Clarifying Food-Related Issues

When you eat certain foods, have you found yourself experiencing nausea, stomach pain, or mind fog? Or, do you notice itching, rash, or hives? The symptoms of food intolerance and true food allergy can crossover, but these two conditions fall under two quite different categories. Before you classify yourself as having an allergy, you should look back on your food history to identify what is truly going on, and how to manage it. 

Food Intolerance

Common symptoms of food intolerance include nausea, abdominal pain, bloating, vomiting, reflux, diarrhea, headache, and even irritability. Overall, food intolerance stems from an inability to process these foods in the digestive system, which range from having deficiencies in enzymes to having intolerance to food additives such as dyes and flavor enhancers. 

Lactose intolerance, and the lesser known, fructan intolerance are examples of the human body having a deficiency in the enzymes needed for digestion. Diets high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) consist of short-chain carbohydrates that are poorly absorbed in the small intestine and passed on to the colon. As a person with lactose intolerance, for example, having soft cheeses or dairy will likely cause you bloating and gas because of the lack of lactase enzyme to digest the lactose sugar early in your digestive tract. This is the same idea for fructan intolerance, which has been on the rise due to the increasing consumption of wheat based foods in the Western diet. When eating foods high in fructans such as pasta, onions, and barley, only 5-15% of the molecules are absorbed in the small intestine, while the rest passes to the large intestine where they ferment with our natural bacteria flora. Not only does the bacteria break down these carbohydrates and release gas, but the carbohydrates also pull in and retain water, which explains why you feel bloating, gas, and diarrhea. 

Not all food intolerances are enzyme-deficient related. Gluten intolerance, contrary to Celiac disease or wheat allergy, will cause the symptoms of abdominal pain, nausea, fatigue and/or mind fog, however, these symptoms rarely warrant for emergency care. Another compound, monosodium glutamate (MSG), has also been mislabeled as a food allergen. However, symptoms related to MSG consumption do not involve the immune system. Like some of the other types of intolerances, some individuals experience bloating, abdominal pain, headache, flushing, and sometimes numbness and tingling. Despite this, researchers acknowledge that these symptoms have been presented as mild and short-lived, and also do not warrant emergency care. Many of the foods and compounds become grouped under “food intolerance” without an established reason, and researchers are still studying to understand why our bodies act symptomatic with certain food consumption.

So how do I identify and avoid the foods that I can’t tolerate? All in all, detailed history taking and conducting dietary investigation will prove to be useful. Breath tests are a possibility for sugar related intolerances - at the doctor’s office, you drink a beverage of fructose, lactose, or another sugar, and then the hydrogen byproduct produced is released in the breath. The hydrogen is from the fermentation of the flora digesting the excessive sugars. The hydrogen in your breath is then measured in timely intervals. Using this data, the doctor would then be able to suggest whether your symptoms correspond to a sugar related intolerance. Despite the availability of this testing, breath tests are known to have lower reliability and can be imperfect in diagnosing you with an intolerance. Instead, trying elimination diets and keeping a food journal can successfully help identify food groups that you are symptomatic to. By removing or reducing FODMAP foods, for example, you should be able to eventually notice changes in your gastrointestinal symptoms, if this is something you’re intolerable to. 

Food Allergy

Common symptoms of food allergy involve a rash, hives, nausea, cramping, diarrhea, itchy skin, shortness of breath, chest pain, and in more severe cases, anaphylaxis. Anaphylaxis typically involves severe rash, nausea, vomiting, and difficulty breathing, and can lead to unconsciousness or even death. 

Contrary to food intolerance, food allergy is due to an immune system response when our body mistakes the proteins in the specific food as harmful. The immune system overreacts via production of immunoglobulin E (IgE) antibodies, which stimulates histamine release by immune cells- this can irritate the nerves (causing itching) or cause leaking of the capillaries (causing redness or swelling). Another difference with intolerance is that food allergy only requires a small amount of the food protein to stimulate a reaction, whereas intolerance symptoms can vary depending on the amount eaten. 

There are 8 major food allergens that make up most of the serious food allergy reactions, including milk, egg, peanut, tree nuts, wheat, soy, fish, and shellfish. Food allergies are most common among children, but some allergies can be developed later in life, such as to shellfish. On the other hand, people can also outgrow their childhood allergies especially if it is milk, egg, and soy allergy. Interestingly, people allergic to pollen may sometimes have oral allergy syndrome to certain fresh fruits, vegetables, or nuts due to the cross-reactivity between the proteins. Understanding food allergies is pretty complex and we learn more about it every day!

Food intolerances can often be mistaken or mislabeled for an allergy. Remember, food allergy involves hypersensitivity that is IgE mediated, and will involve immediate reactions within 10-15 minutes (and at most an hour) to even small amounts of the food. This should also be a reproducible symptom to the food, so you should be able to identify what food group is causing the clinical reaction pretty immediately. For diagnosis, an allergist will extensively review your food and symptom history, supplemented with skin testing as well as blood testing (which measures specific IgE level to certain food allergen). 

While diagnostic testing exists, skin testing has high sensitivity, meaning they can catch actual cases, but low specificity, meaning there is bound to be many false positives. In fact, almost half of positive skin prick testing are actually false positive. Researchers theorize this may be due to the complex breakdown of proteins in our digestive system or due to cross-reactivity between different proteins, but there is no exact reason to explain this sensitivity. This is also the similar for IgE blood testing; without extensive history intake, the doctor cannot diagnose you with just simple blood testing due to the prevalence of false positives. On the other hand, because skin testing is highly sensitive, there is a low probability of false negative- meaning that if your skin test is unremarkable for a food allergen, it is highly unlikely you are allergic. Just as with food intolerances, implementing elimination diets and using food journals will be most helpful for you and your doctor by narrowing down suspected foods to do allergy testing against.

If the blood work and skin prick testing show to be unremarkable and clinical history does not indicate food allergies, the doctor may suggest a supervised oral challenge completed either at home or in the office. Typically, you are fed a small amount of the food and then observed for some time to ensure you do not have clinical reactions. Then the dose of the food continues to increase until you have reached the target amount without issues. This is reliant on the patient being able to vocalize any symptoms they are feeling. 

If the blood work, skin prick testing, and the clinical history do suggest food allergies, then the allergist would recommend avoiding these foods completely. Sometimes certain foods are hard to avoid, as some cross-contamination can occur. In instances where you are experiencing minor symptoms, your doctor may suggest having Benadryl on hand to take as needed. During more serious episodes, you would likely be advised to carry an Epinephrine Auto-Injector for rescue. Please refer to our blog “Future Outlook on Food Allergy Treatment” to learn more about options regarding food allergies.

Sensitivity

You may have heard this word before, but it is a term that we have to be careful using. Food “sensitivity” is a terminology that is often inaccurately used by our patients, who may use this in place of a true allergy or intolerance. In the media, alternative medicine practitioners and blood testing industries may claim that they can test your food sensitivities, often utilising a food IgG test. However, be wary of this! Contrary to IgE, the presence of high IgG indicates a normal response of the immune system responding to food antigen, and stems from memory, not hypersensitivity/allergy. Often IgG tests can be elevated for foods you truly are not allergic or intolerable to, which needlessly removes what would otherwise be a safe and nutritional food from your diet.

Celiac Disease

Another food related problem some may have heard of is Celiac Disease. In short summary, Celiac Disease is also immune related, but is different from food or wheat allergy in that it is IgA mediated and involves severe abdominal pain and weight loss. Expect more information on Celiac Disease to be posted soon!

*********

Starting a food diary will help you in the preliminary investigation of your food-related symptoms. If you continue to have any concerns regarding food-related issues, please consult with your primary care physician, gastroenterologist, or allergist to properly discuss, diagnose, and treat your symptoms!