The Consumer Education Project of Milk SA

Is Lactose Intolerance the same as a Milk Allergy?

Milk allergy and lactose intolerance are two very different issues related to the same food stuff. Milk allergy is generally an immune response to the protein found in milk which results in the immune system being stimulated and a reaction results such as an itch, rash, nausea, vomiting and breathing problems depending on the severity of the sensitivity and the number of times the person has been exposed. In general, an immune reaction gets more intense and more severe the more exposures. This type of reaction can be life threatening.

On the other hand, lactose intolerance is a sensitivity and reaction to the carbohydrate found in milk, known as lactose. This reaction is not in the immune system but rather within the gut. The reaction is generally brought about as a result of too little or inefficient lactase activity – lactase is then enzyme in the gut needed to digest the lactose. If someone is born with an inability to make this enzyme, they will have what is known as primary lactose intolerance. They will either need to avoid all lactose-containing foods all their lives or alternatively should they consumer lactose foods will need to supplement a digestive enzyme supplement to assist with digestion. The gut is not a smooth tube but rather a tube with a rough or convoluted wall that looks a little like fingers sticking up – these finger like projections in the middle of the gut tube are called villi and they have a number of roles to play in the gut – one of which is to increase the surface area of the gut resulting in more chance for absorption. The other is that in their tips, they house the cells responsible for the manufacture of the enzyme lactase. This is important to know as an individual can also develop what is called transient lactose intolerance as a result of reversible damage to these tips. This happens as a result of diarrhoea, causing the finger-like projections to be “flattened” and as a result the villi are not able to make lactase resulting in lactose intolerance. Once the villi are restored back however, the lactase is manufactured again and lactose intolerance is restored.


No. Lactose intolerance is merely the absence of the enzyme that digests the lactose (natural sugar in milk) and besides the discomfort and a sour smelling stool, there is no harm to the body.

Milk allergy, on the other hand, means that the body treats the protein in milk as an ‘imposter’. To fight the perceived threat of the milk protein ‘imposter’, the body calls out the ‘riot squad’ to get rid of the threat. The immune system goes on high alert and an allergic reaction develops. This can be mild in the form of itchy skin or eczema, more severe in the form of breathing difficulties, or even life threatening as in an anaphylactic shock, which is not common with milk allergies.


For further reading please visit our page on Lactose Intolerance.

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