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PART 2: How do food sensitivities develop and how do you know if you have them?

Last week I defined "food sensitivities" and hopefully clarified the difference between sensitivities, allergies, and intolerances. If you missed that post, it’s a good place to start. Today, I'll explain how food sensitivities develop, and how to know if you have them.

The list of symptoms and issues that can indicate food sensitivities is long and this is not a complete list. Here are some of the most common symptoms:

  • Digestive issues such as gas, bloating, constipation, diarrhea, acid reflux, feeling like there’s a lump in your throat, nausea, etc. These issues can range from mild discomfort after eating to serious IBS (irritable bowel syndrome).

  • Food cravings

  • Headaches of any type, including migraines.

  • Auto-immune issues

  • Skin issues. Eczema is the classic food sensitivity skin response, but any number of rashes or irritations can be connected to food sensitivities.

  • Fatigue

  • Excess mucus production (sinus congestion, post-nasal drip)

  • Pain and inflammation anywhere in the body

  • Allergies and asthma

  • Fibromyalgia

  • Brain fog

Does having one or more of these symptoms mean you have food sensitivities? Maybe. And it’s certainly worth further investigation to determine whether you do. I will explain the different ways to test for sensitivities in Part 3 of this series.

How does a food sensitivity lead to all these different symptoms? How does eating a particular food cause this crazy range of symptoms?


Here’s the basic process:

1. You eat the “offending” food.

2. Your immune system recognizes this food, perceives it as an invader that you need to be protected from, rather than as nutrients that need to be used by your body.

3. Your immune system mounts an attack against it by mobilizing white blood cells, antibodies and other immune components to protect you from the “invasion” of this offending food.

4. As part of this defense mechanism, your immune system releases mediators – histamine, prostaglandins, and cytokines primarily – to deal with the invader. I think of these mediators as your body’s "soldiers”.

5. In the course of protecting you from the offending food, the mediators cause damage in the form of inflammation specifically.

Inflammation = symptom. Where you experience the inflammation is going to be specific to you. Usually it’s in your constitutional weak point. For me, it’s usually my stomach and skin. For another, it might be chronically stuffy nose and insomnia.

This process is the same whether we’re talking about food sensitivities or true food allergies. Food intolerances work with a completely different mechanism.

Next question:

How does an innocuous substance such as food go from being healthy to dangerous?

What’s the REAL harm of eating a cashew, right? It’s not like eating rotten chicken filled with campylobacter, right?

The answer to this question is your digestion.

If your digestion is working correctly, your body breaks food down in multiple phases into its most basic components – microscopic nutrients that get absorbed into the bloodstream and lymph and distributed throughout the body.

Here’s a very basic explanation of the digestive process:

1. You break down your food mechanically (with your teeth) and mix it with enzymes in your saliva that begin chemically break down carbohydrates.

2. Your stomach “churns and burns” the food, mixing it in an extremely acidic environment with more enzymes to continue the breakdown process.

3. The food moves from the stomach to the small intestine where more enzymes continue the chemical breakdown of the food.

4. Your small intestine is lined with millions of villi and microvilli – a good analogy is a really thick and long shag carpet. The microvilli is permeable, but at the most microscopic level. When food is broken down into its smallest components, it passes through this permeable gut lining directly into your bloodstream, and your blood then transports it around your body to be assimilated into cells as energy.

5. Any leftovers, toxins or waste move through the small intestine into the colon or large intestine, and are excreted when you have a bowel movement.

So where do things go wrong?

Any digestive dysfunction cause be the root cause.

  • Maybe you aren't chewing well, so your food is not being properly broken down.

  • Perhaps you stomach isn't producing enough stomach acid (HcL) or digestive enzymes.

  • If the lining of the small intestine isn’t sound and the tight, microscopic junctions have opened up too much (this is commonly known as “leaky gut”), then particles of improperly digested food can pass directly into the bloodstream.

It doesn't matter whether it’s the healthiest, organic salad or McDonald’s happy meal. If it enters your bloodstream in an improper form, or too early, your body won’t recognize it as a nutrient for assimilation, but as an invader. And when the body encounters an invader, it mounts an immune response. That's what the immune system is for and we are so relieved when viruses and bacteria such as COVID 19 and E-coli are stopped in their tracks by this amazing system of ours.

The body recognizes and remembers all invaders, and this is how food sensitivities develop – something that is not only nourishing and delicious is now deemed dangerous and your body must defend itself from it. This is the most challenging part of food sensitivities for people to comprehend.

"But I thought ____________________ (fill in the blank) were good for you."

beets, avocados, etc.

This is true for the majority of us, just not for you, right now. It's disheartening and maybe disappointing, but the good news is, it's not a forever thing!

Next week, I’ll tell you how to determine which foods, if any, are causing reactions in your body, and explain my two-prong approach to addressing food sensitivities.

I appreciate questions and comments!

111 views2 comments


Sarina Collins
Sarina Collins
Apr 07, 2021

You're explanation of this is very easy to understand. Thank you!

Is there a reason why the immune system will suddenly react to a food that it never had a problem with before?

Apr 11, 2021
Replying to

Hi Sarina -

Thanks for your feedback. Your question is actually worth $6 million! There has been much research and discussion about this topic, and there's no definitive answer. Is it stress? Digestive dysfunction? Immune system just on overdrive and can't take the leaky gut anymore? All of the above? We know that zonulin which is released from gluten, is a major culprit of breaking down the intestinal barrier, but WHEN the immune system is going to decide that it's had enough is hard to determine or predict. If you know that certain foods cause problems for you (whether they are digestive or not), it's best to avoid them and seek help with restoring microbiome balance and improve digestive function.

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