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
specialized 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
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, diarrhea
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
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
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
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,
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
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,
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
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