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Background: Lactase persistence is an autosomal dominant trait commonly distributed in Europe as well as some parts of east Africa and the Arabian Peninsula. Using real-time PCR to detect the -13910C > T variant common in the European population is a reliable analysis although other variants in the probe-binding site may cause errors in analysis. The aim of this study was to determine the prevalence of the variants in a Danish cohort examined for lactose intolerance as well as to improve the real-time PCR analysis for detection of the different variants., Methods: We genotyped 3395 routine samples using real-time PCR for the -13910C > T-variant. All consecutive samples identified as -13910CC were sequenced using Sanger Sequencing. Using the SDS software we examined various quality value settings to improve on the genetic analysis., Results: Using real-time PCR resulted in 100% successful genotyping of the -13910C > T variant. By using a quality value of 99% and sequencing the undetermined samples we improved the ability of the assay to identify variants other than -13910C > T. This resulted in a reduction of the diagnostic error rate by a factor of 2.4 while increasing the expenses only 3%., Conclusions: We conclude that using a quality value of 99% in the SDS software significantly improves the diagnostic efficiency of the real-time PCR assay for detecting variants associated to lactase persistence.

Background: Lactase activity declines with age in rats, but it is not clear whether this model is also shared by humans. Few studies have evaluated lactose intolerance and malabsorption in the elderly and no definite conclusions can be drawn. The aim of our study was therefore to verify the impact of age on lactose intolerance and malabsorption., Methods: Eighty-four healthy subjects took part in the study. Thirty-three were <65 years, 17 were between 65 and 74 years and 34 were >74 years. All the subjects underwent a preliminary evaluation of intestinal gas production capacity and oro-cecal transit time by H2/CH4 breath test after lactulose. After a 3-day period, an H2/CH4 breath test after lactose was performed. The occurrence of intolerance symptoms during the test and in the 24 h after the test was recorded., Results: Breath H2 and CH4 excretion parameters at fasting and after lactulose did not differ between the three groups. Cumulative breath H2 excretion after lactose was higher in subjects >74 years than in subjects <65 years and in subjects aged 65-74 years, while no difference was found between the latter two groups. In subjects >74 years, the prevalence of lactose malabsorption was higher than in the other two groups, while no significant difference was observed between subjects <65 years and subjects aged 65-74 years. Within the malabsorber subjects, the prevalence of lactose intolerance was higher in subjects <65 years than in those aged 65-74 years and in those aged >74 years. No significant difference was found between the latter two groups. No difference was found between the three groups in terms of daily calcium intake and a significant negative correlation between symptom score and daily calcium intake was only found in the group of subjects aged <65 years., Conclusions: As age increases, the prevalence of lactose malabsorption shows an increase while the prevalence of intolerance symptoms among malabsorbers shows a decrease. Accordingly, daily calcium intake was similar among the adults and elderly studied.

Selective adult-type hypolactasia, the main cause of primary malabsorption of lactose, shows considerable variation in terms of its symptoms, which mainly depend on the amount of milk consumption. The article discusses congenital lactase deficiency and familial lactose intolerance. Links between hypolactasia and non-specific abdominal complaints, coronary heart disease and cataract are presented. The decrease in lactase activity in the brush border of jejunal mucosa, associated with diseases of the mucosa or any other condition which damages the enterocytes, is discussed as a cause of secondary hypolactasia. It is shown that adult-type primary hypolactasia and selective lactose malabsorption represent a major problem in the everyday work of general practitioners, particularly in populations where hypolactasia is common. Therefore, the examination and treatment of non-selected patients with vague abdominal complaints is important in primary health care. As the need for calcium in humans is largely met by the intake of milk, the consumption of milk has to be in amounts that are tolerable for the individual.

The principal carbohydrate of human milk is the disaccharide lactose. In human and all mammalian species, lactose is hydrolyzed in the small intestine by lactase-phlorizin hydrolase, also abbreviated as lactase. The absence of lactase results in the passage of undigested lactose into the large intestine and is associated with a well-known clinical syndrome: lactose intolerance. Low lactase levels result either from intestinal injury or, as in the majority of world's adult population, from alterations in the genetic expression of lactase. In this review terminology, pathophysiology, symptoms, diagnostic procedures, and therapy of lactose intolerance will be discussed.

Although claims for health and nutritional benefits have been made for lactic acid bacteria in fermented dairy products for nearly a century, the nutritional and therapeutic value of these organisms is still controversial. This article will review the scientific basis of these claims. There are numerous studies showing fermentation of food with lactobacilli increase the quantity, availability, digestibility, and assimilability of nutrients. The basis for this conclusion comes from direct measurements of vitamin synthesis and from increased feed efficiency when fermented products are fed to animals. There have been a number of studies showing that various fermented dairy products lower serum cholesterol levels in humans and animals. These studies are reviewed and the validity of these findings are assessed. A summary of the evidence indicating that lactase deficient individuals can eat yogurt and the mechanisms involved in this toleration is reviewed. The role of fermented dairy products in inhibiting tumor growth and chemically induced tumors in animals is discussed and the possible mechanisms involved in this protective effect are reviewed. Fermented dairy products and lypholized lactobacilli preparations have been shown to be useful in treating and preventing various intestinal infections including; salmonellosis, shigellosis and antibiotic induced diarrhea. In this context a specific lactobacillus designated GG has been shown to be useful in treating recurring diarrhea caused by a toxin produced by Clostridium difficile.