See also: lactitol - Normase - Lactulose-based laxative
Generality
Lactulose is an indigestible sugar of synthetic origin, traditionally used to solve problems of constipation; it is also used in the treatment of hepatic encephalopathy, a complication of advanced diseases affecting the liver (such as cirrhosis).
Laxative and prebiotic effects
From the chemical point of view, it is a disaccharide formed by a D-fructose molecule and a D-galactose molecule. Commercially, lactulose is often sold in the form of a yellow-orange syrup indicated for the treatment of constipation. In fact, after having escaped the digestive action of intestinal disaccharidases, lactulose behaves like a laxative with an osmotic action, filling in the intestinal lumen a sufficient amount of water to soften the feces and stimulate peristalsis. The laxative action is however delicate, so much so that lactulose is also recommended for children and the elderly (if the dietary and behavioral modifications have not yielded the desired results).
After oral administration, the lactulose reaches unchanged up to the colon, where it is catabolized by the lactobacilli with production of organic acids, such as lactic, acetic and formic acid. The prebiotic potential of this disaccharide is therefore perceived, which inhibits the development of hostile intestinal flora, such as the putrefactive one, and creates favorable environmental conditions for the growth of the symbiont (in particular lactobacilli). As a result, lactulose supplementation has a beneficial effect on the entire body.
Side effects include abdominal pain and cramps, meteorism and flatulence; excessive use can cause diarrhea, loss of water and electrolytes. Lactulose is contraindicated in the presence of galactosemia, intestinal obstruction and established hypersensitivity to this disaccharide or substances closely related to it from the chemical point of view.
Lactulose and hepatic encephalopathy
The acidification of the colic content induced by lactulose is beneficial also in the presence of hepatic encephalopathy, a neuropsychiatric syndrome due to the accumulation in the circulation of toxic substances, such as ammonia, coming from intestinal digestion and not adequately metabolized by the liver (in the healthy subject ammonia is transformed into urea in the hepatocytes and eliminated in the urine). Lactulose, by hindering the growth of ammonia-producing bacteria (such as the. E coli ) in favor of lactobacilli, and acidifying the colic content, can therefore be useful in the treatment of this disease. In particular, the reduction of colonic pH facilitates the conversion of ammonia (NH3) into the much less absorbable ammonium ion (NH4 +); if to all this we add the greater elimination of metabolites linked to the increase in peristalsis, the lactulose creates a negative gradient in the colon so that the ammonia present in the capillaries of the colic mucosa diffuses into the lumen, with a consequent reduction of the ammoniemia (concentration of the substance in plasma).
Lactulose Breath Test
The fermentation of lactulose by intestinal bacteria causes, after a certain time from its ingestion, an increase in the content of hydrogen in the expired air. This element can be exploited in different diagnostic tests (called breath tests ) to investigate, for example, the oro-cecal transit time or the possible presence of a bacterial contamination syndrome of the small intestine (the colon microorganisms rise in the terminal part of the tenuous and colonize it, interfering with the absorption of nutrients and causing abdominal swelling and alveolar disorders, in which case the lactulose breath test shows two peaks: one due to catabolism in the small intestine and one due to colic fermentation).
