The Difference Between Food Allergy, Intolerance and Food Sensitivity

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Have you always wondered? What’s the difference between a food allergy, a food sensitivity and a food intolerance? Knowing the difference can be the key to healing your health problems. Huge! Often these terms are used interchangeably, which is confusing.

Even GAPS Diet literature and well-respected functional medical doctors sometimes use the terms interchangeably. Most do not use allergy and sensitivity synonymously; but it’s very common to hear sensitivity and intolerance or intolerance and allergy used interchangeably. And yet they’re very different! Allergists know. Lab scientists know. Many naturopathic doctors use the terms correctly. Let’s define them here to be clear. Ultimately there is a rubric.

A food intolerance is sometimes confused with or mislabeled as a food allergy.  Food intolerances involve the digestive system. Food allergies involve the immune system. With a food allergy, even a microscopic amount of the food has the potential to lead to a serious or life-threatening reaction called anaphylaxis. (source)

I am not a doctor. Please consult your practitioner before beginning any new healthcare regime. No statement within this post is intended to diagnose or treat any health condition. This post contains affiliate links.

Food Allergy

Firstly, what is an allergic reaction?

It is known that white blood cells (also known as lymphocytes) are a fundamental component of the immune system that protects our bodies from invaders. When they make a mistake, an allergic response can occur. When a lymphocyte encounters a particle or cell and identifies it as a foreign invader, it produces antibodies specifically engineered to fight that particular threat. There are five basic types of antibodies, called immunoglobulins, or Igs. Each is classified by type with a letter suffix: IgA, IgD, IgE, IgG and IgM. The Ig known to be responsible for most allergic reactions to food is IgE, although IgG is also commonly mentioned. (source)

These foods are responsible for the majority of allergic reactions: cow’s milk, eggs, seafood, peanuts, soy, tree nuts, corn, citrus and wheat. (source) Most people know if they have a food allergy. If you see a doctor to get tested the IgE test is often preliminary to taking medication which prevents the release of histamines and other compounds. Common allergic responses include hives, trouble breathing, itchy eyes or nose, nasal congestion, sneezing and anaphylaxis.

(Non-food allergens can also be deduced by using the IgE test. These allergens include pollen, mold, dust mites, animal dander, medications like penicillin, insect venom from bee or wasp stings, cockroaches, and latex. [source])

Although most patients do not know which avenue to pursue, or even that natural healing is an option, it’s important to note that healing from allergies is possible. The magnitude of how is beyond the scope of this post, but diet is often a key role in healing. Eliminating the offending foods or environmental triggers is the first step. Beginning a gut healing protocol or using alternative healing methods with a skilled practitioner is the next step.

To name a few, alternative healing methods may include homeopathy, Traditional Chinese Medicine, urine therapy, and acupuncture. (When seeking healing for environmental allergies it’s noteworthy to keep in mind that allergies are often the result of an underlying food intolerance, [discussed below]).

In our family’s experience finding a capable practitioner who is skilled is the biggest challenge. Over the years we have received homeopathics from several doctors without the slightest effect. But when we found our current doctor he stopped my daughter’s allergic response while it was happening with homeopathics. (He then healed her by addressing her food intolerance, which I mention in greater detail below.) I have also heard wonderful firsthand stories of people being healed by their acupuncturist; however, I have never seen any results at all from acupuncture, personally. So finding the right practitioner is a good goal if food (or environmental) allergies are a complaint.

Food Sensitivity

The IgG and IgA tests look for antibodies that are different from those produced by a food allergy. When you have a food allergy, you have a direct and immediate response (after the initial IgE antibodies are produced). Food sensitivities are harder to determine because the body does not produce an antigen-antibody response.  IgG and IgA antibodies address long-term resistance to ongoing infections. Symptoms can occur hours or days later and range from headaches and nausea, to IBS and autism, to the development of various autoimmune diseases.

There are several approaches to determining one’s sensitivities. The ultimate goal in doing so is to reduce inflammation and to allow healing to happen. When it does, the foods can often be reintroduced successfully.

While the IgG test exists to help patients determine their food sensitivities it isn’t always accurate. Results vary from lab to lab and are not always reproducible. I don’t personally believe it’s the most helpful diagnostic test, nor is it often necessary. However, if you’re interested in this approach, Cyrex Labs gets great reviews as having the most consistent methods and results. (source) They’re a team of doctors and scientists who’ve improved over the years on their methods and understanding of how the tests work.  They recommend the comprehensive Array 10 and Array 3 testing to help your doctor determine your food sensitivities.

Another approach to determining one’s sensitivities (that’s free) is eliminating foods that are suspect for a period of time and then reintroducing them one by one, slowly, to watch for a return of symptoms (nasal congestion, itchy throat, phlegm, or digestive upset). This method is very effective as long as the patient reintroduces slowly, allowing at least one full week with each food. The temptation in reintroducing is to go too quickly, to feel so happy to have that food back that the patient doesn’t wait long enough to make sure they are symptom-free before recklessly adding back in another food and another. Ironically, patients often crave foods they are sensitive to and need to avoid.

Taken slowly, the Elimination Diet is a good method.

Let’s get back to the actual definition of a food sensitivity. It’s the most underused and missed term. When a doctor searches for which foods her patient should stop eating (to alleviate symptoms) she is most often talking about this category of foods: foods that a person is temporarily sensitive to due to underlying gut health issues. Food sensitivities are a result of both immune system reactivity and the digestive system. A breach in the gut lining, bacterial overgrowth, an infection, dysbiosis in the small intestine, low stomach acid can all cause an environment that allows small undigested food particles through the gut barrier. This causes an immune response.

So food sensitivities involve, therefore, removing the offending foods, because they’re causing an immune response and inflammation, and healing the gut lining to prevent the reaction in the future.

As an important side note, some patients need to utilize a rotation diet while avoiding offending foods. This prevents new food sensitivities from developing before the gut has had the time it needs to heal. (This was the case for me with juicing. I became sensitive to all the produce items I’d been juicing daily and could not eat raw produce for over a year, until I healed. I began juicing when I had an extremely leaky gut, not realizing the risk involved.)


Food Intolerance

The Carroll evaluation, that I have often written about in my posts, addresses the latter of the three reactions: food intolerances, which can become a hurdle to healing when not known. A food intolerance is about the body’s innate inability to digest a food. When someone says they are “lactose intolerant,” which used to be a pretty common complaint, they are using the term correctly. Their body lacks the enzyme lactase which is required to break down the lactose in milk. (This issue is a modern one, based on the advent of pasteurization. When milk is raw it already contains lactase, an is therefore self-digesting.) It is possible for someone to be allergic to milk, or to have a food sensitivity to dairy; but those are different issues.

Other examples of food intolerances? Read here about my daughter’s intolerance to dairy or mine to fruit. These are foods our bodies cannot digest. If one’s ability to detoxify is already compromised, eating a food intolerance causes gut dysbiosis and chronic irritation. Autoimmune diseases are born under these circumstances.

The man who developed the evaluation is named Dr. Otis Carroll, a naturopathic physician who practiced in Spokane, WA from 1917-1962:

…he determined that there were common categories of food intolerance. Most people tested intolerant to one of the following foods or food categories: milk, egg, meat, sugar, fruit, and potato. In addition, he discovered that most people had a problem with one or more combinations of food, similarly not well tolerated. The most common food combinations were these: grain and potato, grain with milk, grain with fruit, grain with sugar, fruit and sugar. Food intolerance is not limited to these categories, but most commonly a person we test will fall into one of these. There is also a need to look to other possibilities, such as soy, nuts, fish, etc. (source)

Emotionally, for both my daughter and me, giving up entire food groups was a process. We experimented just a bit after we found out which foods we were intolerant to, to make sure. For both of us the results were irrefutable. My daughter got asthma immediately when she ate only one bite of sauerkraut inoculated with whey. And my bladder symptoms and extreme fatigue return if I eat fruit.

Other patients may be more fortunate, and frankly, the longer we stay away from our offending foods the more we notice our body’s ability to handle small amounts. We never purposely give my daughter dairy, but it has happened accidentally. And the last time it did she had zero symptoms. This is because her gut has been able to heal more effectively without the offending dairy present and because the GAPS Diet has helped to heal her gut.

The-Difference-Food-Allergy-Intolerance-Food -Sensitivity

So, similar to a food sensitivity, if you remove the offending food and work on healing your gut, the body’s ability to process that food without alarm bells going off improves. However! most people should not return to eating their food intolerances if they wish to maintain good health. My doctor says that someone living in a sunny climate, who detoxes well and is in optimum health can eat their food intolerance without ever noticing compromised health. But for someone with a history of autoimmunity, it is likely unwise to try and reincorporate the offending foods, especially on a regular basis. Occasional “dabbling” will work for some well-healed patients.

What about patients who remove their food intolerances and never see an improvement of symptoms? My opinion, and my doctor’s, is that our blood is still revealing a truth to us. The Carroll evaluation can be re-done to confirm the results. But if the results are the same it is likely best to avoid that food if you have health issues. There may be insidious activity going on that isn’t seen. However, this patient may be safe having the food intolerance foods occasionally…just not on a regular basis. This is what my own judgment tells me. It’s a personal choice ultimately, as giving up food groups can be harder on some than on others. I think it’s best to find alternatives that you love, so the avoidance is easier.

Conclusion and Summary

It’s great to be aware of both one’s intolerances and one’s food sensitivities, so healing can happen.

Unlike food allergies and food sensitivities, it is not possible to remove one’s food intolerances.

  • A restricted diet that reflects one’s food allergies is essential, to avoid immediate and sometimes life-threatening immune responses, but may be temporary if the patient is able to find an alternative healing method that works.
  • A restricted diet that reflects one’s food sensitivities is temporary, assuming the patient avoids the foods and allows their gut to heal. Long-term removal of all processed foods from one’s diet is advised.
  • A restricted diet that reflects one’s food intolerances is permanent. This food, food group, or combination of foods should be avoided completely, unless the patient feels in optimum health, detoxes well and feels fine about occasionally eating these foods.
  • Finding one’s food intolerance(s) (and eliminating it/them) can help to heal allergies.

Last but not least, if you wish to find out your own food intolerances, you can order the kit in the mail through my doctor. (It’s $150 and I do not profit from the purchase.) I ask all my clients to have the evaluation done, as we have a lot more to work with by knowing this information. I was on the GAPS Diet for many years before I found out I couldn’t eat fruit. The results were a watershed epiphany that finally allowed my healing to project forward. I’m sorry to tailor a diet for anyone without them first knowing which foods to avoid so healing can happen.

Comments 25

  1. Thank you so much for writing this Megan. It can be so confusing to sort all of this out but this was very easy to read and understand!

  2. This is great! I have often tried to explain the differences to others, and now I’m happy to have an easy to read resource I can pass along!

  3. Hi Megan,
    I just had both a pap and annual physical and both doctors are unwilling to perform food sensitivity testing. I have chronic itching skin that baths or lotion can’t help. As well as, unexplained secondary infertility and I have had 3 twenty week stillbirths. I went to the page for your doctor but can’t figure out how to order the kit. I just want to be healthy .

    1. Hi Donnisha, I’m sorry for your struggles! It would be so nice if life offered more direct ways to get what we need, (and less pain!) Sending hugs. Okay, so when you go to Dr. Zeff’s page, go to the Contact page. CALL the office. That’s how you order the kit. They’ll mail it to you. You’ll mail it back. Then they’ll email you the information. Feel free to email me at that point or sooner if you want to consult via phone or Skype. I’d be happy to help with the itching skin issue and dietary guidance. You’re so wise to consider your diet with these issues. If you have any suspicions you can pull those foods out now. For example, dairy is notorious for causing skin issues. If you still have dairy in your diet, that would be the first food to consider pulling out. Best wishes!

  4. I’m probably reading too quickly, but is the kit you mention (from Salmon Creek Clinic) a blood test? Just wondering what exactly the the at-home test entails. Sorry if I read too quickly and missed it!

    1. Hi Jess, they do not call it a test; but it does include putting about 10 drops of your blood on a designated piece of paper, yes. 🙂 The kit includes a little blade (sorry, sounds awful, but it’s not) that helps us to poke ourselves.

  5. I’ve sent my dr. the link about the Carroll Evaluation. Such good stuff! And $150 to find out such life-changing information is so worth it! After finding out about my dairy and egg sensitivities today, I’ve had such a wave of emotions. From feeling “I can do this!” to “Oh, no, what am I going to eat?” to “But I have worked so hard on my gut!”… it’s been a rollercoaster of a day! As always, I’m grateful for your research!

  6. This was such a great article! I had the Carroll test done on my 4.5mo son because I thought it would be helpful to know which foods NOT to introduce to him. It came back that he is intolerant to meat, mined salt, and potato/grain combo. I find myself devastated that he is intolerant to meat. Do you think testing on such a young baby is accurate? Thank you for your insight!

    1. Hi Emily. Yes, so disappointing on the one hand. But on the other hand, I am SO happy for you to have this information! I believe it to be completely reliable; and imagine if you had fed him meat for years…! All the digestive issues and disease that would have occurred from such a young age. Instead you can focus on seafood, eggs and dairy! You can focus on all the foods he CAN have and also have peace about his diet. Knowing this information, inviting in this piece of the puzzle is hard, for sure. But for my life I always choose knowledge and health over ignorance and its result. Thank you for writing. May you have peace about the results and relative ease over the years implementing his diet with success. Much love. (Think of others, too, with THEIR challenges. Many food intolerances are not easy. I have kids who 1, can’t have dairy, 2, can’t have eggs and 3, me- who can’t have fruit. Making meals is challenging. But we do it, because it’s worth it!) Hugs.

  7. I’m learning more and more about this topic and appreciate this post, thanks! I’m curious… does anyone ever get a ‘no intolerances’ result with the Carroll test or is everyone intolerant to something it just varies as to what it is?

    1. From what I understand, everyone lacks enzymes to digest some foods. When someone is healthy and detoxing well the information is less imperative to have and apply. But everyone is intolerant to certain foods or food combinations, meaning their bodies do not digest that food well. It is only a deal-breaker/problem causer when they’re already struggling for their health in other ways as well. Then digestion is even more key to health and really matters for wellness. (Although for me, I’d want to know and apply the information no matter what, to bless my health and digestion even if I felt well and had seemingly great health.)

  8. I just received my results, and was told my intolerances are dairy and sugar. Is there a magical list of foods or recipes that one could use to narrow down what foods we can safely eat? Or at least some great suggestions?

    1. Post

      Hi Kelly, Did you get your results from Dr. Zeff with the “No” foods list? Do you have two primary food intolerances: dairy and sugar? What about your food combination intolerance? If your results are from Dr. Zeff, he does have lists of Yes foods for food products and restaurants.

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