Few food trends have become so pervasive, and so quickly, as the gluten-free movement. Less than 10 years ago, celiac disease was a mere blip on the radar of mainstream media.
Then, TV personality Elisabeth Hasselbeck published The G-free Diet (Center Street 2011), President Bill Clinton promoted his post-heart-surgery gluten-free diet on “The Ellen DeGeneres Show,” Paleo and Wheat Belly(Rodale Books 2014) hit the scene, and a billion-dollar industry was born.
At the time, the scientific community accepted celiac disease as the only adverse reaction to gluten — despite that individuals who tested negative for the autoimmune disease were reporting celiac-like symptoms (“foggy mind,” depression, ADHD-like behavior, abdominal pain, bloating, diarrhea, constipation, headaches, bone or joint pain and chronic fatigue). Eventually new research suggested a spectrum of non-celiac gluten-related disorders that improve when gluten is removed from the diet — now known as non-celiac gluten sensitivity or non-celiac wheat sensitivity.
Today, adults in the U.S. are increasingly self-reporting food allergies without a diagnosis from a doctor. Consumers around the globe are experimenting with elimination diets as a means to identify causal association with symptoms ranging from gut distress to joint pain, lethargy or depression.
Most health practitioners, and registered dietitian nutritionists in particular, do not advocate unnecessary restrictive dieting. Nonetheless, many consumers are finding relief through elimination diets — and the scientific community isn’t sure why.
Confusion over what causes certain responses to foods is a culmination of heated debate among medical researchers, vague terminology with conflicting definitions, gaps in research and, arguably, the inherent discomfort of “the unknown.”
Let’s Start with the Known
A food allergy exists when exposure to a specific food results in an adverse response in the immune system. Because a one-time reaction is not definitive, a criterion for a food allergy is that the immune response be reproducible.
Symptoms range from mild itching and hives to severe anaphylaxis, which can cause difficulty breathing, dizziness, loss of consciousness or death.
Most food allergies are IgEmediated, meaning the immune system identifies an allergen as an “invader” and overreacts by producing antibodies called immunoglobulin E. However, some food allergies — such as eosinophilic GI disease and protein-induced enterocolitis — are not IgE-mediated.
A food intolerance refers to malabsorption in the digestive tract and does not involve the immune system. The inability to break down certain foods may be the result of enzyme deficiencies or reactions to naturally occurring chemicals in foods. Unlike food allergies (in which even a microscopic morsel of an allergen can cause an adverse reaction), food intolerances are dose dependent: the more one eats of the offensive food, the worse the symptoms — usually along the lines of nausea, stomach pains, vomiting and diarrhea.
Here is Where it Gets Tricky
There also appear to be adverse food reactions that do not fit current diagnostic criteria for food allergies or food intolerances. Some practitioners refer to these as food sensitivities; however, food sensitivity has no universally accepted definition — and to compound confusion, the term has different meanings, depending on who you ask.
For example, the American Academy of Allergy, Asthma and Immunology uses “food sensitivity” interchangeably with intolerance. According to the Guidelines for the Diagnosis and Management of Food Allergy in the United States, the term “food hypersensitivity” often is used to describe food allergies, while other groups use “food sensitivity” as an umbrella term that includes both allergies and intolerances. And a 2012 study in the Canadian Medical Association Journal defines “food sensitivity” as “a nonspecific term that can include any symptom perceived to be related to food and thus may be subject to a wide range of usage and interpretation.”
These mysterious non-allergic adverse food reactions have many practitioners perplexed.
For example, take sulfite sensitivity, which is more common in people with asthma, especially those taking steroid medications. Reported symptoms include respiratory reactions and asthma, hypotension, GI reactions, dizziness and hives. Currently there are no validated lab tests to diagnose a sulfite sensitivity and the mechanism is yet to be determined. Medical history, symptom diaries and controlled exposure to test for reactions (known as an oral challenge) are used to make the diagnosis.
Other reports of triggers for adverse food reactions run the gamut, including various fruits and vegetables, grains, protein foods and dairy. Often these cases have already gone through allergy testing, excluded GI health conditions and exhausted diagnostic processes by physicians, including general practitioners, endocrinologists, gastroenterologists and allergists.
Debra Indorato, RDN, LDN, CLT, a nutrition and food management consultant in Tampa, Fla., has specialized in food allergies for nearly 30 years. It was early in her career when some of her referrals experienced persistent symptoms, even after testing negative for food allergies, and she began researching food sensitivities and immunology. Her personal working definition for food sensitivity is “a nonallergic inflammatory reaction that can affect any area of the body.” But identifying such a broad, enigmatic occurrence of inconsistent, overlapping symptoms is a challenge.
Food allergy assessment tools — skin pricks or the double-blind, placebo-controlled food challenge — are not applicable for these cases since allergic reactions are immediate and often dramatic, while “food sensitivities” are delayed and hit-or-miss. Carbohydrate intolerances, such as lactose intolerance, can be diagnosed with a hydrogen breath test or fecal test, while blood tests, endoscopies or biopsies may be used to rule out other conditions.
In an attempt to identify specific foods to which individuals are sensitive, medical testing companies have developed various proprietary blood panels. Some measure antibodies in the blood, such as the “IgG test” (which, since IgG is a “memory antibody,” actually only confirms exposure to a food, not a reaction to it). Others are centered on studying white blood cells as an indication of an inflammatory response — including the Alcat test and the enzyme-linked immunosorbent assay, or ELISA.
Recently, the mediator release test, or MRT, has gained favor among some practitioners, including a segment of registered dietitian nutritionists who then implement the Lifestyle Eating and Performance, or LEAP, diet based on the assay results. The MRT measures levels of cytokines, histamine, leukotrienes, prostaglandins and other mediators released from white blood cells after exposure to 150 foods and food chemical profiles. MRT supporters cite evidence indicating correlations between the immune system mediators, ensuing inflammation and risk of chronic disease such as osteoporosis and cardiovascular disease, as well as other conditions including GERD and cognitive decline. But while there is plenty of anecdotal vouching for MRT’s effectiveness in identifying potential sensitivities, there are no peer-reviewed, published studies validating the test.
Laura Matarese, PhD, RDN, LDN, CNSC, professor at the Brody School of Medicine at East Carolina University and co-editor of The Health Professional’s Guide to Gastrointestinal Nutrition (Academy of Nutrition and Dietetics 2013), says that in addition to the lack of research, there also is no consensus or endorsement of food sensitivity panels by any allergy or immunology organizations, noting that most insurance companies will not cover them.
Janice Vickerstaff Joneja, professor at the School of Family and Nutritional Sciences at the University of British Columbia and author of The Health Professional’s Guide to Food Allergies and Intolerances (Academy of Nutrition and Dietetics 2014), also is an MRT skeptic. However, she says the elimination and challenge components of LEAP therapy are useful.
Los Angeles-based consultant Christine Bou Sleiman, MS, RDN, CLT, has been a certified LEAP therapist since 2016 and experienced significant improvements in her own digestive health and inflammatory skin disorder since following the immune-calm LEAP protocol. “The MRT gives us a starting point, rather than taking a stab in the dark,” she says, “especially when many of these referrals are already on some form of elimination diet.” Bou Sleiman adds that she sees profound symptom relief in her clients and often helps increase the variety of foods in their diets.
Still, Emily Fonnesbeck, RD, CD, CLT, says that practitioners need to understand clients’ underlying issues, such as disordered eating, that may be exacerbated by an elimination diet. Before she suggests food sensitivity testing, Fonnesbeck works with new clients to identify potential causes of the symptoms and address primary issues, such as the stress caused by not being able to pinpoint why they don’t feel well.
“Even for clients who feel better on the elimination diet, it is difficult to know exactly why they are seeing benefits,” Fonnesbeck says. After all, the virtue of being more mindful about eating may in itself help ease physical symptoms.
A study in the journal Social Science and Medicine explored the perspectives of British general practitioners when confronted with patients who believe they are experiencing adverse reactions to certain foods. Although working with the patients’ beliefs was seen as important to preserving the doctor-patient relationship, skepticism among the physicians was strong.
However, it was “tempered by an element of self-awareness and an awareness of the limitation of modern medicine,” wrote the authors. “With the transitional nature and constant evolution of medical knowledge, several of the participants entertained the idea that this condition might be recognized and understood in the future.”