Lactose intolerance and milk allergy
Lactose is a sugar found naturally in milk. It’s important to distinguish between lactose intolerance and
milk allergy, because milk allergy can cause severe reactions.
Lactose intolerance is caused by a shortage of the enzyme lactase, which is needed to break down
lactose so it can be absorbed into the bloodstream. When someone doesn’t have enough of this
enzyme, lactose isn’t absorbed properly from the gut, which can cause symptoms such as bloating and
Allergy to cows’ milk is the most common food allergy in childhood, and affects 2-7% of babies under
one year old. It’s more common in babies with atopic dermatitis. A reaction can be triggered by small
amounts of milk, either passed to the baby through the mother’s breast milk from dairy products she
has eaten, or from feeding cows’ milk to the baby.
Children usually grow out of milk allergy by the age of three, but about a fifth of children who have an
allergy to cows’ milk will still be allergic to it as adults. The symptoms of milk allergy are often mild
and can affect any part of the body. They can include rashes, diarrhoea, vomiting, stomach cramps
and difficulty in breathing. In a very few cases, milk allergy can cause anaphylaxis.
Cows’ milk allergy is caused by a reaction to a number of allergens in cows’ milk, such as casein and
whey. Casein is the curd that forms when milk sours, and whey is the watery part that is left when the
curd is removed.
People can be allergic to either whey or casein, or both, and an allergic reaction can be triggered by
very small amounts of these allergens in people who are sensitive. Heat treatment, such as
pasteurisation, changes whey, so people who are sensitive to whey might not react to pasteurised
milk. But heat treatment doesn’t affect casein, so someone who is allergic to casein will probably react
to all types of milk and milk products.
Milk from other mammals (such as goats and sheep), and hydrolysed milk and soya formulas, are
sometimes used as a substitute for babies who are at risk of developing cows’ milk allergy. However,
the allergens in milk from goats and sheep are very similar to those in cows’ milk. This means that
someone with a cows’ milk allergy might react to these other types of milk as well, so goats and sheep
milk aren’t suitable alternatives for people who are sensitive to cows’ milk.
Some highly hydrolysed milk formulas are suitable for babies with cows’ milk allergy, but other types
of formula, such as partially hydrolysed milk and soya formulas, aren’t suitable, because many babies
with cows’ milk allergy might react to them as well.
Which foods can I substitute?
Milk is rich in protein, calcium and Vitamins A and B and it is important to insure an adequate intake of
these elements w...