-term tolerance after allergen immunotherapy is accompanied by selective persistence of blocking antibodies. J Allergy Clin Immunol. 2011;127(2):509–16. [PubMed]
 Tomici? S, Norrman G, Fälth-Magnusson K, Jenmalm MC, Devenney I, Böttcher MF. High levels of IgG4 antibodies to foods during infancy are associated with tolerance to corresponding foods later in life. Pediatr Allergy Immunol. 2009;20(1):35–41. [PubMed]
 Ather Ali, Theresa R Weiss, Douglas McKee, Alisa Scherban, Sumiya Khan, Maxine R Fields, Damian Apollo, and Wajahat Z Mehal. Efficacy of individualized diets in patients with irritable bowel syndrome: a randomized controlled trial. BMJ Open Gastroenterology.2017;4(1):e000164 , Abstract