The most commonly used test to detect lactose intolerance is the “hydrogen breath test”, which consists of taking a sample of our breath to measure the hydrogen produced by bacteria that metabolise the lactose we are unable to digest after drinking a lactose solution or milk. It’s a simple, non-invasive test.
Not all foods have the same level of lactose. Fermented dairy products, such as yoghurt, have less lactose, since the bacteria use it as a source of energy, reducing the amount available. Yoghurt also contains live lactic acid bacteria that can keep breaking down lactose during its passage through the intestine.
There are also some foods that—somewhat surprisingly—may contain lactose as a result of milk or dairy products used in their manufacture. People with a high level of intolerance should check the labels of all products and avoid foods that also contain lactose, whey, milk solids, etc. These ingredients are often found in processed meats, breakfast cereals, dried fruit and, in general, in processed and precooked foods. Lactose is also used as an excipient in some medicines, meaning you should check their composition carefully.
Do you suffer from flatulence, swelling, stomach cramps or diarrhoea after eating certain foods? If so, you could be lactose intolerant. It’s one of the most common food intolerances and affects 80–90 percent of the adult population in Asia and around 15 percent in Europe. It should not be confused with an allergy to cow’s milk protein intolerance, which is an immunological reaction.
Lactose is the sugar in milk and is digested by the lactase enzyme in our bodies. When the enzyme isn’t working or is present in small quantities (a condition referred to as Hypolactasia), we are unable to digest lactose. This results in poor absorption, with the associated gastrointestinal symptoms, as this molecule is highly osmotically active. When lactose is digested by the bacteria in our intestinal microbiota, instead of by us, short-chain fatty acids and large quantities of hydrogen (H2).
However, not everyone has the same level of intolerance. While genetics plays a part, there are also external factors that can cause the lack of activity. The presence of certain bacteria in our intestinal microbiota (Lactobacillus, Streptococcus, etc.) also affects our level of tolerance.
The most commonly used test to detect lactose intolerance is the “hydrogen breath test”, which consists of taking a sample of our breath to measure the hydrogen produced by bacteria that metabolise the lactose we are unable to digest after drinking a lactose solution or milk. It’s a simple, non-invasive test.
Not all foods have the same level of lactose. Fermented dairy products, such as yoghurt, have less lactose, since the bacteria use it as a source of energy, reducing the amount available. Yoghurt also contains live lactic acid bacteria that can keep breaking down lactose during its passage through the intestine.
There are also some foods that—somewhat surprisingly—may contain lactose as a result of milk or dairy products used in their manufacture. People with a high level of intolerance should check the labels of all products and avoid foods that also contain lactose, whey, milk solids, etc. These ingredients are often found in processed meats, breakfast cereals, dried fruit and, in general, in processed and precooked foods. Lactose is also used as an excipient in some medicines, meaning you should check their composition carefully.
The table below classifies common foods by low, medium and high levels of lactose:
