Lactose intolerance

Symptoms of lactose intolerance

Symptoms of lactose intolerance usually happen within a few hours of having food or drink that contains lactose. They may include:

• flatulence (wind)
• diarrhoea
• bloated stomach
• stomach cramps and pains
• stomach rumbling
• feeling sick

How severe your symptoms are and when they appear depends on the amount of lactose you've consumed.

Some people may still be able to drink a small glass of milk without triggering any symptoms. Others may not even be able to have milk in their tea or coffee.

When to see your GP

The symptoms of lactose intolerance can be similar to several other conditions. It’s important to see your GP for a diagnosis before removing milk and dairy products from your diet.

For example, the symptoms above can also be caused by:

• irritable bowel syndrome (IBS) – a long-term disorder that affects the digestive system
• milk protein intolerance – an adverse reaction to the protein in milk from cows (not the same as a milk allergy)

If your GP thinks you have lactose intolerance, they may suggest avoiding foods and drinks containing lactose for two weeks. This is to see if your symptoms improve.

Causes of lactose intolerance

The body digests lactose using a substance called lactase. This breaks down lactose into two sugars called glucose and galactose. These can be easily absorbed into the bloodstream.

People with lactose intolerance don't produce enough lactase.

Most cases that develop in adults are inherited and tend to be lifelong. Cases in young children are often caused by an infection in the digestive system and may only last for a few weeks.

People commonly affected

Lactose intolerance is more common in people of Asian or African-Caribbean descent.

Lactose intolerance can develop at any age. Many cases first develop in people aged 20 to 40, although babies and young children can also be affected.

Treating lactose intolerance

There's no cure for lactose intolerance. Limiting your intake of food and drink containing lactose usually helps to control the symptoms.

Depending on what dairy products you're able to eat, you may also require additional calcium and vitamin D supplements to keep your bones strong and healthy.

In some cases, your GP may refer you for further advice and treatment.

Complications of lactose intolerance

Milk and other dairy products contain calcium, protein and vitamins such as A, B12 and D. Lactose also helps your body absorb a number of other minerals, such as magnesium and zinc.

If you're lactose intolerant, getting the right amount of important vitamins and minerals can prove difficult. This may lead to unhealthy weight loss and put you at increased risk of developing the following conditions:

• osteopenia – where you have a very low bone-mineral density- if osteopenia is not treated, it can develop into osteoporosis
• osteoporosis – where your bones become thin and weak - if you have osteoporosis, your risk of getting fractures and broken bones is increased
• malnutrition – when the food you eat doesn't give you the nutrients essential for a healthy functioning body- if you're malnourished, wounds can take longer to heal and you may start to feel tired or depressed

If you're concerned that dietary restrictions are putting you at risk of complications, you may find it helpful to speak with a dietitian for reliable information. They can advise you on your diet and whether you require food supplements.

Your GP should be able to refer you to a dietitian free of charge. Alternatively, you can contact a dietician offering services. The British Dietetic Association has information on how to find a qualified dietitian.

More useful links

• How to use your health services
• Problems with eating and food allergies in children