Lactose Maldigestion, Malabsorption, and Intolerance: A Comprehensive Review with a Focus on Current Management and Future Perspectives

Abstract

Milk is a fundamental component of the diet of every mammal; nevertheless, not every individual can tolerate this kind of food, especially in adulthood. However, lactose intolerance has only been recognized in the last 50 years, and currently, lactose intolerance is defined as a clinical syndrome characterized by pain, abdominal distention, flatulence, and diarrhoea that occur after lactose consumption. Lactose is currently a common disaccharide in human nutrition, both in breastfed infants and in adults, but its digestion requires a specialized enzyme called lactase. The genetically programmed reduction in lactase activity during adulthood affects most of the world’s adult population and can cause troublesome digestive symptoms, which may also vary depending on the amount of residual lactase activity; the small bowel transit time; and, especially, the amount of ingested lactose. Several diagnostic tests are currently available for lactose intolerance, but the diagnosis remains challenging. The treatment for lactose intolerance mainly consists of reducing or eliminating the dietetic amount of lactose until the symptoms disappear, but this is hard to achieve, as lactose is present in dairy products and is even commonly used as a food additive. In addition to dietetic restriction of lactose-containing foods, lactase can be administered as an enzymatic food supplement, but its efficacy is still controversial. Recently, probiotics have been proposed for the management of lactose intolerance; certain probiotic strains have shown specific β-galactosidase activity, thus aiding in the digestion of lactose. The aim of this paper was to review the current knowledge about lactose intolerance and to discuss the potential for the use of specific probiotic strains such as dietary supplements in lactose-intolerant patients.

Clinical Utility of LCT Genotyping in Children with Suspected Functional Gastrointestinal Disorder

“…Although several diagnostic tests are available for malabsorption, diagnosis of lactose intolerance remains a challenge [ 36 ]. In this study, intolerance was defined based on the presence of symptoms during HBT.…”

“…We also evaluated dairy consumption, which is one of several interacting factors that give rise to marked interindividual differences in sensitivity to incompletely absorbed carbohydrates, and that influence the development and severity of symptoms in patients with lactose malabsorption [ 36 ]. Another aspect that can influence symptoms is the microbiota, as higher levels of Bifidobacterium species have been reported in CC versus TT or CT genotypes in European populations, a difference explained by the greater abundance of lactose available for bacterial fermentation in CC individuals due to lactose malabsorption [ 43 ].…”

The Impact of Dietary Fucosylated Oligosaccharides and Glycoproteins of Human Milk on Infant Well-Being

“…In contrast to the main milk sugar lactose, which is broken down in the small intestine by lactase into simple sugars, HMOs and the glycan part of glycoproteins are not digested and pass through the gastrointestinal tract of breastfed newborns [83,84]. In the lumen of the intestine, non-digestible milk oligosaccharides contribute to human health by shaping the newborn's microbiome and inhibit colonization by pathogenic bacteria [5,9,[84][85][86].…”

An Engineered Genetic Circuit for Lactose Intolerance Alleviation Coupled with Gut Microbiota Recovery

“…The regional prevalence is extremely high in several countries requiring an efficient therapies such as 80% in Colombia (America), 85% in China (Asia), 98% in Armenia (Europe), 100% in South Korea (Asia), Yeman (Middle East), and Ghana (Sub-Saharan Africa) [1]. Lactose intolerance (LI) symptoms, defined as the presence of gastrointestinal symptoms caused by lactose malabsorption in the small intestine, will occur when non-hydrolysed lactose flows into the colon as the bacteria substrate [1,2]. This non-hydrolysed lactose brings a high osmotic load into the colon luminal contents, which leads to increased water and electrolytes followed by softening stool, thus causing abdominal pain and cramps [3].…”

“…Enzyme replacement is another important approach for large populations of LI individuals [9]. The intake of exogenous lactase may help lactose digestion and absorption for LI subjects, but its efficacy still lacks convincing evidence [2]. Compared to short-acting enzyme replacement, probiotic supplements have an advantage in their sustainability [10] and a certain number of studies have confirmed that they can alleviate LI [11][12][13].…”