October 2011 Issue
Food Intolerances vs. Food Allergies
By Maura Keller
Vol. 13 No. 10 P. 52
Here’s how to distinguish between them and make an accurate diagnosis.
Turn on the television or open a newspaper, and you’re likely to find information on food intolerance and allergies. From peanut allergies to celiac disease to lactose intolerance, more and more attention is being paid to these food issues, causing healthcare providers and consumers to take notice and evaluate food consumption.
The differences between food allergies and food intolerances are often misunderstood because many people believe they’re the same; the truth is, they’re not.
“A food allergy is an immune system response when the body mistakes a particular food as a harmful substance,” says Melanie Silverman, MS, RD, IBCLC. “IgE antibodies are released, mounting a defense against the food in the body with a release of chemicals like histamine, causing the allergic reaction. Symptoms of an allergic reaction can manifest in a minor way as rashes, itching, hives, or swelling or in a severe way when people have serious trouble breathing and can lose consciousness. As a result, a food allergy can be fatal.”
As Silverman further explains, a food intolerance, often called a nonallergic food hypersensitivity, doesn’t involve the immune system and is more common than the diagnosis of a food allergy.
“Food intolerances often are delayed in their response and difficult to diagnose,” Silverman says. “The triggers are substances that naturally occur in foods, arise in food processing methods, or are added during processing. One of the most common food intolerances is lactose intolerance. There’s a deficiency in the digestive enzyme lactase so the lactose in milk isn’t digested well.”
According to Susan Linke, MBA, MS, RD, LD, CLT, who specializes in chronic inflammatory conditions related to food sensitivities, allergies, and intolerances, there’s a lack of consensus about the definition of food intolerances and food allergies. Therefore, there’s overlap and interchangeability in the literature.
“In general though, adverse food reactions can be classified as immune and nonimmune,” Linke says. “The immune category can be further subdivided into allergies and sensitivities. Food sensitivities are frequently confused with food allergies although they involve different immune mechanisms and have different characteristics. Frequently, I refer to food intolerances as the body’s ‘mechanical’ problem or failure—for example, the inability to break down and digest a food due to an enzyme deficiency.”
As Jan Patenaude, RD, director of medical nutrition at Signet Diagnostic Corporation, explains, generally food intolerances stem from multiple reasons, the main one being a lack of certain enzymes, whereas food allergies or sensitivities generally involve the immune system. “Yes, they’re often misunderstood, even by RDs, but especially amongst the general public,” Patenaude says.
Weeding Out the Culprits
While most food intolerances are found through trial and error, there are methodologies you can use to help patients identify and isolate these intolerances.
“Although testing is best, not all medical offices or labs are equipped to handle some of the testing required to diagnose some intolerances,” Linke says. “In the case of lactose intolerance, for example, it’s much easier (and cheaper) to avoid drinking lactose than to undergo breath testing. Small intestinal bacterial overgrowth (SIBO) also is diagnosed with breath testing, but many physicians that have experience working with SIBO and don’t have easy access to breath testing prefer to prescribe the necessary antibiotics to eradicate the bacterial overgrowth.”
Following identification of food intolerances, avoidance of the offending foods is the short-term recommendation, but in the long term, it’s important to investigate the underlying cause of the intolerance since, in many cases, food intolerances are reversible.
Patenaude prefers to see whether the intolerance has a cause and address it, rather than having a client avoid a good deal of perfectly healthful foods forever. “So, if it’s SIBO, parasites, or enzyme deficiencies causing the intolerances, address those first,” Patenaude says. “Consider adding digestive enzymes to see if they help, such as lactase, Beano, or diamine oxidase for histamine intolerance.”
Elimination diets also are an important part of the process. As Linke mentioned earlier, elimination of some foods, like milk, often is easier than undergoing expensive and uncomfortable testing.
“Often food intolerances are found through trial and error, but an elimination diet is the optimal way to help patients identify food intolerances,” Silverman says. “It’s also wise to rule out any food allergies with a trip to a board-certified allergist for testing before patients embark on an elimination diet to test for food intolerances. If food allergy testing is negative, start an elimination diet with the help of a registered dietitian experienced in food allergies and intolerances.”
According to Mimi Girten, RD, LDN, at Children’s Hospital of Philadelphia, a high degree of nutritional expertise, awareness, and careful food selection is essential to ensure the health and well-being of the client.
“The RD must be vigilant at assessing and reassessing a client’s diet logs, eliminated foods, and supplements. A client’s lack of nutritional guidance by an RD when eliminating food from their diet can result in severe deficiencies,” Girten says. “There are some food intolerances, such as lactose intolerance, where individuals may be able to reduce the amount of the food consumed and not totally eliminate it from the diet. If dairy is totally eliminated from the diet, additional calcium and vitamin D may need to be supplemented. Strict avoidance is the only way to prevent a food allergy reaction. Many people outgrow their food allergies, although peanut, tree nuts, fish, and shellfish are often considered lifelong allergies.”
While elimination diets certainly can be a part of the process in identifying food intolerances or sensitivities, E. A. Stewart, MBA, RD, says that for them to be effective, they must be restrictive at the beginning, which can be difficult for many patients.
“For instance, a typical elimination diet will allow foods such as rice and pears from the start; however, these foods, while not typically allergenic, may just as frequently cause symptoms in food-intolerant individuals as often as foods such as milk and wheat do,” Stewart says. “If a client is really motivated to do a strict elimination diet, we’ll start with just a very few items, assess tolerance, and over the course of a few days slowly add back individual foods one by one and assess for reactions. Again, this scenario will only be successful with an extremely motivated patient.”
Strategies for Elimination
To start the elimination diet process, Silverman recommends patients do the following:
• Start a food diary. Keep a detailed food record, including meal and snack times, for about two to three weeks. At this point, no food is off limits. If symptoms occur with a particular food, ask patients to record the reaction in detail.
• Become a super sleuth. After the two weeks, study the food record closely and identify trends in the records with foods eaten and symptoms experienced.
• Avoid the alleged offender. Ask patients to avoid the offending food for four to six weeks with the goal of being symptom free during this time. The last step of the elimination diet is the challenge. Ask a patient to introduce one of the suspect foods back into the diet and see whether there’s a reaction. If he or she experiences the reaction, you know there’s intolerance to that particular food and the recommendation is to avoid it.
“I like to refer to elimination diets as a windshield wiper wiping off a dirty windshield,” Linke says. “After the windshield is wiped off, I can clearly see the cracks that are left and deal with those individually.”
The next steps vary from patient to patient and depend on their tolerance to symptoms. “Once an offending food is identified, we need to educate the patient on which foods are safe [to eat],” Silverman says. “If there’s a large group eliminated (such as milk in lactose intolerance), we need to ensure that other sources of calcium are in the patient’s diet via food or supplementation. As in food allergies, the treatment is the same: Avoid the offending substance that sets off the reaction.”
Unfortunately, many patients try to identify food intolerances on their own, which can be a huge mistake. As Linke explains, this makes it very confusing because the characteristics of allergies, sensitivities, and intolerances can be similar in many cases. In addition, food sensitivities can take anywhere from 72 to 96 hours to produce a symptom, and by that time, the patient can confuse the cause of the symptom from a food eaten three days earlier with a food introduced that same day.
“If a patient is having difficulty identifying trigger foods, as is often the case, there are other ways of identifying offending foods,” Stewart says. “I use the LEAP [Lifestyle Eating And Performance] assessment protocol in my practice to determine if food sensitivity testing may be warranted. This helps take much of the guesswork out of the equation.”
Depending on the type and severity of symptoms identified, Stewart may recommend either a FODMAPs diet approach or a LEAP Mediator Release Test to determine which foods the patient is sensitive to.
“The big advantage to both of these approaches is that the initial diet is much less restrictive than with a strict elimination diet, which greatly improves both patient compliance and patient outcomes,” Stewart says.
Rebecca Dority, MS, RD, LD, CDE, instructor in the department of nutritional sciences at Texas Christian University, says patients may eliminate too many foods at once or reintroduce foods too quickly. “They also might not realize that dosage of the food may play an important role in the severity of symptoms,” Dority explains. “Also, since nutrition information is available to us via so many different mediums, there certainly have been cases where patients hear controversial information regarding side effects from foods and assume that those foods are causing their symptoms.”
Dority stresses the importance of teaching patients to read labels because certain food components may have different names and can be identified in multiple ways. “When an additive or preservative is causing the intolerance, patients often are surprised how many foods contain them,” Dority says. “Additionally, if an elimination diet is practiced (whether temporarily or not), the RD needs to assess what potential nutrients the patient might be eliminating in his or her diet. The RD can then come up with specific alternatives, whether food or supplement, to make up for what will be missing in the diet.”
Communication and coordination of care with a board-certified allergist and the other members of the allergy team also is essential. “The allergist and the RD should develop a strategy with the client for the reintroduction of foods,” Girten says. “It’s important to seek client input when discussing the reintroduction of foods. Specific guidelines defining the type and timing of the foods to be introduced and a course of action based on the result of the reintroduction also are needed. The RDs must provide clients, families, and caregivers with education on allergen avoidance, label reading, food preparation and storage, meal planning, cross contamination, dining out, travel, school/work modifications, and local and national resources.”
— Maura Keller is a Minneapolis-based writer and editor.
Common Food Intolerances
• Lactose: This is a sugar in cow’s milk that requires the enzyme lactase to be broken down into simple sugars for absorption in the gastrointestinal tract.
• Sucrose or maltose: Both are sugars requiring enzymes for digestion into simple sugars for absorption.
• Histamine and tyramine: These are substances created in the fermentation process in aged cheeses, processed meats, beer, wine, vinegars, and soy sauce. They naturally occur in some foods as well.
• Salicylate: This is a salt contained in some foods and is used to make aspirin.
• Tartrazine: This is an artificial food color used in food.
• Benzoates, butylhydroxyanisol (BHA), butylhydroxytoluene (BHT), sulfites: These are preservatives added to foods.
• Monosodium glutamate (MSG): This is a naturally occurring or added flavor enhancer in foods.
• Other food dyes: These are color additives used in food.
Resources, Tips for Clients
• Join The Food Allergy & Anaphylaxis Network (www.foodallergy.org) and encourage your patients to do the same. Silverman says, “This is an invaluable resource for professionals and patients to understand food allergy and intolerance. Whether you have an allergy or intolerance, the treatment is similar, and this organization gives you the support and research you need when diagnosed.” In addition, the American Academy of Allergy, Asthma & Immunology is the largest professional organization devoted to research and treatment of allergic disease and is worth investigating.
• Teach all clients with suspected food allergies or intolerances to be diligent about reading food labels and learn which ingredients are a potential problem. Encourage clients to call companies if they have specific questions about the safety of certain ingredients. Dietitians also should contact companies with questions.
• Encourage clients to call ahead before dining out to assess how accommodating a restaurant will be with their food allergy or food intolerance. Some restaurants post their menus online for review. At the restaurants, be proactive and ask servers how meals are prepared and whether they can make adjustments as needed.