The Surprising Facts About Food Sensitivities

Food is one of life’s wonderful pleasures, but for some it can be a source of pain and frustration. I receive questions about food sensitivities almost daily because there is so much misunderstanding and conflicting information out there. It’s understandable why people are confused.

Food allergies are real—there is no debate about that. But when it comes to the best approach for dealing with them, there’s a gray area the size of Canada.

Dr. Kari Nadeau of Stanford School of Medicine reports that nearly 15 million Americans have food allergies ranging from moderate to severe, including one of every 13 children. (1,2) The incidence of allergies and sensitivities may be even higher when you consider how many unexplained symptoms are experienced every day. Between 45 and 60 percent of the general population suffers from health conditions whose cause is not identified. It seems reasonable that a fair number of these symptoms could be explained by food reactions, particularly today’s chemical-laden processed foods.

People react to foods for numerous reasons. Food allergies tend to run in families, suggesting a genetic component. However, genetics can’t explain all food sensitivities, so we must look at environmental and lifestyle causes.

Identifying which foods may be causing certain symptoms is a bit like trying to find a needle in a haystack, but it’s not impossible. The good news is, once you successfully identify an unfriendly food, you don’t necessarily need to deprive yourself of that food forever—many individuals who have experienced food sensitivities have reversed them.

Before getting into the details about diagnosing food sensitivities, it’s important you have a basic understanding of the difference between food allergies and other food reactions, because you would approach them quite differently.

Food Allergies vs. Food Sensitivities

Food allergies (aka food intolerances) are classified as hypersensitivity reactions—meaning, reproducible adverse reactions triggered by foods that are well tolerated by most people. The reaction is often to one chemical component in a food.

Food hypersensitivities can be divided into two main groups: those caused by a reaction by your immune system (immune-mediated hypersensitivities) and those that are not (non-immune mediated hypersensitivities). (3)

Immune-Mediated Hypersensitivities

An allergic reaction in which the body produces IgE (Immunoglobulin E) antibodies against the offending food; some are severe and even life threatening

The child whose throat immediately swells up immediately after eating peanuts exemplifies the “classic food allergy” of the immune-mediated type. The release of histamines causes severe swelling, breathing difficulty, rash, itching skin and sometimes anaphylactic shock. Most people know the triggering food because these reactions are immediate.

Milk, eggs, peanuts, tree nuts, fish, soy, wheat, and crustacean shellfish account for 90 percent of significant reactions. These must be taken very seriously, and managed with one’s doctor. Anaphylactic reactions are medical emergencies and should be avoided using all means necessary.

However, these classic food allergies are only one type of immune-mediated hypersensitivity. Some immune-mediated hypersensitivity reactions take longer to develop. Examples include celiac disease, reactions to cow’s milk and soy. Over time, these can lead to chronic inflammation, asthma, eczema, enterocolitis and other serious health problems.

Non-Immune-Mediated Hypersensitivities: Food Sensitivities or Intolerances

An adverse food reaction not involving the immune system

Most people know if they have a true allergy to a food, as per above.  However, there is this category of food reactions (known as sensitivities) that may not manifest the same way, but can still cause symptoms, perhaps delayed, presenting hours to days after consumption. Severity depends on quantity of the offending food consumed as well as overall health status. Some people will be sensitive to a food throughout their lifetime, but others can “cure” their sensitivity by reducing exposure.

Some foods contain chemicals the body perceives as foreign (tyramine, histamines, sulfites, nitrates and nitrites, etc.), prompting sensitivities. Processed foods contain thousands of foreign chemicals notorious for triggering adverse reactions.

One of the best-known examples of non-immune mediated hypersensitivity is lactose intolerance, which affects 75 percent of the adult population but does not always produce symptoms. In addition to lactose, other common intolerances include gluten, preservatives and additives, and tyramine (common in cured meats, aged cheeses and smoked fish).

Food sensitivities are varied but may produce headache (including migraines), insomnia, gastrointestinal distress (including diarrhea and IBS), skin rashes (eczema, psoriasis), low energy, and impaired cognition. The delay in symptoms makes it challenging to identify the culprit. Over time, repeated exposure can lead to autoimmune conditions.

Why Are Allergies on the Rise?

Research shows nearly half of all Americans age six and older have an allergy to something—45 percent test positive to at least one allergen. (4) Since 1997, the reported number of reported allergies among children has increased by 18 percent, including food allergies. Why are food allergies on the rise?

While there may be many factors at play, I believe the short answer to this question is that we’re not eating like we used to. We evolved as hunter-gatherers whose diet was marked by high food quality, variety and moderation. Paleolithic humans (living between 10,000 and 8,000 B.C.) are believed to have consumed between about 100 and 200 different plant foods each year—and they had no processed foods or chemicals to test their immune systems. Paleo humans would never have consumed the equivalent of a bag of cashews in one day. Our sheer variety of foods distinguishes us from other species.

Most people today consume the same several foods every day, and even the most diligent eaters are exposed to a variety of chemicals along the way, which increases the risk for allergies and sensitivities. These reactions are our body’s way of trying to protect us.

Studies show dietary diversity is beneficial to human health. One study showed women consuming more than 16 to 17 items from a list of healthy foods reduced their risk of dying from all causes by 42 percent when compared to women who consumed fewer than nine items from the list. (5) But there’s a caveat: too much of a good thing can be too much of a good thing. Another study illustrated how increased dietary diversity may lead to overconsumption and raise your risk for obesity and diabetes. (6)

Evidence exists that the more of a food you consume, the higher your risk for developing a sensitivity to it. Our nomadic ancestors ate seasonally, which prevented them from overdoing it on any one food. Different ancestries and blood types have been associated with different hypersensitivity tendencies. Concepts of eating right for your blood type have very much been based on this premise.

One note about food cravings: we tend to crave the foods to which we’re hypersensitive. This seems counterintuitive, and the reason isn’t clear. One theory is that we become “addicted” to chemical messengers, such as histamine and cortisol, that our bodies produce in response to allergens. We may experience a soothing response from these chemicals, prompting us to eat more. (7)

How to Identify Your Own “Unfriendly Foods”

Resolving sensitivities requires taking a break from eating the triggering foods, so the first step is to determine which foods you need to avoid. You may be hip deep in conflicting information, so let me share with you what I know. The most common methods of diagnosing food sensitivities are the following: (8)

• IgG/IgG4 testing (ELISA)
• Cytotoxicity testing (ALCAT)
• Electrodermal testing or vega testing
• Nambrudipad’s Allergy Elimination Technique (NAET)
• Applied kinesiology or muscle testing
• Pulse testing
• Hair analysis
• Elimination diets and food challenges

Most of these are unreliable, expensive, or not terribly accessible. Electrodermal testing has a reputation for inaccuracy. (9) Muscle testing depends on the skills of the practitioner and, at least in my experience, is not always consistent. Going into each of these approaches in detail is beyond the scope of this article, but the bottom line is, there is no good scientific evidence that any are reliable—save for one.

The most reliable way to determine your food sensitivities is with an elimination diet and food challenges.

Unfortunately, this is also the most time and labor intensive of all the options, but it’s the only method that yields consistent results—and the price is right because it’s free.

I’m the first to admit that spending a month or so tracking and testing my foods may not seem as attractive as a single blood test or skin probe, but the scientific evidence just isn’t there.

IgG/IgG4 Testing Called Into Question

I have used IgG blood tests myself and was recently shocked to learn that IgG levels may not actually reflect food intolerances.

IgG serum testing involves measuring the amount of IgG4 (Immunoglobulin G4) your body produces in response to various foods. Proponents claim that the higher your IgG4 level is, the more intolerant/hypersensitive you are to that food. However, it isn’t that simple. IgG4 may have both protective as well as harmful properties.

The latest discussion revolves around IgG levels reflecting immunological tolerance—repeated exposure to foods rather than hypersensitivity. There is poor correlation between IgG values and symptoms, and high IgG antibodies do not mean you have a hidden reaction to that food. (10, 11, 12) Many studies support this view.

For example, people recovering from dairy allergy show increasing levels of IgG4. (13) If IgG4 levels really reflected sensitivity, then their levels should be decreasing. Also, children with eczema and egg or milk allergies with higher levels of IgG are found to have greater tolerance to these foods later in life. (14) Our bodies produce IgG in response to all of the foods we eat, and it seems that this biological response is much more complex than given credit for.

For more information, I highly recommend an article by Anna Laforest. Her entire website is an excellent resource for information about food sensitivities, well written and well referenced. (15)

Indeed, some people have experienced improvements in their health by avoiding foods per IgG results. I, myself experienced this and of course I took this to mean the tests were accurate. However, I might have avoided some problematic foods by chance, and I would have certainly nailed down those sensitivities with an elimination diet. Expectations always play a role, and the placebo effect is alive and well.

There is no denying the science. Allergy and immunology associations around the world have issued position statements warning against IgG blood tests. (16, 17)  Dr. Rob Loblay, clinical immunologist at Royal Prince Alfred Hospital in Australia, had this to say:

We have not found any correlation between challenge results and IgG blood tests, so we don’t think they’re helpful. IgG antibodies to food are simply a marker of exposure, and IgG4 subclass levels correlate with the development of clinical tolerance in people who have outgrown their IgE mediated food allergies. This has nothing to do with intolerances, in my opinion. (18)

How to Deal with Food Sensitivities: Eliminate, Challenge, Modify

Investigating your food sensitivities is deceptively simple. Basically, you eliminate all potentially triggering foods and food chemicals with an elimination diet, and then add them back one at a time until the culprits are identified (food challenges). The final phase is implementing a modified diet consisting only of your “friendly foods.” In a 2006 study involving IBS sufferers, this general approach was found beneficial for 100 percent of study participants. (19)

Step 1: Elimination Diet

An elimination diet involves eating only the foods least unlikely to cause problems in the majority of individuals. Versions of the diet differ in terms of the exact food list, but they all attempt to remove the most common allergens such as gluten, dairy, eggs, soy, peanuts, corn, alcohol, processed foods and refined sugar. An elimination diet should be done for at least four to six weeks—and many recommend three months, which gives your gut ample time to heal.

Many food allergies result from “leaky gut syndrome,” a condition in which your intestinal wall is damaged and unable to keep large molecules out of your bloodstream that trigger hypersensitivity reactions and inflammation. Some experience detox symptoms (aka Herxheimer reaction) in the first or second week, but most people with food sensitivities feel significantly better after just two or three weeks on an elimination diet.

If after several weeks you have no change in symptoms, then it’s unlikely food sensitivities are your problem. However, if you do experience a lessening of symptoms, then you can proceed with the next phase, which involves systematically reintroducing foods. You must be feeling good to proceed to the next step—otherwise, you won’t be able to tell when a food produces symptoms.

Step 2: Food Challenges

Individual foods are reintroduced into your diet one at a time, and each of these is considered a “challenge.” If you have a reaction to a challenge, then discontinue that food and wait until your symptoms subside, plus a few days, before moving on to the next food. Foods will either enhance your energy or drain it; if your energy takes a dive, that’s highly suspicious for sensitivity.

Gluten and dairy products are often the first challenges because they are so problematic. Reactions to food chemicals are also common such as salicylates, benzoate, amines, MSG, artificial colors and the like.

If you are sensitive to a food, it’s often a reaction to one chemical, so it’s wise to test other foods that are known to contain the same chemical (cross-sensitivities). When challenge foods contain more than one chemical trigger, the ordering of the challenges is important to systematically rule out all possibilities. This all takes a bit of patience and strategic sleuthing.

You may want to test different types of a food. Do you react to wheat? See how you do with spelt or kamut. Today’s industrialized wheat is typically higher in gluten and doused in agricultural chemicals, which may account for many of the increased problems. Different types of wheat have different numbers of chromosomes, and some studies show that older wheats, with fewer chromosomes, tend to have lower levels of gliadins, the type of gluten proteins that seem to cause most sensitivities. (20, 21)

Do you react to dairy? Cow’s milk contains more than 20 different proteins, any of which may produce hypersensitivity reactions. Test out your responses to goat’s milk. Some people do better with non-homogenized milk and/or non-pasteurized milk — if they can have access to these options. Pasteurization does change milk proteins, making them unfamiliar to the body, which is a setup for sensitivity reactions.

Your “threshold dose” of a problem food can decrease after avoiding that food for a period, so be sure to test those foods in very small quantities—especially if you had a true allergy. Sensitive people can experience dangerous reactions when reintroducing foods, even in amounts that previously did not cause symptoms, so proceed with safety in mind.

Step 3: Modified Diet

Once you’ve tested everything and have a grasp of what causes what, you have your modified diet. To avoid future problems, avoid adding more than one new food at a time so that if you do experience a reaction, you’ll know what caused it. After all of this self-testing, you should be a pro at listening to your body.

You can always reintroduce unfriendly foods down the road to see if you have finally resolved a sensitivity, but proceed with caution. Most recommendations are to wait four to six days after reintroducing a food before calling the coast clear, as some reactions take this long to manifest. Other experts recommend waiting a full seven days.

As your gut continues to heal, you may no longer be sensitive—or less so. How long does it take the gut to heal? It varies, but three months is the minimum. If after three months you reintroduce a food and experience a return of symptoms, you may need to avoid that food for six months or longer. It’s possible you might be able to eat it eventually, but infrequently and in smaller amounts.

Final Strategies to Ensure Your Success

Food sensitivities are real. Even a “healthy food” can cause an adverse reaction in your body, producing symptoms you cannot explain and would never consider food-related. You can’t rely on medical technology to give you a clear path forward because, when it comes to food sensitivities, reliability on laboratory testing not been a success. The good news is that a basic elimination diet can tell you everything you need to know to feel better. Here are a few tips:

• First and foremost, listen to your body.
• Stick to high quality, nutrient-dense whole foods. A 2014 review comparing the merits of many popular diets concluded the best diet is simply whole foods that are close to nature. (22)
• Become a locavore, and eat seasonally whenever possible.
• Rotate your foods. On a rotation diet, a food is eaten only once every four to six days, allowing the body to clear it between exposures. This helps you avoid excess exposure and gives you a better idea what foods might be causing a problem. Reduce your consumption of more problematic foods to no more than once every seven to 10 days.
• Supplements that may be beneficial include omega-3 fatty acids to reduce inflammation, probiotics to replenish gut flora, betaine hydrochloric acid (HCl), L-glutamine to aid in the repair of gut lining, digestive enzymes, deglycyrrhizinated Licorice (DGL), slippery elm, marshmallow root, and caprylic acid. (23)