It is important to understand that lactose intolerance and milk allergy are very different conditions.
Lactose intolerance
Lactose is a natural sugar found in milk which we use as energy, especially during the early stages of life. Lactose is broken down by enzymes so it can enter the bloodstream to be used by the body. Some people are sensitive to the milk sugar lactose and this sensitivity is called ‘lactose intolerance'.
Lactose intolerance occurs when we lack or don't have enough of the enzyme ‘lactase', which breaks down lactose before it's absorbed by the body. The unabsorbed lactose then passes through the digestive system where it's fermented by bacteria, resulting in production of fatty acids and gases which cause wind, bloating and diarrhoea.
This condition normally appears in adults, as the amount of lactase enzyme decreases with age. Lactose intolerance in more common in certain ethnicities where milk doesn't form a common part of the diet, for example in Southern Asian ethnic groups.
It can also appear secondary to other problems such as digestive disorders like coeliac disease, Crohn's disease and gastroenteritis, and after intestinal trauma such surgery. Hereditary alactasia - complete lack of the enzyme required to break down lactose from birth - is rare.
There is no medical treatment for lactose intolerance, but symptoms can be avoided by controlling the amount of lactose in the diet. Adults with lactose intolerance may be able to tolerate a small amount of milk without reacting and can often have cheese and yoghurts without a problem.
Milk from mammals including cows, goats and sheep all contain lactose. This means that goat's milk and sheep's milk aren't suitable alternatives to cows' milk for people who are intolerant to lactose. Soya, rice or oat milk may be a good substitute.
If you think you or your child may have lactose intolerance it's important to speak to your GP to get a definite diagnosis before deciding to exclude lactose from your diet because milk and dairy products provide a host of nutrients which are particularly important for children.
Milk Allergy
Individuals who have a milk allergy are allergic or intolerant to the proteins in cow's milk, not the sugar in milk. The proteins that most individuals are allergic to are called casein and whey.
Cow's milk allergy is the most common allergy in childhood affecting 2 to 7% of babies under a year old. Children usually grow out of milk allergy by the time they are three, but about one-fifth are still allergic to milk as adults.
Reactions caused by milk allergy can affect any part of the body and can include rashes, diarrhoea, vomiting, stomach cramps and difficulty breathing, which in rare cases can become anaphylaxis.
Anaphylaxis is a serious life-threatening condition where the lips and mouth become swollen and they have difficulty breathing, which could make them collapse. If this happens 999 should be dialled immediately.
Children with milk allergies shouldn't be given goat's or sheep's milk as a substitute - even though they contain different proteins to cow's milk, they are very similar and could still cause a reaction. Infants with cow's milk allergy similarly shouldn't be given sheep's or goat's milk-derived formulas, but could have a highly hydrolysed milk formula. It's important to consult a GP or dietitian before choosing a formula.
Note:
There are alternative products which can be used to avoid milk or lactose. However, don't cut milk and dairy products out of your diet, or your child's diet, before talking to your GP or a dietitian because you may suffer from a lack of important nutrients such as calcium.
It's important to remember that infants under the age of one should not drink cow, sheep or goats' milk, regardless of whether or not they suffer from intolerance or allergy, as they don't contain the necessary nutrients needed by the infant, so will be at a higher risk of deficiencies such as iron deficiency.
