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The lowdown on: lactose intolerance

The lowdown on: lactose intolerance

by FoodMaestro | 10 February 2016

Hannah Hunter (Specialist Allergy Dietitian, Guys Hospital) provides the lowdown on ‘lactose intolerance’.

Milk allergy and lactose intolerance are very often confused with one another. Despite both involving reactions to dairy products these are however very different conditions. In a previous post we discussed milk allergy, which involves the proteins in milk and is led by the immune system. Lactose intolerance on the other hand is related to the sugars in milk.

What is lactose intolerance?

Some people are unable to digest lactose, which is the main sugar in milk. An enzyme called lactase is required to breakdown lactose into simpler sugars otherwise it passes through the bowel undigested. This is known as lactose malabsorption. Undigested lactose draws more water into the intestines and then ferments, causing symptoms such as diarrhoea, wind, abdominal cramping, bloating and nausea. Symptoms can start within 15 minutes to two hours and may last up to three days. The body may stop producing lactase (known as lactase deficiency) for a number of reasons, including genetics (it is much more common in Asian and African people) and gut infections (in which the effect may reverse). One method sometimes used to diagnose lactose intolerance is hydrogen breath testing. However this is not always a reliable test and the only way to be sure is to undertake a period of lactose avoidance followed by reintroduction.

What should be avoided?

The main sources of lactose are milk, yoghurt and soft cheeses such as cottage cheese. As well as products made from cow’s milk, this includes those derived from other animals such as goat and sheep.  The good news is that the process of making certain products derived from milk such as hard cheese, butter and creams lowers the lactose content to a level tolerated by most people with lactose intolerance. Additionally small amounts such as a splash of milk in tea or a couple of tablespoons of yoghurt with a meal are typically well tolerated. Lactose free versions of many dairy free products such as milk, yoghurt, and ice cream are becoming more widely available and are a useful addition to the diet when avoiding lactose particularly as dairy products are a good source of important nutrients such as calcium.

Lactase enzymes are available as dietary supplements and can be taken alongside foods containing lactose to improve its breakdown. Some people find these helpful, although it can be difficult to get the dosage right and for most avoidance is a better strategy. Under European labelling laws, milk ingredients must be clearly shown on food packets, usually highlighted in bold or underlined. However this labelling is designed to highlight products containing milk protein rather than lactose so it is not always easy to identify which products which may be tolerated based on the ingredients list alone. This is where FoodMaestro can come in useful. Set up your personal food profile to avoid foods containing lactose: 

Where can I get more information?

If you suspect lactose intolerance, then speak to your GP about being referred to a Dietitian who can help with both diagnosis and ensuring your diet is nutritionally adequate.

Other useful websites:

Also see:

The lowdown on: Milk Allergy

The lowdown on: Egg Allergy 

The lowdown on: Soya Allergy