Many people know that food allergies can cause hives, itching, eczema, nausea, diarrhea, and in severe cases, shock or constriction of the airways, which can make it difficult to breathe and can be fatal. But can certain foods and food additives also cause emotional, behavioral, or learning problems? You bet. These types of reactions are called “hidden” food allergies, and they could be hampering your efforts for a better body.

My patient Mark had ADD and symptoms of anxiety and depression. He explained that whenever he ate foods with MSG, he became violent. To see why this was happening, we scanned his brain twice—once having avoided anything with MSG and once after he ate a Chinese dinner laced with MSG. The MSG scan showed a marked difference in activity in Mark’s left temporal lobe, the area associated with temper control.

I told Mark he could either stay away from MSG or take medication to prevent the problem. To my surprise, he opted for the medication. He explained that if he lost his temper one more time, his wife was going to divorce him, and “you never know what has MSG in it. Sometimes it is listed on the label as natural flavorings.” If you have problems with your temper, you might want to hold the MSG.

Although Mark’s case is extreme, sensitivity to food additives, such as MSG, artificial sweeteners, or food colorings, is probably more widespread than we realize. As far as food allergies go, the most common culprits are peanuts, milk, eggs, soy, fish, shellfish, tree nuts, and wheat. These eight foods account for 90 percent of all food-allergic reactions. Other foods commonly associated with allergies include corn, chocolate, tea, coffee, sugar, yeast, citrus fruits, pork, rye, beef, tomato, and barley.

Physical symptoms that might tip you off to a food allergy or sensitivity include dark circles under the eyes, puffy eyes, headaches or migraines, red ears, fatigue, joint pain, chronic sinus problems (congestion or runny nose), or gastrointestinal issues. Behavioral problems that can be caused by foods include aggression, sleep problems, lack of concentration, and changes in speech patterns (turning into a motor mouth or slurring words).

When a food allergy or food sensitivity is suspected, a medical professional may recommend an elimination diet. An elimination diet removes all common problem foods for a period of one or more weeks. These diets aren’t easy to follow because they’re very restrictive. After the initial diet period, potential allergens are reintroduced one-by-one. Foods that cause abnormal behaviors or physical symptoms should be permanently eliminated from the diet. Working with a nutritionist may make a big difference.

Here’s how an elimination diet worked for a 37-year-old woman who complained of fatigue, anxiety, and panic attacks. When she went on the elimination diet, all of these symptoms disappeared. After reintroducing foods to her diet, she discovered that sugar, corn, cheese, and grapefruit caused her symptoms to flare up. Now, as long as she avoids these foods, she remains symptom-free.

In a 2008 study from Holland, researchers found that putting children with ADD on a restricted elimination diet reduced their symptoms by more than 50 percent in 73 percent of children. This is basically the same effectiveness as prescription ADD medication without any of the side effects.

During the study, the children could eat only rice, turkey, lamb, vegetables, fruits, margarine, vegetable oil, tea, pear juice and water. But the results were stunning. In this study the researchers also found that the children’s moods and oppositional behaviors were also improved.

In 2003, a SPECT study was performed to determine if eliminating problem foods could affect brain function. The study tested cerebral blood flow in 30 people with celiac disease (an intolerance for wheat and wheat products). Half of them had been following a gluten-free diet for almost one year while the other half had not eliminated gluten from their diet. Twenty-four healthy individuals were also tested as a control group.

Researchers concluded that the celiac patients who followed a gluten-free diet were significantly less likely to experience decreased cerebral blood flow than those who continued to eat gluten. Only 7 percent of the patients who eliminated gluten from their diet experienced lower blood flow in at least one area of the brain compared to 73 percent of those who continued to eat gluten showed reduced blood flow in at least one area of the brain. Once again, this shows that the foods you eat directly affect your brain.

In my practice, I’ve found that many adults and children with emotional, learning, or behavioral problems improve when they eliminate specific foods or food additives from their diets. In particular, I work with a lot of children who have autism or Asperger’s Syndrome. When I put these kids on a diet free of gluten (wheat, barley, rye, oats, and any products made from these grains) and casein (milk protein and all dairy products), I’ve noticed that some of their behavioral problems diminish and their language tends to improve.