Thursday, March 22, 2012

Food Sensitivities and Allergies

We take eating for granted. We know that we must eat in order to stay alive, but most of us don’t really think too much about what we eat as long as it tastes good. But what if what tastes good makes you sick? Not food poisoning sick, but rather vague symptoms that don’t seem to be related to the food you ate at all? Could you still be getting sick from your food? The answer is a resounding YES!

Many foods that taste great and that are even recognized to be “healthy foods” may make you sick if that particular food doesn’t happen to agree with your body (specifically your immune system). While most of us know about serious food allergies that can send people to the emergency room with swollen lips, hives, or difficulty breathing, many people are not aware of food “allergies” that may show up in a less dramatic manner. These more subtle food “allergies” or “sensitivities” may be the cause of significant symptoms or even chronic illness (e.g. gluten sensitivity leading to Celiac Disease). Minor food sensitivities are often missed as a cause of illness because the symptoms rarely show themselves immediately, which often makes it difficult to realize that a food sensitivity may be the problem.

So why do some people become sensitive to certain foods, what are the most likely culprits, and what can you do to find out if you are suffering from this problem?

THE IMMUNE SYSTEM DEFENCES

We all have an immune system that tries to protect us from injury and foreign invaders like bacteria and viruses. Sometimes the immune system gets overprotective and targets things it shouldn’t. This is what happens with food allergies/ sensitivities.

There are three major different types of immune responses your body mounts to different foods. These reactions are the result of three different types of antibodies, called immunoglobulins. We will discuss more of the specifics of each type lower in this post, but let’s take a brief look at them here to offer a basic understanding before we proceed further.

  • Immunoglobulin-E (IgE) -- This antibody is responsible for triggering very fast and very severe inflammation known as “anaphylaxis”. Left unchecked, this reaction can close off airways and become fatal. Severe allergies to peanuts or shellfish fall into this category.

  • Immunoglobulin-A (IgA) -- This antibody primarily works in the gut and is responsible for preventing harmful pathogens (bacteria, viruses, parasites, etc.) from taking up residence there. Unfortunately, IgA can sometimes mistakenly target foods (which are not harmful) as pathogens, causing an immune response of inflammation in your gut. The inflammation caused by IgA can cause damage to cells in your intestines, and this can manifest as disorders such as Celiac disease or Irritable Bowel Syndrome.

  • Immunoglobulin-G (IgG) -- This antibody is found throughout your body and is one of the main antibodies in your immune system. Symptoms caused by IgG activation can occur just about anywhere in your body and are usually related to inflammation. Though less severe, the effects can be far reaching and are implicated in a number of chronic illnesses.

COMMON SOURCES OF FOOD SENSITIVITIES

While there are many different types of foods to which people are sensitive, there are several that are the most common.

Gluten/Gliaden -- These two proteins, found primarily in grains, are particularly problematic for people who suffer from a sensitivity to Gluten or Gliaden. This particular sensitivity is also the cause of Celiac Disease (where it causes an IgA reaction, damaging the cells of the intestines). But they can also cause less intense IgG reactions which can cause lasting chronic health issues. In addition, IgE reactions can take place with gliadin, which could trigger asthma attacks or even full blown anaphylactic reactions.

Gluten and gliaden are found in many grains but are most prevalent in wheat, rye, triticale, barley, spelt, and oats.

Nightshades/Solanines -- Solanine (or Alpha-Solanine) is actually a poison that certain plants (in the nightshade family) produce to protect themselves from being eaten. Nightshade plants include the potato (not sweet potatoes or yams), eggplant, peppers (all types but not peppercorns), paprika, goji berries, and tobacco.

Solanine is the reason why it is incredibly dangerous to eat most parts of a potato plant. Solanines are particularly problematic, even without specific allergies (IgA or IgG), as solanine itself is toxic. Symptoms of solanine ingestion can include nausea, diarrhea, vomiting, stomach cramps, burning of the throat, cardiac dysrhythmia, headache, and dizziness. There is also an association between eating foods that contain solanine and certain chronic disorders including arthritis.

For more information on foods which contain solanine, visit the Arthritis Nightshade Research Foundation website.

Dairy products can contain several
different types of potential allergens.
Lactose/Casein/Whey (Dairy) -- These three parts of dairy based foods are a trifecta of food sensitivities. Casein and whey are proteins found in cow’s milk and lactose is the sugar found in dairy products. Food sensitivities can arise from allergic reactions occurring from any of these three components.

Casein is the name of a group of proteins that make up about 80% of cow milk. Casein is very chemically similar to gluten, and so a casein-free and gluten-free diet are often combined in people sensitive to either.

Whey is often used as a protein supplement in foods or products marketed at body builders or other athletes. It is used in many other food products and can cause problems for people who are sensitive to lactose, as whey is made up mostly of lactose.

Lactose is used in a wide variety of products. It is often used as a coating or filler for pharmaceutical medications and candies. It can also be used as a substitute for common ingredients in “low fat” foods. In addition, lactose is (bizarrely) used as an ingredient in processed meats like sausages or hot dogs. Ingredients such as “non-fat milk solids” are essentially just powdered lactose, and can cause reactions to people sensitive to lactose. (Lactose intolerance is not a food allergy or sensitivity but rather an entirely different problem that occurs in people who lack the gut bacteria needed to digest the sugar lactose).

Coffee is a common source of
methylxanthines (caffiene).
Methylxanthines (cocoa, tea, coffee, soda, caffeine, theobromine, theophylline) -- Methylxanthines are chemicals that behave like stimulants. They are found in coffee, tea, chocolate, and many commercially sold “energy” drinks. While they are added to some foods and drinks to provide a boost to energy, methylxanthines can cause allergies in people who are sensitive to them. Methylxanthines can trigger serious reactions including asthma attacks and serious inflammation. Methylxanthines can also be responsible for other allergic and sensitivity reactions that can cause problematic symptoms and chronic problems.

Zein (corn) -- Zein is a protein found in corn and is similar in nature to gluten in wheat. Though it is chemically different and much less likely to cause allergies, some people can still have adverse reactions. Since corn and corn related products are increasingly being used in food products (especially processed foods), you can easily be exposed to zein proteins without even realizing it. Avoiding processed foods can prevent much of this type of unexpected exposure.

Zein is a protein found
in corn.
Furthermore, zein-based products may become even more commonly used in processed foods if ethanol production from corn ever becomes a reality on a large scale. Since zein is a byproduct of making ethanol food companies will look for novel ways to include this new cheap source of zein in their processed foods.

Ovalbumin (eggs) -- Ovalbumin is the main protein that makes up egg whites (about 60-65%). Ovalbumin is used not only for cooking (as egg whites), but also in very different products you might not expect, such as vaccines.

IMMUNOGLOBULINS: THE IMMUNE SYSTEM SEARCH TEAM

Immunoglobulins are a class of proteins in your immune system commonly referred to as “antibodies”. These protein antibodies are designed to identify and neutralize dangerous foreign invaders such as bacteria and viruses. Immunoglobulins typically start off the immune system’s response and play a crucial role in triggering inflammation. As we discussed in our inflammation article, this is a very important step in responding to health threats, but can cause problems if left unchecked.

The ends of the immunoglobulin proteins have specific receptors for different types of molecules. In this case, some types of foods contain specific molecules (e.g. proteins, chemicals, etc.) which may activate certain types of immunoglobulin. Because different people have unique immune systems, some people may be sensitive to foods while other people are not. Essentially, the three different types of immunoglobulin reactions are all  considered to be an “allergy” but since the effects of IgA and IgG are not as obvious as IgE reactions they are differentiated by using the term food “sensitivities” instead.

To review and expand on our earlier discussion, each type of these immunoglobulin proteins is named with an "Ig" prefix which stands for immunoglobulin. The three major types of immunoglobulin related to food sensitivities are IgE, IgA, and IgG.

IgE -- This is the immunoglobulin responsible for the severe allergic reaction of anaphylaxis. In people with, for instance, severe peanut or shellfish allergies, exposure to even a very small amount of the allergen causes a very fast and extremely dangerous inflammatory reaction. This can cause symptoms ranging from hives up to severe throat swelling that can cause a person’s airway to close off. People who have a severe allergy like this often carry around an “epi-pen” (a syringe containing epinephrine) for emergencies. If you or anyone you know ever faces this type of an anaphylactic reaction it is essential to immediately seek medical attention at the nearest emergency department. While an epi-pen can save your life, it is very short acting and meant to only last long enough to get to emergency medical care.

IgA -- A reaction involving IgA is called “immediate hypersensitivity”, because the reaction is pretty quick. IgA is primarily found in the gut, where it works to prevent harmful pathogens from causing illness. IgA is present in the lining of the gut and works to repel foreign invaders by causing an immediate inflammatory response to engulf and dispose of the problem. In this way, pathogens like bacteria, viruses and parasites are attacked before they can get into your bloodstream and spread.

IgA reactions includes disorders like Celiac Disease, where gluten reacts with IgA and causes inflammation in the cells of the gut. This inflammation causes physical damage to the cells that line the intestines leading to pain, chronic inflammation and long term damage to the part of the gut wall that absorbs nutrients (the villi).

A wide variety of foods can provoke an IgA response. Since most of the cells that produce IgA are in the gut, most of the symptoms of an IgA reaction happen there as well. These symptoms can range anywhere from pain in the intestines to serious internal bleeding, depending on the type of exposure and how sensitive you are to the specific allergen. Furthermore, IgA reactions can lead to gut wall damage leading to poor nutrient absorption and even a “leaky” gut. We discussed problems related to a leaky gut syndrome in our post on dysbiosis.

IgG -- IgG reactions can manifest just about anywhere in the body, but unlike IgE and IgA reactions these do not manifest immediately; they develop over the course of several days. This poses a real problem in identifying potential foods that may be causing an IgG reaction. This is a big reason that this particular type of food sensitivity can be so difficult to uncover. Newer testing methods (discussed below) allow physicians to better identify this type of food sensitivity.

IgG is the most widely utilized immunoglobulin in the body, making up about 75% of all antibodies in the blood. While IgG is involved with many different types of immune responses, we will focus primarily on the food related ones in this article. In this case, proteins or other chemicals from food get absorbed into the blood, where IgG interacts with them, triggering inflammation. Symptoms from this type of reaction can include joint pain, headaches (including migraines), chronic pain, and irritable bowel syndrome.

TESTING

Fortunately, there are easy ways to find out the foods to which you might be sensitive. There is a test called an “Enzyme-linked immunosorbent assay” (or ELISA), which can determine which, if any, of these antibodies are present in your body. This allows a personalized look at what food sensitivities you may have and how severe they are.

A few companies (like US BioTek) offer an ELISA test which looks at many of the most common food allergens and how they trigger IgA and IgG in your body. Using the information gathered from this test, you can avoid foods that could be negatively impacting your health by causing chronic inflammation or other health problems. This sort of testing can quickly and easily show you the food types which will trigger immunoglobulin responses, and even which variety (IgA or IgG) each type of food reacts with in your body.

Prior to the development of ELISA testing, the standard method of testing for food sensitivities was an elimination diet. An elimination diet typically removes one or more of the common types of food allergens (e.g. gluten, casein, etc.) from a patient’s diet. It is important to completely remove the type of food for between 4-6 weeks to eliminate any possibility of lingering IgG reactions. If the patient’s symptoms improve, then it is likely that removing an allergen may have helped. At this point, the patient can start adding foods back slowly, one at a time over the course of several weeks. If symptoms return after adding a suspected food, it is very likely that the patient has some sort of allergy to that particular food and it should be avoided in future.

Elimination diets are still used and are easy for anyone to do who thinks they might be sensitive to certain foods. Since eliminating problematic foods is the treatment for food sensitivities as well, training people to remove foods during the testing phase also helps prepare and teach them to maintain avoidance after a food sensitivity is discovered.

CONCLUSION

It’s important to remember that virtually any type of food can cause an allergic reaction, even if you don’t notice it right away. Any of a number of compounds in foods could cause any of the three types of immunoglobulin to trigger a response, either immediate or delayed. Every person will react differently as everyone’s immune systems is slightly different.

It’s important to know the types of foods to which you might be sensitive so that you can take steps to avoid them. You might not have an obvious severe anaphylactic response, but eating foods that cause an IgA or an IgG reaction can lead to chronic health problems.

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Researched and written by Dr. Rebecca Malamed, M.D. with assistance from Mr. Malcolm Potter.

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