What Food Sensitivity Testing Doesn’t Tell You

by in Blog April 4, 2018

…Why We Need More Than Testing

It’s very common in my work for a client to walk in with their IgG food sensitivity test from 3 years ago that they still use as a guide. How they are able to restrict many foods for years is beyond me! 

The goal of a good nutrition intervention should always be to increase the resiliency of the body so you can tolerate the most foods possible. Variety is the spice of life! Just ask the bacteria in our GI tract. 

Our bodies have more bacterial cells than human cells! Gross, but true.

We have the best chances of a healthy diverse gut microbiome and obtaining all the different nutrients we need when we aren’t heavily restricting foods. This was shown in a study of IBD patients: those excluding foods had significantly more nutrient deficiencies.

That being said, we do have to eliminate foods when we are really inflamed that could be contributing.

The problem is:

We have MANY ways we can react to a food. We have 5 antibodies: IgE, IgE, IgA, IgM, and IgD. There is also complement, which greatly magnifies the antibody response. We could just not break down or absorb the food correctly because we lack the stomach acid, enzyme, or bile. The food could be feeding a bad guy in our stomach, causing issues. Or we could react to traits of the food, such as histamine in aged foods, or lectins in nightshades. OH MY! So many ways.

So what do we do? I always start with elimination diets, then use the testing if we haven’t gotten the results expected, which hardly ever happens. The test just tells us what else could possibly be causing issues, not what you can or can’t eat. This is why research on the testing is controversial and inconclusive.


  • 97 obese adults avg age 45, 70 with GI symptoms, 20 and 22 reporting milk and wheat intolerance respectively. There was no correlation between IgG or IgA antibodies or levels and type or severity of symptoms.
  • 82 patients were given either calorie-restricted diet or same amount of calories with IgG positive foods eliminated. Elimination group lost 5kg of fat and the control did not lose any.
  • Several major reviews in the last year has showed elimination of dairy, gluten, lactose, or FODMAPs leads to significant improvement in IBS. IgG testing can also improve symptoms, typically they will reveal antibodies to these commonly bothersome foods.
  • A comparison study found there was not significant correlation between IgG tests and foods that provoked symptoms upon re-introducing after an elimination diet in IBS patients

The problem with the positive studies is that following an IgG-guided elimination usually means that dairy and gluten are excluded, which gets people results. In research, this seems to happen regardless if one did food testing. Until we have tests that can pick up on many of the ways we react, a broad-based elimination diet will continue to be the gold standard.

For comprehensive, cost-effective support in implementing an elimination diet as well as other healthy lifestyle changes, join our online program. Feel comfortable and confident in your body as I give you step-by-step guidance

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BMC Gastroenterology. 2018 Jan 30;18(1):22.
Journal of Food and Nutrition Research, 2016, Vol. 4, No. 1, 1-5
Gastroenterol Clin North Am. 2018 Mar;47(1):107-137.
Curr Med Chem. 2017 Apr 27.
Gastroenterol Rep (Oxf). 2017 Feb;5(1):11-19.
Adv in Integrative Med. 2014 Dec; 1(3): 124–130.

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