Lactulose

Lactulose, also known as lactulose or isomerized lactose, is systematically named 4-O-β-D-galactopyranosyl-D-fructose. It is a synthetic disaccharide formed by the combination of D-galactose and D-fructose through a β-1,4-glycosidic bond. Its molecular formula is C₁₂H₂₂O₁₁, its molecular weight is approximately 342.3, and its melting point is approximately 169℃. The finished product exists in two forms: a pale yellow, transparent, viscous syrup in liquid form, and a white powder in crystalline form. It exhibits good water and alcohol solubility, and its stability under acidic and heated conditions is superior to that of lactose, with a higher sweetness.

Preparation Process and Technical Characteristics
Lactulose is an indigestible lactose isomerization product. Currently, the preparation routes in industrial production and research mainly fall into three categories:

• Chemical isomerization method: High conversion rate, mature process, and simple operation; it is currently the only mainstream technical route for large-scale industrial production.
• Electro-activated synthesis technology: Safe, clean, and environmentally friendly, with few byproducts, but the overall conversion rate is relatively low, and industrial application has not yet been achieved.
• Enzymatic synthesis: Mild reaction conditions, high selectivity, and environmentally friendly, it is considered a green route to replace chemical methods, but technical bottlenecks such as enzyme sources, cost, and stability still exist, preventing large-scale application.

Main Application Areas

Lactulose is widely used in pharmaceuticals, food, and health products due to its well-defined physiological functions and high safety. In the pharmaceutical field, lactulose is a commonly used clinical drug, mainly used for the prevention and treatment of chronic constipation, and can also be used as an adjunct treatment for portal vein encephalopathy and related intestinal and liver diseases. In the food field, lactulose, as a prebiotic functional additive, is often used in infant formula, health foods, and dietary supplements; it has advantages such as low calories, high stability, and non-participation in Maillard reactions, and can partially replace sucrose and traditional sweeteners, enhancing the health attributes of products.

Treatment of Constipation

Used clinically as a laxative since 1960, suitable for all ages, it takes effect 24–48 hours after administration. Because the small intestine lacks the corresponding hydrolytic enzyme, lactulose is not absorbed and reaches the colon where it is broken down by intestinal bacteria, stimulating intestinal peristalsis, softening and propelling stool out.

Osmotic Regulation for Laxative Effects

Lactulose is broken down into short-chain fatty acids in the colon, acidifying the intestines, increasing osmotic pressure, and increasing stool volume, accelerating fecal transport, and helping to establish regular bowel movements. It is a mild osmotic laxative.

Inhibition of Salmonella

Studies show that lactulose can promote the excretion of non-typhoid Salmonella, with higher excretion rates and shorter excretion cycles in users, which is more effective than antibiotics in shortening the carrier state.

Improves Inflammatory Bowel Disease

By lowering intestinal pH, promoting the proliferation of beneficial bacteria such as lactobacilli, inhibiting the growth of pathogenic bacteria, reducing endotoxin production and absorption, regulating gut microbiota structure, and lowering the risk of enteritis recurrence, it can help improve inflammatory states such as ulcerative colitis and Crohn's disease.

Promotes Mineral Absorption

It can significantly improve the body's absorption rate of minerals such as calcium and magnesium, and the absorption effect increases with increasing lactulose concentration.

Regulates Bile Acid Metabolism

By regulating intestinal pH and promoting the growth of bifidobacteria, it reduces the concentration of bile acids in feces, reducing the adverse effects of excessive bile acids on the intestines and liver.

Lowers Blood Ammonia Levels

After lactulose is broken down in the colon, it lowers intestinal pH, inhibits ammonia production, and promotes the conversion of ammonia into poorly absorbed ammonium ions for excretion, thereby reducing blood ammonia accumulation and protecting the liver and nervous system.