Food Can be Healing or Detrimental To Health - Do you know which foods are which?

Sometimes food reactions are not obvious.  When we eat we are bringing the outside world into the body under the watchful eye of the immune system.  This is a survival mechanism.  Your immune system is present in the gut to protect you- so what is the problem? 

In the modern food environment food is not just food.  Our immune system now has to deal with pesticides and herbicides that enter the food supply from farming.  There are food additives and preservatives and alterations of the food with processing to the point that sometimes the immune system is reacting to these things and linking them with the food. 

The issue becomes a chronic low level activation that can be detrimental to overall health and contributing to chronic immune activity.  Which in the brain can result in mood changes, in the gut can manifest as digestive symptoms.  It can even be part of autoimmunity where the body turns on itself and attacks its own tissue. 

How do you know which foods are feeding the fire?

The gold standard for figuring it out is an elimination diet with re-introduction.  Because the half life of the immune response to a food is about 3 weeks, it takes removing the suspect food for about 3 weeks and then adding it back to then assess symptoms.  There are common foods that are more likely to contribute to food reaction.  Most of them are either hard to digest or immunologically more likely.  Those foods tend to be the ones we remove when we do a classic elimination diet.  They are foods that you probably have heard sometimes being an issue such as gluten from wheat and dairy. 

Sometimes it is hard to figure things out even with an elimination diet.  In those circumstances, we often use blood tests that look for immune reactivity from the immune system.  We are NOT talking about an “allergic reaction” which is often the IgE “branch” of the immune system that results in classic allergy symptoms from itching and hives all the way to anaphylaxis which can be life threatening.  We are talking about IgG or IgA reactions which are more subtle reactions and you may not realize are part of chronic inflammation for your body.  These are often termed “non-IgE food reactions” or food sensitivities.  If you are sensitive to a food, eliminating it for a period of time can be beneficial.  It also does not mean you can NEVER eat that food again.  It does however mean that it is worth looking into and seeing if taking it away and then reintroducing it is helpful.  Often removing an offending food is the difference between finally “healing” what we call increased intestinal permeability or leaky gut – or not. 

Aside from IgG and IgA  reactions, there are other non- IgE reactions that could occur including reactions involving eosinophils (as in Eosinophilic Esophagitis) which is a specific type of cell in the immune system.  There are also reactions involving an issue breaking down food components (for example lactose intolerance).  To keep it simple we are only going to be discussing evidence for IgG reaction in this article which is often more subtle and less obvious.

What types of problems could be related to IgG reaction foods?

There is specific literature and the clinical observation that a diversity of symptoms and diagnoses could be influenced by addressing IgG food reaction specifically. 

Irritable Bowel Syndrome and Reflux – When other diagnoses have been excluded and we are left with digestive unexplained symptoms that are often lumped into Irritable Bowel Syndrome or “IBS”.  Sometimes food reaction evaluation can be helpful in supporting the gut epithelium and the gut microbiome and immune reactivity or inflammation. 

Migraine Headaches – Here too where IgG is a systemic antibody in the immune system, affecting the vascular system and migraines which are thought to be vascular related  headaches can be improved by a modified elimination of reactive foods. 

Autoimmune Disorders-  There is a lot of observational and anecdotal evidence that autoimmune conditions sometimes respond to elimination diets.  Some of these dietary interventions can be quite strict and eliminate many foods.  It is helpful to do testing in that circumstance as it is impossible and really not recommended to remove variety from the diet.  IgG food sensitivity testing can play a big role here. 

Skin Reactions / Atopic Dermatitis-  If IgE testing has been done and has not been helpful, it could be useful to look at other types of reactions and how they can relate to skin symptoms.  This is one where often the health of the gut and the microbiome may be playing a role and while it may not entirely be food reaction alone, removing offending IgG reactive foods for a period of time allows for the gut-immune response to quiet down and skin reactions can improve in intensity and severity.

Psychiatric Disorders- There are not as many studies on psychiatric disorders and food reaction.  However, in the current hypothesis that mental health problems are related in part to inflammation in the brain it is worth considering IgG food reaction for depression and anxiety.  There are more studies on depression and correlation between IgG and LPS (Lipopolysaccharide) produced by gut bacteria and severity of symptoms.  Of course correlation does not equal causation but I have found looking at food reactions helpful sometimes for depression and anxiety.

Obesity / Weight Management-  This is another one that may be off the radar for most people.  There are studies suggesting a correlation between obesity and IgG food reactivity- again caution here as correlation is not causation.  It does mean though if we can identify food reactions and address this, inflammation may improve.  Removing reactive foods alone likely would not result in weight loss.  I do think that in the setting of weight loss resistance, we are more likely to see reduction in weight in response to lifestyle changes if we address food reaction.

There is a simple blood test that we offer at Sparkle that is reasonably priced and can be done at home.  If you are struggling with figuring out which foods are worth removing from your diet for a period of time – this type of test is helpful.  The test also includes more than just the “usual suspects” like gluten and dairy.  It includes foods you may not realize are factoring into your chronic inflammation that you eat on a regular basis.

The main criticism of these tests is that it can lead to unnecessary elimination of foods.  I think that is important when evaluating these results we treat them as a guide and reactions can evolve over time.  If you have had a test several years ago, it may be time for a refresh to see what your immune system is currently up to!

References:

Garmendia JV, De Sanctis JB, García AH. Food-Specific IgG Antibodies: Decoding Their Dual Role in Immune Tolerance and Food Intolerance. Immuno. 2025; 5(3):25.

Spergel JM. Nonimmunoglobulin e-mediated immune reactions to foods. Allergy Asthma Clin Immunol. 2006 Jun 15;2(2):78-85.

​​Singh P, Chey WD, Takakura W, Cash BD, Lacy BE, Quigley EMM, Randall CW, Lembo A. A Novel, IBS-Specific IgG ELISA-Based Elimination Diet in Irritable Bowel Syndrome: A Randomized, Sham-Controlled Trial. Gastroenterology. 2025 Jun;168(6):1128-1136.