Food intolerance is a reproducible adverse reaction to a food or food chemical. Food intolerance can affect any system of the body, commonly the skin (e.g. rashes, excema), gastrointestinal (e.g. pain, changes to bowel habits, bloating), respiratory tracts (e.g. sinus issues, mucous production, tightening of airways), and the central nervous system (e.g. mood disturbance, fuzzy head, poor concentration, fatigue, migraines). Reactions can range from mild to severe and can occur occasionally or ongoing. Reactions can also occur up to three days after eating a trigger. Plus there is usually a tolerance level, meaning that you may feel okay after eating a small amount, but not feel well eating more than your personal tolerance level. This makes investigating food intolerance without assistance by a specialist practitioner difficult.
The main differences between a food intolerance and Irritable Bowel Syndrome (IBS) is that IBS is limited to the digestive tract i.e. symptoms usually involve abdominal bloating and /or pain, cramping, reflux, indigestion, diarrhoea, loose stools and / or constipation. More systemic symptoms such as involving the skin and nervous system can indirectly occur from associated 'leaky' / permeable gut. Read more about IBS here.
Food intolerances are different to food allergies. An allergy causes an immune system reaction soon after eating or with exposure to the skin. Allergy can cause severe and life threatening symptoms (anaphylaxis) that require immediate medical attention. These symptoms include difficultly breathing, swelling of the tongue and throat, persistent coughing, difficultly talking, pale skin and limp body. Mild allergy symptoms include swelling of the face, eyes and /or lips, welts / hives on the skin, abdominal pain and/or vomiting. Less common food allergy symptoms include colic, eczema, reflux, chronic diarrhoea and failure to thrive in infants.
Food Protein Intolerance
Common food intolerances include to proteins found in many popular foods - whey or casein in dairy, gluten in some grains, soy and eggs. People can also experience a range of symptoms from many other different food proteins especially when the gut has become permeable (aka leaky). In this case, food proteins 'leak' through the small intestine into the blood and trigger an immune system attack - causing inflammation and a range of symptoms.
Please speak with your Doctor if you think you or your child has a food protein intolerance. You may be referred to a specialist who can conduct skin prick testing.
In some cases, depending on your symptoms, a food protein intolerance investigation involves eliminating the suspected food/s for a period of time and then reintroducing to understand their impact.
Food Chemical Intolerance
To many people’s surprise, food chemicals not only include those added during food processing (e.g. preservatives, colours and flavour enhancers such as MSG), but can be naturally occurring in a wide range of natural foods like fruits and vegetables (e.g. salicylates, amines, glutamate, oxalates, lectins and others). Food proteins such as gluten, whey and casein (in dairy), and others found in soy, eggs and other foods can also be problematic for sensitive people.
Lactose Intolerance & Other FODMAPs
On average, 65% of people are lactose intolerant (sometimes referred to as lactose malabsorption). Lactose is a double sugar molecule made up of both glucose and galactose. It is found in animal (and human) milk and milk products, yoghurt and some cheeses. When eaten, lactose required the enzyme lactase to break the sugar molecules up for absorption. If someone has a reduced production of the lactase enzyme, they will experience an increase in fluid throughout the bowel and the symptoms of osmotic diarrhoea. People with a sugar malabsorption (lactose, glucose, fructose, sorbitol, mannitol and other FODMAPs) will have varying sensitivities and will tolerate different amount of the sugars. This can be investigated by dietary experimentation and breath testing.
The production of digestive enzymes such lactase reduces with age. Different ethnicities also have greater risk of intolerances. A treatment with antibiotics can also result in acute lactose intolerance, as can injury to intestinal mucosa from several infections, inflammation or other gastrointestinal diseases. Such conditions include gastroenteritis, Inflammatory Bowel Diseases, Coeliac disease and chemotherapy.
Read more about FODMAPs symptoms and the Low FODMAPs Diet here