Food intolerance is a detrimental reaction to a food, beverage, food additive, or compound found in foods. This compound produces symptoms in one or more of the body’s organs or systems. The term “food intolerance” generally refers to reactions in the body other than the symptoms produced by food allergies. Food hypersensitivity is used to refer broadly to both food intolerances and food allergies.
Food allergies are immune reactions, typically an IgE reaction caused by the release of histamine but also encompasses non-IgE immune responses. This process causes reactions within a few minutes to a few hours to foods.
Food intolerances can be classified according to the system in which they are associated. Intolerances are the result of the absences of specific chemicals or enzymes needed to digest a food substance. An example is hereditary fructose intolerance. Which may be a result of the body’s inability to absorb nutrients, this also occurs in fructose malabsorption. Food intolerance is a reaction that can occur with naturally occurring chemicals in foods, as in salicylate sensitivity. Drugs sourced from plants, such as aspirin, can also cause these kinds of reactions.
Reactions to chemical components of the diet are more common than true food allergies. They are caused by various organic chemicals occurring naturally in a wide variety of foods, both of animal and vegetable origin and less commonly by food additives, preservatives, colorings and flavorings, such as sulfites or dyes. Both natural and artificial ingredients may cause adverse reactions in sensitive people if consumed in sufficient amounts. The degree of sensitivity varies between individuals.
Pharmacological responses to naturally occurring compounds in food or chemical intolerances, can occur in individuals from both allergic and non-allergic family backgrounds. Symptoms may begin at any age, and may develop quickly or slowly depending on the individual. Triggers may range from a viral infection, illness or even an environmental chemical exposure. It occurs more commonly in women, which may be because of hormone differences. This may be because many food chemicals mimic hormones.
A deficiency in digestive enzymes can also cause some types of food intolerances. Lactose intolerance is a result of the body not producing sufficient lactase to digest the lactose in milk. Dairy products which are lower in lactose, such as cheese, are less likely to trigger a reaction in this case. Another carbohydrate intolerance caused by enzyme deficiency is hereditary fructose intolerance.
Celiac disease, an autoimmune disorder caused by an immune response to the protein gluten; results in gluten intolerance and can lead to temporary lactose intolerance. The most widely distributed naturally occurring food chemical capable of provoking reactions is salicylate, although tartrazine and benzoic acid are well recognized in individuals who are susceptible. Benzoates and salicylates occur naturally in many foods, including fruits, juices, vegetables, spices, herbs, nuts, tea, wines, and coffee. Salicylate sensitivity causes reactions to not only aspirin and NSAIDs but also foods in which salicylates naturally occur, such as cherries. Other natural chemicals which commonly cause reactions and cross reactivity include amines, nitrates, sulfites and some antioxidants. Chemicals involved in aroma and flavor are often suspect.
The classification or avoidance of foods based on botanical families bears no relationship to their chemical content and is not relevant in the management of food intolerance. Salicylate-containing foods include apples, citrus fruits, strawberries, tomatoes, and wine, while reactions to chocolate, cheese, bananas, avocado, tomato or wine point to amines as the likely food chemical intolerance. Thus, exclusion of single foods does not necessarily identify the chemical responsible as several chemicals can be present in a food. A patient may be sensitive to multiple food chemicals and reactions are more likely to occur when foods containing the triggering substance are eaten in a combined quantity that exceeds the patient’s sensitivity thresholds. People with food sensitivities have different sensitivity thresholds, and so more sensitive people will react to much smaller amounts of the substance.