Lactose malabsorption related to bone fractures in old age?

Finnish researchers have discovered an interesting link between lactose malabsorption and the occurrence of bone fracture in elderly people.

It was three years ago that the Finnish researchers first identified a change affecting a single alkali in the human genome related to primary lactose malabsorption. The change is the conversion of cytosine to thymidine (genotype C/T) and it makes a person tolerate lactose for the rest of his/her life. Without this genetic change (genotype C/C), the activity of the lactase enzyme in small intestine mucosa is reduced at the age of 5 to 12 years on average, causing a deterioration of lactose tolerance.

Published in January and conducted by researchers from the Universities of Helsinki and Kuopio and the National Public Health Institute, the study investigated the relation between the genotype associated with lactose malabsorption and the occurrence of bone fracture in the elderly. The study included 483 elderly people in the City of Vantaa – 377 women and 106 men – all over 85 years of age.

The results proved that those with the genotype associated with lactose malabsorption (C/C) had substantially more hip and wrist fractures than those with the genotypes that produce life-long lactose tolerance (C/T or T/T).

The connection between C/C genotype and fractures was also detected in people who had never had symptoms of lactose intolerance despite having consumed dairy products all their lives. “It seems that even if people with this genotype consume dairy products, their bodies really cannot benefit from them,” says study author Irma Järvelä from the University of Helsinki.

The result was a surprise to the researchers because it was at odds with the results of a corresponding study completed last year on young men, according to which the genetic change associated with lactose tolerance had no connection with the bone density of the young men or their stress fractures.

Järvelä thinks that effect of the genetic change advances slowly and can only be seen in old age. However, more research will be needed to confirm this, she says.