Food Allergy Testing

Food allergies are incredibly common these days.  This is the first thing I think of when I see recurrent sinusitis or upper respiratory infections, asthma, ear infections, eczema, or psoriasis.  In addition to those, though, food allergies can also cause chronic gut issues (gas, bloating, IBS), fluid retention, autoimmunity, behavioral changes (lots of ADD/ADHD kids do much better when allergens are removed), and I’ve even seen cases where food sensitivities are responsible for hypertension and weight gain.

There’s a few theories:

1. Lack of beneficial flora (probiotics) in our diets.  Probiotics are important because they feed on the waste left over after we digest our food, and produce lactic acid, which helps protect our guts against pathogens.  We used to get plenty of them by eating raw and fermented foods... but these days, our food is so processed and overheated that there are precious few good flora left over.
2. Medicines that wipe out gut flora.  These include antibiotics, certainly, but they also include PPIs (such as omeprazole), nSAIDs (like ibuprofen), steroids (like prednisone), birth control, and many others.
3. Genetically Modified foods?  I put a question mark here because it’s not an established fact, but to me the evidence is strong enough that I avoid them and counsel my patients to do the same.  To read more on this issue, click here.
4. Anything causing inflammation in the gut.  This can be a bout of gastroenteritis, trauma, untreated malabsorption syndromes, environmental toxicity, and even chronic stress.  If there’s inflammation in the lining of the small intestines for any reason, it sets you up to develop sensitivities to foods you could otherwise consume with no problem.

Most people think of allergy testing as a skin-prick test, but this isn’t the test I prefer.  This is because skin-prick tests identify IgE antibodies only.  IgE antibodies cause immediate hypersensitivity reactions, and while this is very useful to know (it may keep you out of the hospital!), it will miss a good 90% of food sensitivities.  This is because most food sensitivities trigger IgG antibodies, which have a 72 hour window in the body.  This means you can eat something to which you are sensitive, and not react to it for a few days!

IgG testing is a blood test, and it’s never covered by insurance, unfortunately.  But for patients who aren’t able or willing to do the elimination diet (which is as cheap as your grocery bill, but it’s a pain), the blood test is definitely worth it.  The serum test I use also checks for IgE antibodies to foods at the same time.

If you have a hypersensitivity reaction that can send you to the hospital, then yes, you absolutely do!  And if you have Celiac disease, then yes, I’m afraid you’ll have to avoid gluten forever.

But for most patients who show up with IgG food sensitivities secondary to gut inflammation, stress, or low beneficial gut flora, it only takes about six weeks to heal up the gut lining.  During that time you’ll need to avoid the foods you’re sensitive to while we heal up your gut, but after that you can begin adding back most of the foods to which you were reactive – in moderate amounts.  (After six weeks, most people feel so much better that they have no desire to return to their previous diets anyway!)