Alternative biological functions of lactose: a narrative review

Lactose, commonly known as "milk sugar," offers various health benefits beyond its role as an energy source. As a precursor for essential molecules, lactose impacts calcium absorption, has low cariogenicity, affects satiety, enhances athletic performance, and potentially functions as a prebiotic for gut health. However, not all individuals can digest lactose, with a minority of the population exhibiting gastrointestinal symptoms after its consumption. The ability to digest lactose during adulthood is a genetically conferred trait known as lactase persistence, which is also likely affected by epigenetic alterations and other endogenous factors. In the present review, we highlight the multifaceted health effects of lactose, including its impact on calcium absorption, its low cariogenicity, its role in satiety control, its ability to enhance athletic performance, and its potential benefits as a prebiotic for gut health. Since these benefits are inherently dependent on lactose intake trends and the digestion capacity of populations, we also present the latest available information on the current trends in lactose consumption around the world. Overall, the gathered evidence suggests that moderate lactose consumption is recommended, as it can foster multiple lifelong health benefits.