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The 7 Most Common Food Intolerances

Learn what symptoms to look out for and which foods to avoid

Food intolerances are on the rise and 30% of people in the UK and Ireland believe they are intolerant to one or more foods.

This is largely due to modern day farming and manufacturing, overconsumption of processed foods and increased exposure to toxic chemicals and ingredients in food.

Discover the 7 most common food intolerances, symptoms to look out for and how to test for food intolerances. Learn which foods to avoid and how to manage food intolerances by supporting the body naturally.

What is a food intolerance?

A food intolerance is an adverse reaction to eating a particular food that the body finds hard to digest. Symptoms usually occur a few hours after eating the food and include:

  • Bloating and flatulence
  • Stomach pain or cramps
  • Nausea
  • Vomitting
  • Diarrhoea
  • Heartburn
  • Irritability or nervousness (jittery)
  • Headaches or migraines

What causes food intolerances

Food intolerances are often caused by multiple factors including:

  • A lack of digestive enzymes which are necessary to break down certain foods such as lactose in dairy.
  • Eating junk food and processed foods which contain additives, preservatives, artificial colourings and flavourings. These toxic ingredients are known to cause allergies and wreak havoc with your health.
  • Chemicals and toxins in food and the environment (air, water, soil).
  • Coffee and alcohol, both of which cause inflammation and aggravate the gastrointestinal system.
  • High histamine foods and drinks such as pickled and cured foods (ham, deli meats), alcohol and dried fruits.
  • The early introduction of foods to babies when their digestive systems are sill underdeveloped.
  • Reduction in breastfeeding. Breast milk contains five different types of antibodies (immunoglobulins) that help support the baby’s immune system and the prevention of allergies. Intolerances to cow’s milk products are one of the most common food intolerances.
  • Medications including over-the-counter anti-inflammatory drugs and antibiotics. They destroy beneficial gut bacteria which negatively impacts digestion and gut function, making you more susceptible to intolerances.

The difference between a food intolerance and a food allergy

The difference between a food intolerance and a food allergy is the way the body responds. When someone has an allergic reaction to eating a particular food, their immune system will mount a response which is called an IgE mediated hypersensitive reaction. Food allergies can be life threatening; symptoms are often severe and occur almost immediately after eating the food. In addition to causing gut-related symptoms, someone may also experience hives, rashes, dizziness, tongue swelling, itchiness, airway closure and anaphylaxis. Food intolerances are non-life-threatening and do not involve the immune system. With a food intolerance, the digestive system triggers the response (hence the gut-related symptoms that occur) and symptoms tend to happen a few hours after eating the food.

How to test for food intolerances

IgE mediated food allergies can be detected using either a skin prick test or a blood test. During a skin prick test, the clinician will place the potential food allergen (for example dairy) on the skin and then prick the skin to see if a reaction occurs (a swollen lump or weal). A blood test measures the amount of IgE antibodies in the blood after eating a particular food allergen.

To identify if a food intolerance is present, practitioners tend to use a food diary and an elimination and reintroduction protocol. This involves noting down all the food you have eaten and recording any symptoms that occur. Any foods thought to be causing a reaction should then be eliminated for a period of time (usually 6 weeks to 3 months). If your symptoms improve after eliminating the food but appear again after reintroducing the food, you’re likely to be intolerant to that particular food.

There are a number of food hypersensitivity tests available (also skin prick tests) that look at elevated IgG levels in the body. They test up to 100 different types of foods to see if IgG levels increase when a food is eaten. These tests haven’t been scientifically proven so there is a question mark around whether or not they provide reliable results as many adults and children produce IgG antibodies despite not showing any symptoms.

Other ways to test for food intolerances include:

  • Nambudripad’s Allergy Elimination Technique (NAET) which is a non-invasive, natural solution for detecting and treating allergies and intolerances. It uses a combination of kinesiology, acupuncture, acupressure, energy balancing, spinal manipulation and nutritional medicine.
  • Bio-resonance therapy uses technology that scans the body to detect any imbalances in the human bio-field and adjust the body’s energy patterns. It aims to fine-tune the body and stimulate organs that are under-functioning.
  • Kinesiology is very useful for testing and treating intolerances and allergies. It is a muscle-testing technique that practitioners use to test how the body responds to foods, herbs and supplements. A muscle “weakness” in response to a particular food would indicate there is an intolerance or allergy present.

If you think you may have a food allergy or intolerance, speak to your natural health practitioner who will be able to advise you accordingly regarding testing and best approach forward.

Types of food intolerances

  1. Gluten intolerance occurs when you react to the gluten protein molecules (gliadin and glutenins) in wheat, rye, spelt and barley. Gluten is also hidden in lots of foods such as pasta sauces, condiments, salad dressings, meat/fish alternatives and snack foods. Learn more about gluten intolerance.
  1. Lactose intolerance happens when the body struggles to digest lactose which a naturally-occurring sugar found in milk and dairy products (cheese, yoghurt, ice cream). People with lactose intolerance do not produce enough of an enzyme called lactase which is made in the small intestine. Learn more about going dairy-free. 
  1. Salicylate sensitivity is a reaction to foods that contact salicylates or salicylic acid which is a natural compound found in many fruits, vegetables and spices. The foods that contain high amounts of salicylates include apples, avocados, blueberries, cherries, grapefruit, dates, kiwi fruit, mushrooms, cauliflower, cucumber and alfalfa sprouts. Coffee and peppermint tea also contain lots of salicylates.
  1. Amines are chemicals that naturally occur in the breakdown of protein in foods. Higher levels of amines are found in high protein foods (meat, fish and dairy), fermented foods, ripened fruits (especially bananas and tomatoes), charred, grilled or over cooked foods. There are specific enzymes in the gut that help break down amines. A deficiency in these enzymes causes amines to build up which can trigger allergic reactions in some people.
  1. Sulphites (also known as sulphur dioxide) are commonly used in wines and foods as a preservative as they have antioxidant and antibacterial properties, helping to maintain freshness and prevent oxidation. Foods that contain sulphites include dried fruits, canned/frozen fruits and vegetables, jams/ preserves and fruit juices. In some people, sulphites can cause an allergic reaction or intolerance whereby they experience hives, hay fever, headaches, wheezing and asthma-like symptoms. This is due to a lack of the enzyme sulphite oxidase that helps break down sulphur dioxide in the body.
  1. FODMAPS intolerance is an inability to digest high FODMAPS foods thus causing uncomfortable gut symptoms like abdominal pain, cramping, bloating, diarrhoea and constipation. FODMAPS refers to fermentable oligosaccharides, disaccharides, monosaccharides and polyols; these are particular types of carbohydrates in foods (the sugars, starches and fibre). Poor absorption of FODMAPS can make the small intestine absorb more water and cause food to ferment in the colon. High FODMAPS foods include wheat, onion, garlic, apples, apricots, cherries, figs, mangoes, peaches, plums, asparagus, Brussels sprouts, cauliflower, artichokes, legumes, pulses, dairy and sweeteners.
  1. Fructose intolerance, also called fructose malabsorption, occurs when the digestive system isn’t able to efficiently break down fructose. Fructose is a naturally-occurring sugar found in fruit, some vegetables and honey. Table sugar also contains fructose and fructose is used as a sweetener (high-fructose corn syrup) in processed foods, sweets and drinks. Causes of fructose intolerance include an imbalance of beneficial gut bacteria, stress, inflammation in the gut, IBS and eating too many processed or refined foods.

How to manage food intolerances

  • Consult with a nutritional therapist or naturopath who will be able to take a full case history from you, request and assess relevant tests, and advise you on the best approach for managing your food intolerances.
  • Keep a food diary and eliminate culprit foods. Note down everything you’re eating and any symptoms that occur afterwards. If you’re reacting to particular foods, it’s best to avoid these foods until you get to the root cause of your intolerances.
  • Heal and restore your gastrointestinal system by reducing inflammation of the gut lining and repopulating the gut with probiotics (beneficial gut bacteria). Herbs including Aloe vera, Slippery elm, Turmeric and Licorice root are excellent for healing mucous membranes, improving digestion and decreasing inflammation.
  • Digestive enzymes help the digestive system to break down food and absorb nutrients more efficiently. Many food intolerances are caused by specific enzyme deficiencies (such as lactase) so taking a supplemental enzyme can help reduce or eliminate symptoms.

Avoid adverse food reactions

Particular foods trigger an adverse reaction in the gut that can lead to uncomfortable symptoms such as bloating and gas, headaches and irritability. A lack of digestive enzymes, poor gut function and compounds in certain foods are linked to food intolerances. If you suspect you have a food intolerance, start a food diary and seek the help of a natural health practitioner as soon as possible.

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