Lactose intolerance: the medical point of view
Some subjects experience intolerance signs (borborygmi, flatus, abdominal
distension, pain, and in the worse cases diarrhoea) when ingesting lactose.
These lactose intolerant subjects represent a part of the subjects who are not
able to fully digest significant loads of lactose (i.e. lactose malabsorbers). Many
physiological and physio-pathological studies have provided the explanations
for these two situations. Lactose i.e. the main milk sugar cannot be absorbed as
such in the intestine but first needs to be digested in the small bowel by a lactase.
The non absorbed lactose exerts an osmotic effect which induces secretion
of water and sodium into the intestinal lumen. This increases the volume of
the chime and accelerates the transit of small bowel contents. The part of lactose
reaching the colon is fermented by the colonic bacteria. Some of the lactose
intolerant subjects are not able to diagnose lactose intolerance by
themselves and consult doctors, however the majority avoid spontaneously milk
products. Other individuals think that they do not tolerate milk products
although blinded studies fail to confirm it, however the consequence is the
same i.e. they avoid consuming milk products, and sometimes consult doctors.
As milk products constitute the main source of calcium in food, subjects avoiding
them are exposed to osteopenia (CARROCCIO et al., 1998; HONKANEN et al.,
1996; DI STEFANO et al., 2002). We review here the main factors influencing lactose
intolerance; the frequency of lactose intolerance to various lactose loads;
and the possibility to treat lactose intolerance without avoiding all milk products.
Philippe MARTEAU, Eugenia MORALES, Tuula VESA, Riitta KORPELA