It can seem strange at first to think that something you have been eating your entire life may be making you sick. This is especially true when you had a few (if any) symptoms when you were younger. Food sensitivity is a relatively new concept that the medical community has only recently begun to recognize. We are constantly learning more about how it happens and what possible causes may be.

What Are Food Sensitivities?

It is important to distinguish between food allergy, food sensitivity, and food intolerance. Although often used interchangeably, each condition involves a different process in the body. So what is the difference between them? 

A food allergy is triggered by an extreme immune response, mediated by the IgE type of antibody. This allergic response can escalate to anaphylaxis. Anaphylaxis is a severe allergic reaction. It requires emergency treatment due to restricted breathing and blood pressure drop.

Food intolerance is the inability to properly digest food due to a lack of digestive enzymes. The most common example of food intolerance is lactose intolerance. Individuals lack the lactase enzyme required to digest lactose in dairy products.

Finally, food sensitivity is a term that represents a spectrum of other (non-IgE) immune reactions triggered by the presence of certain foods in the digestive tract. Because “food sensitivity” is still a bit of an umbrella term, it is difficult to completely define its boundaries. The most common immmune response associated with food sensitivity is an IgG reaction. IgG is a G-type antibody. Some recent research also associates food sensitivity with IgA antibodies. Growing evidence shows that sensitized individuals exposed to certain food proteins develop erratic immune responses. Some responses can even trigger autoimmune disease. One severe example of this is the gluten sensitivity associated with celiac.

What Causes Food Sensitivity?

Researchers have not yet identified the exact cause of food sensitivities. Current theories suggest that reduced gut integrity and limited parasite exposure may contribute. According to the hygiene hypothesis, regular exposure to microbes and parasites helps regulate the immune system. The development of sterile home conditions, antimicrobial products, and strict cleanliness has phased out this exposure in children. Some researchers believe the parasite-fighting immune response may overreact to harmless food proteins without regular stimulation. It is possible that these two potential causes both play a role.

Immune System in the Gut

The digestive tract plays a large role in the health of our immune system, with over 70% of our body’s immune cells lining the inside of it. When a food sensitivity occurs, the immune cells in our gut respond as if the food is an invader due to their over-sensitivity to that particular product. The immune system is composed of many different immune cells as well as immune messenger molecules, called cytokines. Because of this variety, the inflammation caused from a food sensitivity can show symptoms in distant and seemingly unrelated parts of the body. See the symptoms paragraph for more information.

What Are The Symptoms of Food Sensitivities?

Food sensitivity can cause a wide variety of symptoms in the body, which often makes it difficult to diagnose at first blush. Food sensitivities can cause a wide range of symptoms because they involve complex immune system responses. Digestive symptoms commonly include gas, bloating, poor digestion, nutrient malabsorption, diarrhea, constipation, mucus, and acid reflux. Some of the most common symptoms caused by a more widespread immune reaction are: headache, fatigue, rashes, puffiness, malaise, joint and muscle aches, swelling of feet and hands, and dark circles under the eyes (“allergic shiners”).

Onset of Food Sensitivities

There are some really interesting theories as to why food sensitivity is becoming more prevalent today than in older generations. The first is simply that previously, food sensitivities went undiagnosed, and people were simply labelled as “frail” or “sickly”. The next is the hygiene hypothesis listed above. Another theory is that our current food is no longer the food of our ancestors. Because of cross-breeding and genetic modification, many of the foods that we eat today actually bear little resemblance to our natural food sources. The development of food sensitivity is not so surprising when you consider that corn may contain frog genes, and soy has had genes inserted to make it resistant to pesticides.

Most Common Food Sensitivities

It is possible to be sensitive to anything that you put in your mouth, but there are common trends seen in practice. The most common food sensitivities are:

  • Dairy (symptoms may also be caused by an intolerance to lactose)
  • Wheat and gluten
  • Corn
  • Soy
  • Nightshade family of plants (tomato, potato, peppers, eggplant and tobacco)

Diagnosing A Food Sensitivity

There are a number of blood tests available on the market that you can have performed by your healthcare practitioner. These can test for IgG, IgE and IgA antibodies in the blood or IgA antibodies in the stool. They can be useful if you are completely unable to modify your diet at the moment. Unfortunately, because we do not yet fully understand how food sensitivities occur, these tests merely give us a direction to look, and do not provide us with complete answers. Some people with antibodies to a food will not show a reaction, while those with none will react strongly.

Note from Dr. Katy: In my clinical experience, I have found that the best way to discover your food sensitivities (if any) is to ask your body directly. It will be able to tell you exactly what foods cause which symptoms. Sadly, your body can’t talk, but if you set up the conditions with an elimination diet, it will clearly show you what’s going on.

Elimination Diet

In order to clearly identify which foods are triggering what symptoms, we must first give our immune system a chance to cool off and settle down. We do this by eating a hypoallergenic diet free from common allergens for 3-6 weeks (or more, depending on the severity of symptoms). If your symptoms do not improve at all after 6 weeks, it is unlikely that you are suffering from sensitivity to the foods you have removed. You may be reacting to foods on the safe list, or you may not have a food sensitivity at all. There are a number of resources online for doing your own elimination diet, or you can contact your naturopath for more information. After 3 weeks (or once your symptoms have resolved), you begin to reintroduce one food at a time in a controlled manner and journal your body’s response. Foods that cause reactions are listed with the type of problem created, so after a few more weeks, you will have a complete understanding of what foods cause you problems.

Managing Food Sensitivities

Unfortunately, with food sensitivities, there is no magic pill. The only way to ensure your symptoms stop is to completely avoid the offending food. This will give the immune system a chance to cool down and stop the symptoms. Ultimately, once you know what foods cause which symptoms, you can decide what you are willing to tolerate and what you are not. It seems overwhelming at first to completely modify your diet, but in my experience, most people feel so much better off of the offending foods that they laugh at the thought of ever eating them again.

New Research

There is evidence that after eliminating food sensitivities for at least a year (maybe several), some people can begin to reintroduce the food on a 4-day rotation without relapse. This means that they can once again eat the food, but cannot have it more than once every 4 days. Whether or not you can do this will be entirely trial and error. Ultimately, trust your body! Your symptoms will tell you what you can and cannot get away with. Ultimately, living without the symptoms of food sensitivity makes all of the hard work worthwhile.