Get full access to Outside Learn, our online education hub featuring in-depth nutrition, fitness and adventure courses, and more than 2,000 instructional videos when you sign up for Outside+..
Is your health an ongoing mystery, with multiple unexplained ailments such as skin problems, digestive disorders, anxiety, depression, and more? You could have food sensitivities. About one-third of Americans report having at least one food allergy, but a recent study showed that number may actually be as low as 1-3 percent. The truth is, true food allergies aren’t that common. Sensitivities and intolerances, however, are fairly prevalent. Here’s how they differ:
True food allergies are specific immune-system reactions to a particular food protein. Depending on an individual’s level of sensitivity, allergies can be triggered even by smelling or touching the offending food. Almost all true allergies are caused by the “big 8” foods: wheat, eggs, soy, milk, peanuts, tree nuts, fish, and shellfish.
Symptoms of food allergies tend to be immediate, and can result in reactions ranging in severity from mild to life-threatening. The most severe-but rare- reaction is anaphylaxis, which causes hives, breathing difficulties, and swelling of the throat. It’s uncommon, and occurs in fewer than 70 people per 100,000.
Food allergies are usually divided into immunoglobulin E (IgE)-mediated and non-IgE reactions. In an IgE-mediated reaction, the immune system identifies a particular food as an invader. It responds by producing IgE antibodies, which cause a release of histamines, chemicals that cause itching, inflammation, and other symptoms of an allergic reaction. IgE-mediated allergic reactions tend to be more immediate in onset, within minutes to a few hours after exposure.
Non-IgE reactions are caused by different immune-system responses, and are believed to involve the body’s T-cells. They are typically delayed in onset, and generally manifest 4-28 hours after contact with the offending foods. Non-IgE reactions may include abdominal pain, vomiting, diarrhea, and irritability.
Also called metabolic food disorder, food intolerances occur when you can’t metabolize certain components in food, often because the body lacks a particular enzyme to digest that food. The most common example is lactose intolerance, in which the digestive system cannot process lactose, the primary sugar in dairy products. Symptoms of a food intolerance are usually gastrointestinal, and may include gas, bloating, nausea, diarrhea, cramping, or heartburn. The immune system isn’t involved, and exposure to the offending food isn’t directly life-threatening. In many cases, food intolerances are secondary to other gastrointestinal disorders, and often resolve when the GI tract is treated.
Like allergies, food sensitivities involve an adverse reaction to certain foods; unlike true allergies, however, the immune system isn’t involved. Sensitivities are much more common than allergies, and often include symptoms such as nausea, bloating, headaches, joint pain, or rashes.
Food sensitivities include food idiosyncrasy, an adverse reaction to food that occurs through unknown mechanisms. Symptoms may resemble those of an allergy, ranging from mild to severe. The most common examples include sulfite-induced asthma or food-associated migraine headaches. Another type of sensitivity is an anaphylactoid response (not the same as anaphylaxis)-like a true food allergy, this involves the release of histamines, but does not involve the immune system.
True food allergies are probably caused primarily by genetic factors. The causes of food sensitivities and intolerances are less clear, and probably multifactorial. But most people agree that gut issues are at the root of most sensitivities and intolerances.
One underlying cause: increased intestinal permeability, or “leaky gut.” The theory is, the gut wall develops tiny holes from a variety of factors; these small holes allow larger, undigested proteins, yeast, pathogens, and other toxins to slip through the gut wall and into the bloodstream. These are perceived by the body as foreign invaders, and the immune system launches an attack.
Leaky gut is thought to be caused by antibiotic overuse and a consequent imbalance in gut bacteria; chronic use of ibuprofen and other NSAIDs; excessive alcohol consumption; allergenic foods, especially wheat and gluten; and stress. No longer considered controversial, the theory of leaky gut is now gaining notice from mainstream physicians.
Signs & Symptoms
Generally, we think of food sensitivities as causing gastrointestinal problems, gas, bloating, and indigestion. But food sensitivities may be the cause of dozens of unexplained maladies, ranging from eczema and dark circles under the eyes to joint pain, weight gain, irritability, depression, and even schizophrenia. Everyone responds differently to food sensitivities, but there are five telltale symptoms:
1. Weight gain. Food sensitivities trigger inflammation, and may contribute to insulin resistance, fatty liver, and higher insulin levels, promoting fat storage. Several studies have shown a link between inflammation and obesity; in one study, overweight children had higher levels of inflammatory markers and IgE antibodies,indicating food sensitivities and allergies.Other studies have shown that when mice were fed the equivalent of an American diet-high in gluten, dairy, soy, and other foods likely to trigger sensitivities-they produced more LPS, a bacterial toxin that promotes inflammation.
2. Moodiness and brain fog. Food allergies and sensitivities can impact the central nervous system, causing irritability, slowed thought processes (“brain fog”), anxiety, depression, fatigue, and more serious disorders. Many studies have proven this link. In one study of children with ADHD, almost 80 percent had food sensitivities. When offending foods were removed, their symptoms of ADHD dramatically improved.
3. Joint pain. Inflammation caused by food sensitivities can lead to joint pain, swelling, stiffness, and lack of mobility. Certain foods, especially nightshade vegetables (tomatoes, potatoes, eggplants, and peppers) tend to be especially aggravating in some people. These foods contain a compound called solanine that triggers arthritis and joint pain. Some people are also sensitive to lectins-sticky proteins found in grains, legumes, dairy, and nightshades that can promote joint pain.
4. Skin issues. Eczema, acne, rashes, dark circles under the eyes, and prematurely wrinkled or sagging skin are common signs of food sensitivities. Inflammation caused by food sensitivities can cause breakouts and skin rashes, and high levels of cortisol-triggered by the body’s ongoing stress response to aggravating foods-lead to a breakdown of collagen, the compound that keeps skin plump and firm.
5. Headaches. Chronic, low-grade headaches and migraines are well-known symptoms of food sensitivities and allergies. Certain compounds, such as sulfites (found in wine and dried fruits) and monosodium glutamate (MSG), are common causes of headaches in people who are sensitive. Nitrates and nitrites in processed meats such as salami and bacon, and foods high in tyramine (aged cheese, processed meat, olives, pickles, and nuts) can also trigger headaches if you’re sensitive to them.
Supplements for Sensitivities
Supplements and herbs that aid digestion, reduce inflammation, and heal the gut can help treat food sensitivities, allergies, and intolerances. Read labels carefully to be sure the supplement you’re choosing doesn’t include ingredients you’re sensitive to, such as dairy, soy, or shellfish. Some to try:
Betaine HCl. Low levels of stomachacid (hydrochloric acid) can lead to improper digestion and possible sensitivities and intolerances. Betaine HCl supplements can help boost stomach acid for better digestion. Take them after, not before or during, meals.
Digestive enzymes. Insufficient enzymes can provoke food sensitivities and intolerances; look for enzyme supplements that contain protease, lipase, and amylase, to digest protein, carbohydrates, and fats. Take them during meals.
Probiotics. Also called beneficial bacteria, they help treat food allergies, sensitivities, and intolerances by fighting harmful bacteria and increasing friendly bacteria in the gut. Studies also show that probiotics reverse increased intestinal permeability (leaky gut). Look for a broad-spectrum probiotic, with at least 6 different strains. Probiotic formulas that contain prebiotics in the form of inulin or FOS can exacerbate symptoms in some people, so you may want to avoid them until your gut is healed.
Quercetin, a flavonoid found in onion, apples, green tea, and red wine, has anti-inflammatory effects and can reduce reactions to compounds that trigger allergic reactions. Some studies also suggest that quercetin can enhance gut barrier function and heal leaky gut, a leading cause of food sensitivities.
Multivitamins. Because your digestion may be compromised, and you’re probably avoiding certain foods, multivitamin and mineral supplements can help fill in nutritional gaps. If you’re lactose intolerant, consider an additional calcium and vitamin D supplement.
Vitamin C. This safe, multi-purpose antioxidant is a good treatment for allergensin general. That’s because allergic symptoms are caused when mast cells produce histamines and other chemicals, and vitamin C helps mitigate the release of these chemicals. As an antioxidant, it can also help repair cellular damage.
TESTING 1, 2, 3
Tests that measure IgE levels can help diagnose a true food allergy. For many years, the gold standard was a simple blood test, like the ELISA or RAST tests, that measured IgE levels in the body. But because blood tests can produce false-positive results in people who already have elevated IgE levels (such as those with asthma or eczema), they have their shortcomings, and aren’t ideal as the sole method of diagnosing an allergy.
Other tests that can complement the standard blood test:
Skin prick test-This is done in a doctor’s office, and involves inserting a small amount of specific allergens under the skin. If a rash, bump, or swelling occurs, it often indicates a food allergy.
Food Elimination-challenge Diets-These are the gold standard for detecting adverse food reactions. They are difficult, because they require strict compliance, but can be extremely effective in diagnosing an allergy. In the elimination phase, one or several foods are removed from the diet according to a specific schedule, to see if the allergic symptoms disappear. The challenge phase involves foods being gradually reintroduced, to determine how much of that food is necessary for triggering an immune response.