Jul 01, 2024

Understanding Food Allergies, Sensitivities and Intolerances

Food Allergies

Food allergies. We are all pretty familiar with them. They are the reason peanut butter and jelly sandwiches have been banned at some schools. They are the reason people carry epi-pens with them to restaurants. They are the reason many people can’t enjoy some of their favorite foods. Food allergies can be dangerous, even deadly. And we often wonder about what other symptoms can be attributed to food allergies. Do food allergies cause weight gain or fatigue? What about nasal congestion or hair loss?

And, on a similar note, what about food sensitivities? And food intolerances? Are they dangerous? Are they different from food allergies? Can people die from them?

These are all good questions and the answers are fascinating. The simple answer is that food allergies and food sensitivities are completely different, and the difference lies not in the strength of the reaction to the food but in the way our immune systems respond to the food. Both trigger a reaction in our immune systems, but the pathways are completely different and therefore the outcomes are different. To understand the differences, it’s important to know that our immune systems make five different types of antibodies or immunoglobulins (IgA, IgM, IgD, IgG and IgE) depending on the specific threat it detects. When talking about reactions to foods, we will focus on the IgE antibodies (which are created in response to allergies) and IgG antibodies (which are the most common type of antibody and work to fight off and remember germs we have been exposed to).

It’s actually pretty fascinating to understand how complex and amazing our immune systems are! Even the top experts in immunity are learning new things all the time about the interactions and intricacies of this system. But, let’s focus here on understanding how our bodies react when we ingest something we are allergic to versus something we are sensitive to.

How Our Immune Systems React to Food Allergens

When we are allergic to something, be that a food, pollen, or a bee sting, at some point in our past, our immune system has tagged that substance as a foreign invader. We are not exactly sure how this tagging happens, but it seems to be a combination of our genes plus exposure to the offending substance at a time when our immune systems are already stressed.

Once our immune system “tags” something as a foreign invader, it remembers that substance forever and will identify it and attack it whenever it is present. Now, this is fabulous when it comes to bacteria, viruses, parasites, cancer cells, and other things that destroy our health. It’s not so great when our immune system attacks something as innocuous as the protein from a peanut. But, nonetheless, our immune system does what it is designed to do. It remembers the “invader” and jumps into action to protect us.

As I said before, our immune systems are complex with many different types of cells, antibodies and enzymes that all interact in miraculous ways to mount several different types of defenses against invaders. But, in the case of food allergies, because our immune system has already identified this substance as an invader, it is primed to react to it quickly. It does this by making IgE antibodies specific to this invader. Now these IgE antibodies don’t just attack the invader. They actually bind with mast cells that are always waiting under exposed surfaces of our bodies. Mast cells are our first line of defense against anything that penetrates our natural barriers. They hang out under our skin and mucosa linings (nose, mouth, eyes) waiting for something to penetrate so they can attack. And, these mast cells are filled with granules, which are different chemicals that kill foreign substances. One of these chemicals is histamine.

So, the IgE antibodies with the allergen encoded as the target now travel to the site of the mast cells (under the skin and in the mucosal areas) and bind with the mast cells. Here they wait and accumulate. When the immune system deems that there are enough mast cells activated to fight off this invader, there is a signaling event that starts the release of the granules (including histamine) from the mast cells. It’s like an ambush - tons of these granules (histamine included) are released into the skin and mucosa linings all at once. Now, histamine increases capillary permeability which allows fluid to escape from the capillaries into the tissues. What does this lead to? It leads to many of the symptoms we associate with allergies like watery eyes, runny nose, sneezing and hives (inflammation under the skin from the released fluid). While this is uncomfortable, it is not necessarily dangerous. The danger comes about by another impact of the histamine - it can cause the smooth muscles in our bodies to contract. Smooth muscles are the muscles that form the walls of our hollow organs like our intestines, blood vessels and throat. When the histamine causes these muscles to contract involuntarily, especially in the airway, it can make it difficult to breathe. This is why people with allergic reactions often have a hard time breathing and need immediate medical attention.

Can Food Allergies Cause Weight Gain or Fatigue?

Now that we have a better understanding of what is going on in our bodies when we have a food allergy, we can answer some of those questions from the start of this blog.

Food allergies do not cause weight gain.

Can Food Allergies Cause Nasal Congestion?

As a result of a food allergy, we can often experience nasal congestion when the histamine is released into the mucous membrane of our noses.

The body’s intense reaction an ramping up of the immune system in response to a food allergen can indeed cause fatigue.

Can Food Allergies Cause Hair Loss?

Food allergies do not directly lead to hair loss. However, food allergies can cause nutrient deficiencies which can, in turn, lead to hair loss.

When treating allergic reactions, there are two routes we can take, depending on the severity of the reaction. If we are having a severe reaction that includes the contraction of the smooth muscles in our throat, we will need a shot of epinephrine (usually administered through an epi-pen). This relaxes those muscles, opens the airways, and diverts the blood (and therefore the immune cells) away from the skin.

For more mild reactions, we typically take an antihistamine. These medications work to reduce or block the histamines that are released in our systems.

Because our immune systems have such an immediate and obvious reaction to an allergen, we learn pretty quickly to avoid those substances whenever possible.

Food Sensitivities

Now, food sensitivities are different. They activate a completely different pathway in our immune systems and are much harder to identify. Again, we are not sure how we develop sensitivities to different substances, but we do know that our bodies’ reactions involve the IgG antibody (as opposed to the IgE antibody with allergies) which is released in response to something our body recognizes as a threat (germ, bacteria, etc). The IgG antibody is the most abundant in our immune system. It is found in the blood and fluids outside of cells and is called into action for a huge array of infections and illnesses. In short, when there is something amiss in our bodies (other than allergies when the IgE antibodies are in charge), IgG antibodies are called into action.

So, when we are trying to understand food sensitivities, it is important to know that this antibody is called into action when someone has a leaky gut. In this situation, undigested food particles are getting through the intestinal wall and into the bloodstream. Our bodies don’t recognize the protein chains of undigested foods and, therefore, launch an attack that includes the release of IgG antibodies. This results in inflammation in the intestine and throughout the body.

When we have inflammation in our intestines and throughout our bodies, we often experience symptoms as varied as gas, bloating, distended bellies, congestion, sinus issues, migraines, brain fog, mood swings, decreased energy, joint pains, weight loss problems, eczema and asthma. As you can imagine, with such a wide variety of symptoms, it can be really hard to pinpoint the food or substance that is triggering the release of the IgG antibodies.

To make matters more complicated, these symptoms can take hours or even days to show up!

And, because we aren’t aware that we have a sensitivity to a certain food, we continue to eat it. Once eaten, the food stays in our digestive tract for 3-4 days which means that our bodies are reacting to it that whole time. Additionally, when we release IgG antibodies, we also release cortisol. Under these circumstances, the cortisol acts as part of the control system of the immune response. But, when we have cortisol in our systems, we typically feel a surge of energy, well-being and mental sharpness. So, when the offending food is out of our system, the immune system relaxes, the flood of cortisol goes down and we typically feel worse. This leads us to return to eating the food that makes us feel “better” in the short run. Can you see how tricky this can be to figure out?

While there are tests available that show the level of different antibodies in our systems, these do not show which foods we are sensitive to. The best way to determine this is to remove the top offenders from our diets for 3-4 weeks and then slowly reintroduce them one by one, keeping a diary of your body’s reactions. The top offenders are corn, eggs, dairy, soy, sugar, gluten and yeast. This takes dedication and is not easy to do, which is another reason food sensitivities are difficult to assess and treat.

Food Intolerances

Lastly, we have food intolerances. Again, these are different from allergies and sensitivities. Food intolerances are not caused by an immune response but are related to a deficiency in a particular enzyme that the body uses to break down food. For example, someone whose body does not produce lactase is not able to properly process lactose. This leads to uncomfortable symptoms like gas, bloating, indigestion, nausea and diarrhea but is not a serious threat to our health. So, even though the symptoms can look a lot like food sensitivities, the mechanism that leads to the symptoms is completely different.

I don’t know about you, but I am impressed by what my immune system can do! It is there, constantly on the lookout for dangers, quick to attack when it spots one, and then remembering that threat so it can more efficiently respond the next time it senses it. It is an amazing system!

Unfortunately, when it comes to allergies, our immune system gets some things wrong. But, at least it gives us concrete information that we can use to avoid the offending substances. Otherwise, it is an incredible system that we want to provide with all it needs to defend us. To support your immune system, be sure you are eating plenty of foods rich in Vitamin C, Vitamin D, zinc, selenium, iron and protein!