Lactose Intolerance

A widespread cause for digestive problems.

Extract from an article by Christiane Pies, MSc (Translated from German by Ute Marie Allison)
A case: Jane M. has been suffering from recurring digestion problems for years. Repeatedly she gets diarrhoea, sometimes accompanied by vertigo or nausea. Then she has periods when she feels fine again, but all of a sudden her problems can reoccur. Her diarrhoea attacks restrict her in her daily activities and she feels worse each year. After many years she hears about the phenomenon of milk intolerance and simply leaves out all dairy products. This improves her symptoms to a certain degree. Now she develops a profound interest in the subject and realises that lactose, the carbohydrate in milk, is not only contained in dairy but also in a lot of convenience food and even some medication. After that she also eliminates these products from her diet and her symptoms disappear completely.

Lactose and Lactase

People with lactose intolerance either cannot digest lactose (milk sugar) from food sources properly or not at all. This is caused by a lack of the enzyme lactase. Lactose is a disaccharide, which is composed of the monosaccharides galactose and glucose. Lactose represents the most important carbohydrate in the milk of mammals and the respective concentration depends on the species. Lactose is of crucial importance in nutrition and especially for babies. It is the most important energy source during the first years of a baby’s life. It makes sure that the physiological gut flora can develop and that the calcium in milk can be best utilised by the body. In the food industry lactose also plays an important role. Due to its chemical and technological properties lactose is frequently used in the production of industrial food products like baked products, sweets, meat preparations like pates, low fat foods, convenience foods, spice mixtures and artificial sweeteners. Lactose works as a binder and a carrier for aroma substances. It ensures a better firmness and a higher volume. A lot of medication also contains lactose as a filler or for taste correction. To enable absorption by the body the disaccharide has to be split into its two monosaccharides. Lactase is the necessary enzyme, which can split the ß-glycosidic bond between galactose and glucose. A lack of lactase is the world’s most frequent ‘enzyme deficiency’. About two thirds of the world’s human population loose the ability to split lactose after weaning – as do most mammals. Interestingly there is a characteristic North-South gradient. In Scandinavia only 3-8% of the population show a loss of lactase after weaning. In Germany about 13-14% and in Austria about 20% of the population is lactose intolerant. However, this number is on the increase through the rising number of immigrants from the Mediterranean. In the Mediterranean the percentage of the population with lactose intolerance is rising to about 70%, and in Africa close to the equator about 98% of the population show lactose mal-digestion.

Symptoms of Lactose Intolerance

Diarrhoea/Diarrhoea like problems (These problems can occur as early as 15-30 minutes after the lactose containing meal, a few hours later or even in the morning of the following day.)
mushy stool tummy rumbling
bloating vomiting
constipation wind
feeling sick after food tummy ache
belching colic like pain
Non-specific complaints
chronic tiredness joint pain
depressive moods restlessness
subjective feeling ill nausea
headache exhaustion
nervousness feeling low
feeling tense sleep problems
skin impurities lack of concentration
deficiency symptoms fatigue
(from Schleip, Laktoseintoleranz, Trias-Verlag)


In former times lactose intolerance was diagnosed by a lactose tolerance test. Before and after a provocation meal of 50g lactose (in children 2 g/kg, maximum of 50g) blood was taken to measure blood glucose. If there was an increase of blood glucose of over 20 mg/dl in two hours, it was assumed that sufficient lactose had been split and absorbed. Today this lactose intolerance test has been widely replaced by the H2 breath test in which the hydrogen concentration is measured before and after a provocation meal with 25g lactose (in children 1g/kg, maximum 25g). If there is an increase in H2 concentration by more than 20 ppm above the basal reading, it can be assumed that enough lactose has been metabolised. Both methods can lead to severe symptoms in lactose intolerant patients.
A gene test is a new detection method.
Only recently the genetic cause for the lactose intolerance was discovered. At the location 13910 before the lactase gene (LCT) there is a polymorphism, which determines the quantity of lactase produced. By testing the LCT genotype the genetic disposition can be determined. Our gene test is performed from a simple swab of the mouth mucosa inside the cheek. Epithelial cells stick to the cotton bud. The investigation is done on their cell nuclei.

Christiane Pies, MSc
Head of Science
Dr. Hauss Laboratory
Kieler Str. 71
24340 Eckernförde