Human Adult-Onset Lactase Decline: An Update

Abstract

Human adult-onset lactase decline is a biologic feature characteristic of the maturing intestine in the majority of the world's population. The digestion and absorption of lactose, the major carbohydrate in milk and also the main substrate for lactase, is often variable, a consequence of lactase levels, gastric emptying rate, and colonic salvage. Although commercially available "lactase " products alleviate symptoms in many lactoseintolerant people, a greater understanding of this variability in lactose tolerance could lead to interventions that reduce the rate of gastric emptying andlor increase the proliferation of lactose-metabolizing bacteria in the colon, leading to more efficient lactose utilization. Adult-onset lactase decline appears to be a risk factor for developing osteoporosis, owing to avoidance of dairy products or interference of undigested lactose with calcium absorption. Elderly with both adult-onset lactase decline and atrophic gastritis or those undergoing anti-ulcer treatment may have an increased risk of low calcium absorption owing to the lack of gastric acid that facilitates calcium uptake. Thus, lactose-intolerant elders should monitor their calcium nutrition status carefully.

Several Different Lactase Persistence Associated Alleles and High Diversity of the Lactase Gene in the Admixed Brazilian Population

“…Most intolerant subjects present symptoms like bloating, flatulence, nausea, and diarrhea after consumption of fresh milk [2]–[4]. Moreover, adult-onset lactase decline appears to be a risk factor for osteoporosis due to avoidance of dairy products or undigested lactose interference with calcium absorption [5].…”

Evolution of Infant and Young Child Feeding: Implications for Contemporary Public Health

“…After approximately six months of age, complementary and family foods (235) increasingly contribute to the diet (131), as chewing (210,211,217), tasting (14,47,142), and digestive (134,194) competencies develop. Frequency of suckling and volume of milk consumed do not necessarily diminish after six months in healthy babies, and the complementary feeding phase continues at least until the third year of life, during which breast milk remains an important, relatively sterile source of nutrients and immune protection.…”

Fermented Milk: Health Benefits Beyond Probiotic Effect

“…The decline of the intestinal b-galactosidase (b-gal; commonly know as lactase) activity is a biological characteristic of the maturing intestine in the majority of the world's population (Lee and Krasinski 1998). With the exception of the inhabitants of northern and central Europe and Caucasians in North America and Australia, over 70% of adults worldwide are lactose malabsorbers (de Vrese and others 2001).…”