Lactase is an enzyme essential in digesting lactose, or milk sugar. A disaccharide, lactose breaks down as simple sugars glucose and galactose to ease digestion, provide energy and promote physical and mental health.
About Lactase
Lactase, or lactase-phlorizin hydrolase (LPH), is an enzyme. It catalyzes the hydrolysis of lactose into its two component sugars glucose and galactose. Also known as β-galactosidase, it's produced mainly in the small intestine.
By transforming the double sugar lactose into easily absorbable forms as monosaccharides glucose and galactose, lactase enables them to enter the bloodstream. Lack of lactase causes painful / embarrassing digestive woes.
Lactase is produced by enterocytes, the absorptive cells lining the small intestine. Production happens predominantly in infancy. Genetic and environmental factors influence levels of lactase produced throughout life.
In many populations, lactase production decreases after weaning. In others, such as those with a long history of dairy consumption, lactase production persists into adulthood.
Lactase in Nature and Human Health
Purpose in Nature
In natural ecosystems, lactase enables mammals to use dairy products (ie milk) as food. In the animal kingdom, lactase activity is highest during the nursing period, ensuring youngsters can metabolize their mother’s milk.
A cup of whole milk contains approximately 150 calories and 8 grams of protein. Ability to digest lactose supports early pastoral societies, providing a consistent food source.
Human Health
The majority of people in the world are lactose intolerant, in varying degrees by ethnicity and population. About 68% of people experience some level of lactose malabsorption.
Northern Europeans are more likely to retain lactase activity into adulthood. This is due to a genetic adaptation linked to historical dairy farming practices.
How Lactose Breaks Down
Lactase functions primarily in the brush border of the small intestine. There it meets lactose from digested food. Upon recognition lactase bonds to lactose molecules and catalyzes the hydrolysis reaction.
This cleaves the glycosidic bond between the two monosaccharides glucose and galactose. The reaction can be summarized as:
Lactose + H₂O → Glucose + Galactose
Once broken down into its simpler sugars, glucose and galactose are absorbed through the intestinal walls and transported into the bloodstream, providing energy for cellular functions.
In absence of sufficient lactase, lactose remains undigested. Symptoms include bloating, abdominal pain, gas (excess burping and smelly farts) and diarrhea.
Lactase-Derived Products in Nature and Life
The products created by the action of lactase, glucose and galactose, are essential for life. Glucose is a primary energy source for cells and important for brain function.
Galactose is used in biological processes, including cell signaling and the synthesis of glycolipids and glycoproteins. Both sugars benefit the health of the gastrointestinal (GI) tract.
Probiotic bacteria use glucose and galactose as fuel to maintain healthy digestion. They're also nutrients for other organisms in the ecosystem.
Lactose-Free Products: With the increasing awareness of lactose intolerance, many dairy companies now produce lactose-free milk and yogurt. These are treated with lactase to ensure lactose is pre-digested.
Nutritional Supplements: Lactase supplements treat lactose intolerance, allowing consumption of dairy products without harmful side effects. These products help broaden dietary choices and improve nutritional intake.
Fermentation Processes: Lactase is used in the dairy fermentation industry. Enzymes produce lactose-free cheese and other fermented dairy products.
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Lactase persistence is influenced by culture. In ancient societies where dairy farming is common, those who digest lactose effectively enjoy a nutritional advantage.
Facts About Lactase
Evolutionary Response: The ability to digest lactose beyond infancy has evolved independently inhuman populations, an example of gene-culture co-evolution. The trait aligns with agricultural development.
Lifestyle Significance: In many cultures, particularly in Europe and North America, dairy products are dietary staples. Regions with high lactose intolerance such as East Asia and parts of Africa have a lower dairy consumption and alternative nutrient sources.
Lactose-Free Products: Given the prevalence of lactose intolerance affecting the majority of the global population, the dairy industry offers lactose-free alternatives. These products are treated with lactase to break down lactose before consumption.
Cultured dairy foods like yogurt and cheese are lower in lactose as most of it drains into the whey.
GI Tract & Digestive Health: Beyond helping people process dairy, lactase supports a healthy GI tract. This demonstrates the influence of nutrition on overall wellness. Digestion is also linked to mental health.
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