Definition

Food intolerance is a digestive reaction to foods that are irritating or difficult to digest, resulting in improper digestion. Nearly everyone experiences food intolerance at some point. Some individuals have specific intolerances, such as lactose intolerance, which affects 10% of Americans.

The symptoms of food intolerance and food allergies can be similar, making it difficult to differentiate between them. Food intolerances are more common than allergies. Unlike food allergies, people with food intolerances can usually consume small amounts of the offending food without symptoms, whereas those with food allergies cannot tolerate even small quantities. However, consuming large amounts of a food that triggers intolerance can exacerbate symptoms depending on the quantity consumed. Unlike allergies, food intolerances do not involve an immune response and are not life-threatening.

Causes

Food intolerance can arise from various factors, including:

• Insufficient enzymes to digest certain foods. A notable example is lactose intolerance, which occurs when the body lacks the enzyme lactase.
• Sensitivity to specific preservatives, such as sulfites, which are commonly used in dried fruit, canned foods, and wine, and can provoke adverse physical reactions in some individuals.
• Irritable bowel syndrome (IBS), a chronic condition characterized by symptoms such as abdominal cramping, constipation, and diarrhea.
• Stress and psychological factors, which can cause negative reactions to certain foods, although the exact mechanisms are not yet fully understood.
• Reactions to toxins, including food poisoning or toxins from scombroid fish.

Common foods that lead to intolerance include dairy products, gluten (a protein found in wheat and other grains), caffeine, amines, fermented foods, sulfites (used as preservatives), and fructose. Additionally, salicylates, commonly used as pesticides, can trigger intolerance, as can substances like eggs, monosodium glutamate (MSG), food coloring, alcohol, and aspartame (an artificial sweetener).

Risk Factor

Although general risk factors for food intolerance are not well-documented in the literature, certain factors are known to increase the risk of intolerance to specific substances, such as lactose. These include:

• Age: Lactose intolerance is more commonly seen in adults than in infants or children.
• Prematurity: Premature infants often have lower levels of lactase, as their small intestines are not fully developed.
• Small intestine diseases: Conditions affecting the small intestine, such as celiac disease and Crohn's disease, may contribute to lactose intolerance.
• Cancer treatment: Chemotherapy may result in lactose intolerance as a side effect.

Symptoms

Symptoms of food intolerance may include:

• Nausea
• Abdominal pain
• Bloating, distention, cramps
• Vomiting
• Heartburn, a burning sensation in the throat
• Headaches
• Diarrhea

These symptoms typically emerge within hours of consuming the problematic food. Other conditions, such as irritable bowel syndrome (IBS), stress, inflammatory bowel disease (IBD), and food allergies, can produce similar symptoms.

Diagnosis

To diagnose food intolerance, the doctor will inquire about symptoms, suspect foods, preparation methods, whether others experienced similar symptoms, and any medications used to alleviate the symptoms. Symptoms usually develop a few hours after consuming the food. If they appear shortly after eating, it may suggest a food allergy.

Diagnosis of food intolerance is often achieved through trial and error, identifying which foods cause the symptoms. A food diary may be recommended to track the foods consumed and the symptoms that follow, helping to identify patterns.

Another diagnostic method is the elimination diet. By avoiding the suspected food until symptoms disappear, and then gradually reintroducing it while monitoring symptoms, food intolerance can be identified. However, it is essential to consult a nutritionist before starting an elimination diet to ensure that nutritional needs are met.

The diagnosis of food intolerance differs from that of food allergies. If a food allergy is suspected, tests such as skin prick tests and evaluations of IgE antibody levels will be conducted to confirm the diagnosis.

Management

Once food intolerance is diagnosed, your doctor and nutritionist will work together to help you temporarily reduce the consumption of specific foods. If eliminating particular foods alleviates symptoms, you may later be advised to limit your intake of other foods with similar components. Food elimination should be done temporarily and under close supervision to avoid long-term nutritional imbalances, especially in children.

Complications

People with food intolerances may experience nutritional deficiencies. For instance, individuals with lactose intolerance who completely avoid cow's milk might suffer from reduced calcium and vitamin D levels, which can be managed with appropriate supplements. It's essential to consult a doctor about this.

For those avoiding gluten, it is important to maintain a diet rich in fresh vegetables, fruits, and gluten-free high-fiber foods to meet fiber and essential nutrient requirements, such as B vitamins.

Food intolerances often persist throughout life, but most individuals can manage their symptoms by reducing the intake of foods that irritate their digestive system. While food intolerances cause discomfort, they do not pose life-threatening risks like food allergies do.

Prevention

To prevent food intolerance symptoms, consider the following:

• Learn which foods trigger symptoms of intolerance, and limit consumption to levels that do not cause discomfort.
• When dining out, inquire about the ingredients used in dishes, as some foods you cannot tolerate may not be listed on the menu.
• Familiarize yourself with reading food labels, checking for the composition, preservatives, and spices used.
• If you believe you are not intolerant to a particular food, try abstaining from it for a while, then reintroduce it in small amounts to test your tolerance.

When to See a Doctor?

It's crucial to consult a doctor if you experience persistent abdominal pain despite medication or food avoidance, severe diarrhea with possible signs of dehydration, or unexplained weight loss. If you suspect food intolerance in your child, consult a doctor before eliminating foods from their diet, as this could negatively affect their growth and development. For example, removing cow's milk, a source of calcium, vitamin D, and protein, without proper nutritional alternatives could have adverse effects.

Consult a doctor if your child shows signs of digestive issues, such as recurring abdominal pain or diarrhea, and:

• The child's growth is slower than that of their peers.
• There is no improvement after following a professionally recommended elimination diet.
• The child has severe reactions to specific foods.
• A food allergy is suspected.

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