Many people experience unpleasant reactions to foods they have eaten and suspect they have a "food allergy". However, only 2-5% of adults and 2-8% of children are truly "allergic" to certain foods.
The remainder of people may be experiencing food intolerance, or food sensitivity, rather than true food allergy.
I think a quick lesson is in order?
A food allergy occurs when an individual ingests a food (usually containing a protein) that the body sees as a "foreign" or threatening substance - known as an ANTIGEN or ALLERGEN.
The person's immune system responds by mounting an attack, producing large amounts of IgE antibodies, which attach themselves to specialised white blood cells. These cells release histamine and other inflammatory substances, producing "classic" allergic symptoms of swelling and inflammation. Conditions and symptoms such as rhinitis, asthma, wheezing, lip swelling, itchy skin, hives, and eczema involve this type of "allergic" reaction. The allergens involved could be anything from a food protein, pollen from flowers or grasses, house-dust mite or animal dander.
A food "intolerant" reaction also occurs when the body "reacts" to the ingestion of a food. This reaction however may or may not involve the immune system, and may be caused by a food protein, a starch or sugar molecule, other food component, or by a contaminant found in the food (e.g. food colouring, preservative etc.). If the immune system IS involved, it is usually a different class of antibody that is produced, which is why standard food allergy tests can produce negative results, yet noticeable food-related symptoms persist. Many symptoms related to food intolerance are caused by a local inflammatory response in the gut, and a sign of underlying "inflammation".
With food "intolerance", it is worth understanding, that it's rarely the food that is the problem - it is the person's response to it!
Foods containing wheat or milk for example are getting reputations as "bad foods" due to the reactions they can produce in some people. While they can very well be "problem foods" for some, they can also be very healthy foods for others. Food intolerance could be re-named as "poor digestion", as reactions to food are often the result of poor or compromised digestion!
So what can cause food intolerance?
Food intolerances are often caused by stress! Food-intolerant people often have low levels of secretory IgA, a class of protective antibodies found in the gut. IgA antibodies protect the body against the entry of foreign substances. Stress leads to a decrease in secretory IgA? a bit of vicious cycle really, but it certainly explains the relationship between stress and food intolerance!
Underlying digestive problems (e.g. low stomach acidity, gut bacterial overgrowth, a "leaky" or damaged gut lining, yeast infection or poor digestive enzyme production) are common "causes" of food intolerance and must be addressed before avoiding foods unnecessarily.
Gallbladder disease, gallstones, and pancreatitis may also be underlying causes of reactions to foods, but these will produce other symptoms too.
It is usually large food particles that cause allergic reactions, so proper breakdown of food (especially protein) via cooking and chewing is vitally important. Digestive enzymes or probiotics can often help too to ensure complete digestion, and once digestion is corrected, things can improve quite dramatically.
Signs and symptoms of food intolerance can be quite diverse, depending on how long the person has been ingesting food allergens and how the body has "adapted". Common symptoms include bloating, stomach cramping, diarrhoea or constipation - yes commonly known as "IBS"!
Long term food intolerance may produce symptoms totally unrelated to the digestive system and may include fatigue, joint and muscle aching, depression, headaches and migraine, hyperactivity in children, and even certain autoimmune disorders.
Diagnosing a food intolerance rather than an allergy (via IgE antibody blood testing) is not easy, simply because reactions to foods can occur from anywhere between 12-36 hours after eating? coupled with the fact that an individual may be reacting to more than one food!
Exclusion/reintroduction diets are the "gold standard" of tests and the most useful when done properly. They do need to be adhered to for at least 2-4 weeks initially, and are always best done under the guidance of a registered nutritionist or dietician with experience in food allergy and intolerance.
Various blood tests are now available (most useful are IgG antibody tests - available now via pin-prick blood sample) which may prove useful in many cases - but only when there are noticeable symptoms.
Vega testing (measuring energy flow) and kinesiology (muscle strength testing) are entirely reliant on the skill of the practitioner, so how effective they actually are is very difficult to measure. Whatever the test, none are 100% accurate, and changes to a person's diet based purely on the results of a test cause more confusion than clarity, and very often lead to unbalanced eating, unnecessary food phobias, and possible nutrient deficiencies.
What to do if you suspect you have a food intolerance
1) Keep a food diary and note when symptoms occur
2) Try and identify the possible problem foods
3) Seek advice on how to adapt the diet to improve digestion
4) Eat a varied, fresh and nutritious diet
The most commonly allergic foods?
Cow's milk, cheese, soya, eggs, peanuts, wheat, gluten, yeast, corn, rye, chocolate (often the milk in chocolate!), coffee, tea, alcohol (it is the chemicals and preservatives in alcohol, not the alcohol per say), citrus fruit (lemons, oranges), white potato, beef, various spices, tomato, malt, pork, chemical additives, colourings and preservatives in food (especially tartrazine, sodium benzoate, aspartame).
Food intolerances are best dealt with by avoidance of the offending food for a prescribed period of time, followed by a "rotation" diet, in which problem foods are only eaten every three to four days, instead of daily.
Young children can often re-introduce foods after three months of avoidance, whereas adults may require six to twelve months of avoidance.
Much food intolerance and even some food allergy problems settle down after long-term avoidance, and especially when digestion is improved.
When a problem food is only eaten sparingly, symptoms are less likely to return. The importance of rotating foods varies from person to person and may be related to the severity of the allergies.
The following foods are the least likely to provoke allergic reactions:
Almond milk, Quinoa milk, herb teas, apple juice and other pure or freshly squeezed fruit juices without sugar or additives (dilute 50:50 with water).
Roasted grain beverages may be used as coffee substitutes. If you like fresh coffee, Dandelion root which you can grind in a coffee grinder.
Soya milk is fine UNLESS you have an allergy to soya!
Oats (unless you have diagnosed Coeliac disease or are known to be "sensitive" to gluten)
Oatmeal and Oatbran
Puffed rice and millet cereal
Grains and flours:
Chick pea flour
Cooked whole gains:
Oats, millet, pearl or pot barley, buckwheat groats (also known as Kashi), brown rice, basmati rice, amaranth, quinoa, 100% buckwheat soba noodles, rice noodles.
Sprouted grain breads, rice bread, 100% rye or spelt bread (often fine with wheat-sensitive individuals), other wheat and yeast-free breads
100% rice cakes
100% rye crackers
Tofu (soya bean curd)
Dried beans should be soaked overnight. Pour off the water and rinse before cooking for allotted time. Canned beans often contain added sugar or other potential allergens, so if used they must be rinsed well.
Nuts and seeds
Almonds, pumpkin seeds and sunflower seeds - eat raw with no salt etc.
Nut butters are highly nutritious spreads to use in place of butter or margarine, e.g. Tahini, almond butter, hazelnut or cashew butter.
Use cold-pressed or expeller-pressed oils (available from health food stores), as they are safer. Do not use corn oil or "vegetable oil" from an unspecified source, as this is usually corn oil.
Linseed (edible linseed or flaxseed) oil
Fresh white fish, salmon, mackerel and tuna and most canned fish, lamb, poultry and fowl.
Vegetables and fruit
All vegetables except corn are generally acceptable on a low-allergen diet, as is all fruits with the exception of citrus fruits. Tomatoes can often cause problems and should be avoided by susceptible individuals. Other food members of the nightshade family (potatoes, aubergine, peppers) may prove problematic with arthritis sufferers.
Lucy-Ann Prideaux MSc BSc RNutr