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Are there certain foods that make you feel sick? Do you know someone who’s had a bad reaction to food? Maybe you’ve just heard all the buzz about food allergies, intolerances, and sensitivities, but do you know what they really mean?

Many people use these terms interchangeably to describe an adverse or abnormal reaction to food, but scientifically these terms mean very different things. They do share the commonality of an unfavorable reaction to food, but they are all caused by separate triggers.

What’s a food allergy?

food allergy is abnormal, life-threatening reaction to food triggered by your immune system. The symptoms of an allergy include itching and swelling of the mouth, abdominal cramping, vomiting, diarrhea, hives (a skin rash), difficulty breathing, and the closing of the throat or airway. Depending on the severity of the food allergy, you may have to avoid eating it, touching it, or being in a room with it altogether because your life depends on it.

If you have a true food allergy, you probably know about it and carry an Epi pen with you in case of emergencies. Allergic reactions tend to be immediate and severe, often triggered by the IgE antibodies in your bloodstream. The most common food allergens include:

  • peanuts
  • tree nuts
  • milk
  • dairy
  • egg
  • wheat
  • soy
  • fish
  • shellfish

There are, of course, plenty more foods that can trigger an allergic reaction. Some people have cross-reactive food allergies to fruits and vegetables because those foods contain proteins that are structurally similar to certain environmental allergens, like birch, ragweed and mugwort pollen.

*NOTE: At this time, the only present conditions associated with gluten include celiac disease, wheat allergy, and non-celiac gluten sensitivity. A gluten allergy is not a real condition, nor is it recognized by the American College of Allergy, Asthma and Immunology. This is not to say that gluten cannot cause problems for you, but rather that your reaction to gluten is not classified as an allergy. If you have an issue with gluten, then it is either a sensitivity or celiac disease.

What’s an intolerance?

If you have a food intolerance, then you will still have an abnormal reaction to a food, but it won’t be because of your immune system; it will be an issue with digestion. An intolerance, like lactose intolerance, is actually a sign that your body is lacking a specific enzyme. [Enzymes are the tiny chemical-reaction machines that allow your cells to build things or break them down as they please.]

So, if you have a lactose intolerance, then that means that you lack the enzyme lactase. If you consume too much lactose (the sugar found in cow’s milk) without enough specific enzymes, then those undigested sugars pass into your small intestine and cause problems. Imagine what would happen if you tried to swallow an entire burger (or veggie burger) in one bite without chewing it first. You would likely choke, possibly gag, and if you couldn’t spit it out, you’d be understandably pissed for a while.

And that’s exactly what happens when you have an intolerance. You can eat a food, but your body can’t break it down properly into tiny pieces, so the large molecules pass through your digestive tract causing problems like bloating, gas, abdominal cramping, diarrhea, or vomiting. If you have an intolerance of any kind, the best way to alleviate symptoms is to consume supplemental enzymes or avoid aggravating foods.

What’s a sensitivity?

Now, if you don’t technically have any food allergies or intolerances, then you most likely have a food sensitivity. A food sensitivity is abnormal reaction to food triggered by your immune system, specifically your IgG antibodies. Unlike an allergy, a food sensitivity is not life-threatening, the symptoms are often inconsistent and difficult to reproduce, and reactions tend to be subtle and delayed – sometimes for up to 72 hours.

Potential trigger foods can include beef, citrus fruits, corn, dairy, eggs, eggplant, gluten, grains, legumes, potatoes, tomatoes, peanuts, peppers, pork, soy, yeast, and more. Symptoms can include fatigue, bloating, headaches, mood swings, abdominal cramps, acne, eczema, rosacea, and more. If you suspect that you have a food sensitivity, the best course of action would be an elimination diet test.

If you suspect a food is causing problems for you:

  1. Write down all your current symptoms with levels of severity
  2. Remove the suspected food from your diet for 2 weeks
  3. Take note of how you feel
  4. Reassess symptoms and severity
  5. Reintroduce the food back into your diet 3 times a day
  6. Do this for 3 days total
  7. Take note of any changes in symptoms

If you felt better without that food, then consider removing it from your diet for 4-6 months. If you didn’t notice a difference at all, then add it back into your diet. An extended elimination diet is one of the best ways to determine the best customized diet for you, but I’ll dedicate an entire post to that topic in the next few weeks. Stay tuned!


The moral of this story is that food can be healing or harmful to people in a variety of ways. Definitions are constantly changing as more and more research emerges on these topics, but this is a general picture of the ways that your body can react negatively toward food. Do you fall into one of these categories? If so, which one?


  • Shelley says:

    Thanks for this great blog! I’ve been scouring the web for ages looking for just this type of specific info! I suffer from IBS, Endometreosis and food sensitivities/intolerances (don’t know which)…I’m working on nailing down specific foods which aggravate me, but it’s really hard when there’s other factors at play. Climbing on no grains was nigh on impossible, but now I’ve learned that sourdough is ok in small doses, and also spelt flour seems to sit ok. No other grains work though – especially rice.

  • Aicacia says:

    Hi Shelley! I’ve heard that about sourdough actually! I’m glad you’ve been able to find a few foods that you can tolerate well. Shoot me an email at I would love to see how I can help!

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