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8 Hidden Food Sensitivities You Might Not Know You Have (And How To Find Them)

William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner By William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner
Will Cole, IFMCP, DNM, D.C., is a leading functional medicine practitioner with a certification in natural medicine and a doctor of chiropractic degree.
8 Hidden Food Sensitivities You Might Not Know You Have (And How To Find Them)

William Cole, DC, a functional medicine practitioner, is an expert at identifying the underlying factors of chronic conditions. Join Dr. Cole for an exclusive webinar on May 24, 2016, and learn how to uncover your food intolerances, heal your gut, and feel your best again. Check out his mindbodygreen course, The Elimination Diet: A 60-Day Protocol to Uncover Food Intolerances, Heal the Gut, and Feel Amazing.

When it comes to chronic health problems, I believe that the foods we eat are some of the biggest pieces of the puzzle. After all, food is medicine: Our bodies are alive because of brilliant biochemistry, and the foods we eat will either help feed health or disease.

Most people know to avoid sugar and junk food, but beyond that, I believe we're all different. I have seen the healthiest foods flare up one person, contributing to inflammation in their muscles and joints, digestive problems, and brain fog, among other symptoms. But that same food can also be a great food medicine for the next person.

What's going on? Well, it can be one of three things:

Food allergies: These involve the immune system and are the more immediate and more severe response. Symptoms of an allergic reaction can include rashes, itching, hives, and swelling, or even anaphylaxis, which involves serious difficulty breathing and can be fatal.

Food intolerances: Unlike allergies, these do not directly involve the immune system. Instead, intolerances occur when your body is unable to digest certain foods (such as dairy) or when your digestive system becomes irritated by them. These are usually the result of enzyme deficiencies.

Food sensitivities: These are similar to intolerances, but it's often less clear why someone reacts poorly to a certain food. Food sensitivities also may result in a more delayed reaction, and you might be able to digest a small amount of the food without issues.

The symptoms for intolerances and sensitivities might include:

  • Bloating
  • Migraines
  • Runny nose
  • Brain fog
  • Inflammation
  • Flu-like symptoms
  • Stomachache
  • Irritable bowel syndrome

Here are the foods that I find most commonly cause problems:


1. Gluten-containing grains: wheat, rye, barley

Gluten, the protein that's found in grains like wheat, rye, and barley, is probably one of the most common food intolerances and sensitivities that I see.

While most of us have heard of celiac disease, the reality is that celiac disease is the end stage of a whole autoimmune spectrum of gluten sensitivity and intolerance. In other words, there can also be less serious reactions to gluten. If you believe you might have a sensitivity to gluten, there are some tests you can consider, but this is also an area where the elimination diet can be helpful.

2. Gluten-free grains: corn, rice, buckwheat

Many of you who are reading this are health conscious, and some of you probably already avoid gluten. But if you've gone gluten-free and still have symptoms, gluten-free grains could also be a potential problem.

There are two possible ways you could be sensitive to gluten-free grains. One is a regular sensitivity, like anything else. A second, often overlooked area of food intolerance is cross-reactivity. The proteins in grains such as rice and corn can be similar enough in structure to gluten, and it can cross-react as gluten, a theory called molecular mimicry. It's sort of like a case of mistaken identity.

Many of my patients have sensitivities to some gluten-free grains, although not all.

3. Nightshades

Nightshades are a plant group that consists of tomatoes, peppers, potatoes, eggplant, goji berries, and some spices containing alkaloids, which can be inflammatory for some people.


4. Legumes

Legumes include all types of beans (kidney, garbanzo, black, fava), lentils, peanuts, edamame, and soy products (tofu, miso).

Many of these foods are staples for people who are trying to eat more plant-based, with great intentions. But the lectins and phytate proteins of legumes can be hard for some people to digest. The carbohydrates are also yummy food for your gut bacteria, releasing gas as they consume the legume starches.

Even if you don't get gas from legumes, they could cause undue stress to your gastrointestinal and immune system. Peanuts might also contain aflatoxin (toxins produced by a mold) while soy has phytoestrogens. I've found that out of all the legumes, these two foods typically cause the most issues for people.

5. Eggs

The incredible egg has many nutrients, mainly in the yolk—but it can be an issue for some people.

I find that it's actually the egg white that is typically more immunoreactive for people. The protein in the white, albumin, could pass through the intestinal lining if you have leaky gut syndrome, contributing to inflammation.

The yolks are generally better tolerated. Although it's important to note that some people can't even handle the yolk.



This strange sounding acronym stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. In short: fermentable sugars. These short-chain sugars are not fully digested in your gut and can be excessively fermented by your gut bacteria.

This fermentation releases hydrogen gas that could lead to distension of the intestines—which can cause major IBS symptoms in some people like pain, gas, bloating, constipation, and diarrhea. This would be considered a FODMAP intolerance, mainly due to functional issues like small intestinal bacterial overgrowth (SIBO).

Most of the high-FODMAP foods are actually healthy, real foods. But even when it comes to natural foods, what works for one person may not be right for everyone. Here are the foods that should be avoided or severely limited if you have IBS symptoms while you heal your gut:


Artichokes, asparagus, beetroot, celery, garlic, onions, leek bulb, legumes, pulses, Savoy cabbage, sugar snap peas, sweet corn


Apples, mango, nectarines, peaches, pears, plums, watermelon


Milk, cream, custard, ice cream, soft cheeses, yogurt


Rye, wheat-containing breads, cereals, crackers, pasta


Cashews, pistachios

Fructose, one FODMAP sugar, is one of the more common intolerances. Fructose intolerance is often found in people with recurring stomach pain and bloating.

The goal with treating a FODMAP intolerance is not to remove the foods forever but to heal the gut so that you can eventually increase your intake of these foods, especially the high-FODMAP fruits and vegetables.

7. Dairy

Casein, the protein found in dairy, is another common sensitivity.

On top of this, cows on most major dairy farms are given hormones and antibiotics, live in unhealthy conditions, and are fed corn instead of grass. Their milk is then typically pasteurized and homogenized and the fat is removed. To make up for it having little nutrition, synthetic vitamins are injected into the milk, trying to simulate what nature had already included in the whole-food form.

I find that fermented dairy, such as grass-fed kefir and yogurt, mitigates some of the problems people have with casein sensitivity so is usually better tolerated. They also offer beneficial bacteria for the microbiome.


8. Nuts and seeds

The roughage of nuts, as well as the protein lectins and phytates, can irritate some people.

Plus, most nuts sold in stores are typically coated in inflammatory industrial seed oils, like soybean or canola oil. They could also contain partially hydrogenated trans-fats, which can contribute to problems as well.

I find that people who are intolerant to nuts typically do better buying them raw, lightly toasting them at home, and enjoying them sparingly.

How to discover your food sensitivities:

There are many labs I run to help pinpoint which foods might be causing someone issues. But you can also find out which foods aren't working for your body on your own by following the elimination diet.

In my video course with mindbodygreen, I'll teach you exactly how to use the elimination diet. By temporarily removing the foods that are most likely to cause reactions, you'll give your gut time to heal and help bring down inflammation levels.

Then, when you bring those foods back in systematically, you'll be able to see which foods your body loves and which ones it has trouble with. By doing the elimination diet myself, I found that I couldn't tolerate certain sugars, dairy, and gluten. What foods are not working for you?

William Cole, IFMCP, DNM, D.C.
William Cole, IFMCP, DNM, D.C.
Will Cole, IFMCP, DNM, D.C., is a leading functional medicine expert who consults people around the...
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More from the author:
Uncover Hidden Food Intolerances That Wreak Havoc On Your Gut
Check out The Elimination Diet
Regain your energy, vitality and health by tapping into the power of the Elimination Diet with this practical and effective nutrition course.
William Cole, IFMCP, DNM, D.C.
William Cole, IFMCP, DNM, D.C.
Will Cole, IFMCP, DNM, D.C., is a leading functional medicine expert...
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