It can seem strange at first to think that something you have been doing your entire life may be making you sick. This is especially true, when you had a few (if any) symptoms when you were younger.

This condition is relatively new to our understanding, and has only recently begun to be accepted by the medical community. We are constantly learning more about how it happens and what possible causes may be.

Symptoms of Food Sensitivity
Food sensitivity can cause a wide variety of symptoms in the body, which often makes it difficult to diagnose on first blush. Because of the complex mechanisms involved in the immune system, there are a variety of symptoms commonly associated with food sensitivity. When the immune response is just limited to the digestive tract, common symptoms include: gas, bloating, maldigestion, malabsorption, diarrhea, constipation, mucous, 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”).

Understanding the Terminology
When discussing issues with food, it is first important to distinguish between several different terms that are commonly used interchangeably in casual conversation. Food allergy, food sensitivity, and food intolerance are each caused by distinct processes in the body, despite their common use to describe food sensitivity. 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 (the severe type of allergic reaction that requires emergency treatment due to restricted breathing and a drop in blood pressure). Food intolerance, on the other hand, is the inability to properly digest a food, because of a lack of the required enzymes in the digestive tract. The most common example of food intolerance is Lactose Intolerance, in which individuals lack the lactase enzyme required to properly digest the sugar found in dairy products called lactose. 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.

Food Sensitivity
Because “food sensitivity” is still a bit of an umbrella term, it is difficult to completely define its boundaries. The most common immune response associated with food sensitivity is an IgG (G-type antibody) reaction, although some more current research is also associating it with IgA antibodies as well. While the exact mechanism of action has not yet become clear, there is a growing body of evidence that, in sensitized individuals, exposure to certain food proteins results in erratic immune responses, some of which can even trigger Autoimmune Disease. One severe example of this is the gluten sensitivity associated with Celiac Disease.

What causes food sensitivity?
The origin of food sensitivities is not yet known. Theories abound, and two of main contributing factors are thought to be a loss of gut integrity, and interestingly enough, a lack of parasites in our society. For more information on what causes a loss of gut integrity, and how it can contribute to food sensitivity, please see our Leaky Gut article. In the case of the “hygiene hypothesis”, it is believed that regular exposure to pathogenic bacteria, viruses and parasites all help to properly regulate our immune system. The development of sterile home conditions, antimicrobial products, and strict cleanliness has phased out this exposure in children. It is believed that in the case of food sensitivity, the parasite-targeting part of our immune system becomes “bored” without stimulation, and begins to overreact to normal gut contents. 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.

Why haven’t I been sick all of my life?
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)

How do I know what I’m sensitive to?
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 in this 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 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.

What can I do about it?
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 their offending foods that they laugh at the thought of ever eating them again.

Years Later
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!