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Food Allergy vs. Food Intolerance — And What to Do About It

by Stephanie Margolis, R.D.

Food intolerances affect approximately 20% of the population and you have probably seen over-the-counter tests to help you know if you are in that 20%. But how do you know if you need to worry about your digestion and should get tested?

Do You Have an Allergy or Intolerance?

There is a lot that goes into this terminology and the meaning matters! If you have a food allergy, you will have an immune response to a certain food or food component. Much like any allergic response, your immune system detects the additive or nutrient and kicks into overdrive. This can look like: hives, wheezing or shortness of breath, tingling of tongue, abdominal pain, diarrhea, or swelling. Food allergies are typically easy to identify and an allergist can really nail down what is causing your reaction. Cow’s milk, eggs, soy, tree nuts, peanuts, and fish/seafood top the list as the most common foods to cause an allergic reaction.

Food intolerances are totally different and don’t cause an immune response. A food intolerance is simply an abnormal reaction to food. It may look like bloating, gas, stomach pain, diarrhea, constipation, acid reflux, rashes, chronic runny nose, fatigue, and headaches. Another major difference between a food allergy and intolerance is that when you have an intolerance you may be able to tolerate the food in small amounts and be fine; however, if you are allergic even having trace amounts of the food can cause a strong reaction.

There are many reasons you may be intolerant — and why you may become intolerant after being fine for years. The first may be pharmacological reasons, such as starting a new medication that is interacting with a food or enzyme in your body. Second, it could be an enzyme deficiency, meaning your body doesn’t have something it needs to help digest the food. Finally, it could be an unknown GI issue.

What to Do If You Suspect Food Intolerance

Yup, I definitely have a food intolerance … but to what? The list of common “intolerance foods” is LONG — honestly, you can be intolerant of just about anything. Also being intolerant to a certain food doesn’t mean you may be intolerant of all the foods in that group.

For example, FODMAPs are a well-studied group of foods that have clinical guidelines for interventions. However, the thing tying the FODMAPs together aren’t food groups (e.g., fruits, dairy, gluten, etc.) but are components foods have in common, such as excessive fructans, lactose, polyols, and galacto-oligosaccharides. Have I lost ya? So in easier words … If you have trouble with wheat, onion, garlic, avocados, pears, milk, legumes, or apples then you may be sensitive to the FODMAPs. If this is true, then there are FODMAP diet resources in abundance that can guide you in that right direction.

If the only thing that stuck out to you on that list was wheat, then it is possible that you are gluten intolerant. (Bear in mind, gluten intolerance is not the same as celiac disease, which is an autoimmune condition.) If this is the case, you may have mild GI distress with gluten but also find yourself with brain fog and fatigue. If this is you then you would exclude or limit foods like bread, baked goods, pastas, cereals, crackers, beer, gravies, and soups.

Another broad group of foods that often cause intolerances are food additives and food chemicals. While they get talked about a lot, sensitivities to these foods are only present in 0.01 – 0.23% of the adult population. Below are some additives/chemicals and the foods they belong to:

  • Amines: found in cheese, chocolate, bananas, ham, and fish
  • Glutamate: found in tomatoes
  • Food colors: found in too many foods to list here 🙂
  • MSG: found in canned foods and soups, fast food (especially common in Chinese foods), seasoning blends, and chips/snack foods
  • Nitrates: found in ham, deli meats, hot dogs, and bacon
  • Sorbic acid: found in processed cheese slices

You can probably see that the link here is more processed foods, except for amines and glutamate which are natural food chemicals.

Should I Take a Food Sensitivity Test?

This is all starting to sound familiar and you’re wondering “Can’t I just take one of those tests and solve my dilemma?” Short answer -— yes, you could. Should you? Eh, let’s talk more. The common home tests that you see online or in stores  are new and the evidence behind them is lacking support. If you take one of these tests, it is very likely you will get a positive result. However, false positives are very common and it’s partly because they use the presence of IgG to detect an intolerance. IgG is the antibody immunoglobulin G. This is an antibody which could indicate your body is not tolerating the food. BUT IgG is also a memory antibody and may not be specific to a person’s sensitivities. According to research, any time you eat your body will produce IgG, the more you eat a specific food the more IgG to that food that will be produced. SO you can see how it gets murky.

Getting to the Root of Your Digestive Issues

First look at your behaviors to identify any other reasons you may be having digestion issues. These could include:

  • Eating too quickly: Extra air you gulp down can lead to bloating, cramping, and gas.
  • Too much fiber too fast: Many times when you have diarrhea or constipation, you will try to treat it by increasing your fiber. This isn’t a bad thing, but do it slowly and drink tons of water to help move your food through.
  • Not enough fluids: Fiber aside, if you aren’t drinking enough water, or non-caffeinated drinks, you can be slowing your GI tract down.
  • Gut flora imbalances: If you’ve been on antibiotics or lack yogurt or fermented foods in your diet, you may have imbalance in your gut flora, and therefore your gut isn’t loving any foods you choose.
  • Stress or lack of sleep: If you aren’t giving your body rest, it is harder for it to work optimally for you.

There are many steps you can take to improve your gut health. If you still think you have a food intolerance, you can try an elimination diet. Or make an appointment with your MD to discuss. Before you go in, keep a detailed journal of food you eat, timing of meals, and timing of symptoms to help them identify commonalities and determine next best steps.