What is lactose?
Lactose is a sugar found in the milk of mammals and derived foods such as yoghurt, creams and ice-creams.
Some prepared dishes and foods can also contain lactose. It is composed of two combined sugars, glucose and galactose. For it to be absorbed by the small intestine it is essential that these two molecules are separated.
Furthermore, lactase is an enzyme produced in the small intestine that separates lactose into two basic components (glucose and galactose) for its digestion by the intestine.
What is lactose intolerance?
When there is not sufficient lactase enzyme in the intestine, the lactose that is not decomposed into its basic components passes into the large intestine, where intestinal bacteria ferments it producing abdominal bloating, stomach upsets (sporadic pain and abdominal tension), meteorism (gas or flatulence), and nausea. With patients with high intolerance or with the ingestion of a large quantity of lactose, it is associated with diarrhoea.
When can intolerance to lactose appear?
It can appear in premature babies with an immaturity of the digestive tube, and even in children under 3 years of age. It can also be produced in a transitionary way by digestive infections or alterations of the intestinal flora from the ingestion of anti-biotics, and illnesses that harm the small intestine such as Crohn’s disease or celiac disease.
In adults it is quite common and develops to varying degrees in a permanent way. It is more frequent in Asian, African, and indigenous American adults. In the north of Europe it is less frequent due to the introduction of milk in the diet 11,000 years ago, when mankind started farming and milking animals.
Diagnosis of lactose intolerance
Lactose intolerance can be diagnosed clinically, by withdrawing the intake of milk and lactic derivatives for two weeks, and observing if symptoms improve. There are also two other methods, although they do not always confirm the diagnosis: the hydrogen breath test and the blood test for lactose intolerance.
The most used test is the hydrogen breath test, which measures the quantity of hydrogen in the exhaled air the patient breathes into a balloon. There is normally very little nitrogen in our breath. Subsequently the patient will ingest a liquid that contains lactose and tests will be carried out to examine the hydrogen exhaled. If the intestine cannot decompose the lactose, the levels of hydrogen in the breath will increase.
It is considered positive when an increase in hydrogen content is 12 parts per million over the initial level observed.
The blood test for lactose intolerance observes the increase in glucose after the ingestion of lactose. If it increases more than 30 mg/dl (1.6mmol/l) within the following 2 hours from the intake of lactose, it is considered normal (the lactose has been separated from the lactase in glucose and galactose, and therefore, glucose increases in the blood).
Increments below 20 mg/dl indicate intolerance to lactose. Intermediate increments between 20-30 mg/dl are not conclusive.
Foods that contain lactose
The reduction of lactic products that contain lactose alleviates the symptoms, but it is not recommendable to eliminate the consumption of dairy products from a nutritional point of view, being foodstuffs that contain more calcium. 1,000-1,200 mg of calcium is required to maintain adult bone health. It is necessary to eliminate the dairy products that produce uncomfortable symptoms and look for those that are tolerated for consumption within alimentation.
It is recommended to read the labels of pre-cooked and prepared foods because they may contain lactose, dried milk, milk serum or cream.
Some yoghurts, above all skimmed, contain added dried milk to improve texture and contain more lactose.
In the following section lactose values per 100 gr are shown:
| Food | Lactose content, Grams per 100 grs. |
|---|---|
| Dried skimmed milk | 53 |
| Condensed milk | 12,3 |
| Yoghurt containing dried milk | 4,7 – 5 |
| Sheep’s milk | 5,1 |
| Goat’s milk | 4,5 |
| Cow’s milk | 5 – 4,3 |
| Yoghurt | 2,7 |
| Fresh cheese | 2,7 |
| Cream | 2,4 |
| Cured cheeses | < 1 or traces |
| Butter | 0-0,5 |
Products that contain less lactose
Butter from cow’s milk, ice-cream and cured or hard cheeses, some yoghurts that do not contain dried milk, milk and lactose-free products, cow’s milk treated with lactase for older children and adults, soya formula for babies less than 2 years, soy milk or rice milk for small children.
What can a person do if they consume products with lactose even if it does not agree with them?
Lactase enzymes can be added to normal milk or can be taken in capsules, which are sold in pharmacies. A strong lactase tablet corresponds to tolerating the consumption of a glass of milk with lactose.
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