When our immune system declares war on food, the entire body becomes the battlefield.

Our relationship with food is the longest relationship we have in our lives. Things don’t always go smoothly in relationships; the disagreements can be mild or severe. Although problems are usually resolved quickly, sometimes they can drag on for weeks, months or years, causing chronic distress.

When things are not going well between us and food, many parts of our bodies suffer. Unexplained pain, weight gain, fatigue, arthritis, headache, depression and many other conditions have been linked to ingesting food that is wrong for us. The symptoms, however, may be too vague for most people and even doctors to attribute to a strained relationship with food.

The negative reaction, whether quick and obvious or hidden and delayed, involves the immune system and is usually called a food allergy or sensitivity. When the immune system takes center stage in our conflict with food, its actions vary. Sometimes they are quick and easily recognized as an allergy, such as hives, rashes, swelling or even life-threatening anaphylaxis. Peanut allergy is a common example of such a reaction. The quick allergic reaction may happen only in the gut and lead to nausea, vomiting, abdominal pain and diarrhea. The victims—or their parents as this type of reaction often begins in childhood—may think they just have food poisoning when, in reality, it is an allergic reaction called gastrointestinal anaphylaxis.

In the case of food sensitivity, the immune system response is neither quick nor immediately obvious. It starts with inflammation that damages the wall of the intestine, reducing its ability to absorb valuable nutrients. The now “angry” immune system doesn’t always stop there. It now looks for “enemies” everywhere; its “foot soldiers” start attacking normal organs. Meanwhile, the damaged intestinal wall becomes leaky, allowing allergens and toxic substances to enter the bloodstream, spreading throughout the body, making the person sick and triggering even more immune system attacks and inflammation.

Some of the mechanisms of abnormal immune system reaction to ingested substances are better understood than others. Celiac disease is the best studied example of such an immune response going awry. In case of celiac disease, the immune system reacts to gluten or similar proteins found in common grains, such as wheat, rye and barley. The resulting inflammation in the intestine leads to malabsorption, gastrointestinal symptoms and can eventually damage virtually any organ in the body, including joints, skin, bones and the brain.

Although the most infamous, gluten is far from being alone in producing inflammatory responses. Cow’s milk is another major offender. While in some people it causes an instant allergic reaction, in many others it leads to chronic inflammation, the mechanism of which is not completely understood.

Many additional substances, including food that is normally considered healthy such as vegetables or fish, can trigger an abnormal immune system response. Because the reaction is delayed, the symptoms are not always typical; different individuals have their own unique immune response triggers. They may complain of fatigue or arthritis, or be diagnosed with premature osteoporosis or anemia. Attention deficit, lethargy, headaches and even gait disturbance have been shown to improve after elimination of certain foods from the diet. The true cause of health problems may go undiscovered for years while the person is unsuccessfully treated with multiple medications that cause their own slew of side effects.

Among less expected manifestations of food allergies is unexplained weight gain. While the exact mechanism of the connection is not fully understood, there are many reports of significant weight loss after elimination of reactive foods from the diet. A possible explanation is that inflammation in the intestines leads to nutrient depletion, food craving and overeating. At the same time, chronic fatigue caused by the body being in a constant state of war may lead to abuse of sugary drinks or coffee with caffeine in an attempt to boost energy.

How to Prevent the Damage

With so many people suffering from obvious and hidden food allergies, it is only natural to ask what we can do to prevent the damage. First and foremost, it is important to undergo a medical evaluation to make sure other treatable medical conditions are not missed. Identify foods that have already caused problems in the past—no matter how minor—and stay away from them. The body knows better and often sends early warnings.

It also helps to switch to a healthier balanced diet. That alone may be enough to keep many reactive foods off the menu and reduce the inflammation. In addition, get tested for food sensitivities. Test panels for up to 184 foods are available. While they may not always provide definitive answers, they may help narrow the search for the offending food or foods

Tests for nutrient deficiencies may indicate intestinal damage due to a hidden food allergy that needs to be further investigated. The uncovered deficiencies should be promptly corrected by proper diet and supplementation. It is also beneficial to get a comprehensive digestive stool analysis that includes markers for the presence of inflammation due to allergy and microbiome (bacteria living in the intestine) imbalance.

Consider probiotics if tests show intestinal microbiome imbalance. “Wrong” bacteria living in the intestines and even overgrowth of the normally “good” bacteria may produce substances triggering the immune system to produce inflammation. A test for bacterial overgrowth can be performed first to establish an initial baseline.

Food allergies should be taken seriously because even when the symptoms are not severe, the abnormal immune response to food is much more than just an inconvenience or a passing problem. Research has shown that long-standing inflammation in the intestines increases the chance of dying prematurely. Moreover, even after the intestinal inflammation improves or resolves following the removal of the offending food, the attacks of the immune system on other body organs may not go stop as quickly, if ever. It is therefore paramount to take action without delay whenever a food allergy is suspected.

Tatiana Fleischman, MD, is an internal medicine physician who is the founder and medical director of Integrative MD in Stamford. In addition to practicing internal medicine, she teaches her patients about nutrition, fitness, supplements, vitamins, herbs and stress management. Connect at 203-275-666, [email protected] or IntegrativeMDCenter.com.