Lactase persistence may have an independent origin in Tibetan populations from Tibet, China. J Hum Genet. 2012;57:394-397. [PMID: 22572735 DOI: 10.1038/jhg.2012.41]

Genetic aspects of lactase deficiency in indigenous populations of Siberia

The ability to metabolize lactose in adulthood is associated with the persistence of lactase enzyme activity. In European populations, lactase persistence is determined mainly by the presence of the rs4988235-T variant in the MCM6 gene, which increases the expression of the LCT gene, encoding lactase. The highest rates of lactase persistence are characteristic of Europeans, and the lowest rates are found in East Asian populations. Analysis of published data on the distribution of the hypolactasia-associated variant rs4988235-C in the populations of Central Asia and Siberia showed that the frequency of this variant increases in the northeastern direction. The frequency of this allele is 87 % in Central Asia, 90.6 % in Southern Siberia, and 92.9 % in Northeastern Siberia. Consequently, the ability of the population to metabolize lactose decreases in the same geographical direction. The analysis of paleogenomic data has shown that the higher frequency of the rs4988235-T allele in populations of Central Asia and Southern Siberia is associated with the eastward spread of ancient populations of the Eastern European steppes, starting from the Bronze Age. The results of polymorphism analysis of exons and adjacent introns of the MCM6 and LCT genes in indigenous populations of Siberia indicate the possibility that polymorphic variants may potentially be related to lactose metabolism exist in East Asian populations. In East Asian populations, including Siberian ethnic groups, a ~26.5 thousand nucleotide pairs long region of the MCM6 gene, including a combination of the rs4988285-A, rs2070069-G, rs3087353-T, and rs2070068-A alleles, was found. The rs4988285 and rs2070069 loci are located in the enhancer region that regulates the activity of the LCT gene. Analysis of paleogenomic sequences showed that the genomes of Denisovans and Neanderthals are characterized by the above combination of alleles of the MCM6 gene. Thus, the haplotype discovered appears to be archaic. It could have been inherited from a common ancestor of modern humans, Neanderthals, and Denisovans, or it could have been acquired by hybridization with Denisovans or Neanderthals. The data obtained indicate a possible functional significance of archaic variants of the MCM6 gene.

Advances in Low-Lactose/Lactose-Free Dairy Products and Their Production

With increasing health awareness worldwide, lactose intolerance has become a major concern of consumers, creating new market opportunities for low-lactose/lactose-free dairy foods. In recent years, through innovating processes and technologies, dairy manufacturers have significantly improved the variety, and functional and sensory qualities of low-lactose and lactose-free dairy products. Based on this, this paper first covers the pathology and epidemiology of lactose intolerance and market trends. Then, we focus on current advantages and disadvantages of different lactose hydrolysis technologies and improvements in these technologies to enhance nutritional value, and functional, sensory, and quality properties of lactose-free dairy products. We found that more and more cutting-edge technologies are being applied to the production of lactose-free dairy products, and that these technologies greatly improve the quality and production efficiency of lactose-free dairy products. Hopefully, our review can provide a theoretical basis for the marketing expansion and consumption guidance for low-lactose/lactose-free dairy products.

Microbiota-gut-brain axis and related therapeutics in Alzheimer's disease: prospects for multitherapy and inflammation control

Alzheimer's disease (AD) is the most common type of dementia in the elderly and causes neurodegeneration, leading to memory loss, behavioral disorder, and psychiatric impairment. One potential mechanism contributing to the pathogenesis of AD may be the imbalance in gut microbiota, local and systemic inflammation, and dysregulation of the microbiota-gut-brain axis (MGBA). Most of the AD drugs approved for clinical use today are symptomatic treatments that do not improve AD pathologic changes. As a result, researchers are exploring novel therapeutic modalities. Treatments involving the MGBA include antibiotics, probiotics, transplantation of fecal microbiota, botanical products, and others. However, single-treatment modalities are not as effective as expected, and a combination therapy is gaining momentum. The purpose of this review is to summarize recent advances in MGBA-related pathological mechanisms and treatment modalities in AD and to propose a new concept of combination therapy. "MGBA-based multitherapy" is an emerging view of treatment in which classic symptomatic treatments and MGBA-based therapeutic modalities are used in combination. Donepezil and memantine are two commonly used drugs in AD treatment. On the basis of the single/combined use of these two drugs, two/more additional drugs and treatment modalities that target the MGBA are chosen based on the characteristics of the patient's condition as an adjuvant treatment, as well as the maintenance of good lifestyle habits. "MGBA-based multitherapy" offers new insights for the treatment of cognitive impairment in AD patients and is expected to show good therapeutic results.

Revealing Joseon period People's single nucleotide polymorphism associated with lactase gene by ancient DNA analysis of human remains from archaeological sites in Korea

Lactase non-persistence (LNP), one of the causes of lactose intolerance, is related to lactase gene associated single nucleotide polymorphisms (SNPs). Since the frequency of LNP varies by ethnic group and country, the research to reveal the presence or absence of LNP for specific people has been conducted worldwide. However, in East Asia, the study of lactase gene associated SNPs have not been sufficiently examined so far using ancient human specimens from archaeological sites. In our study of Joseon period human remains (n=14), we successfully revealed genetic information of lactase gene associated SNPs (rs1679771596, rs41525747, rs4988236, rs4988235, rs41380347, rs869051967, rs145946881 and rs182549), further confirming that as for eight SNPs, the pre-modern Korean people had a lactase non-persistent genotype. Our report contributes to the establishment of LNP associated SNP analysis technique that can be useful in forthcoming studies on human bones and mummy samples from East Asian archaeological sites.

Management of Social Behaviour of Domestic Yaks in Manang, Nepal: An Etho-Ethnographic Study

Herdsmen use different techniques, as per varying geographies and cultures, to keep the cohesion within herds and avoid animals getting lost or predated. However, there is no study on the social behaviour of yaks and herdsmen management practices. Therefore, this ethology study was initiated by ethnographic inquiries. In Manang, the success of the shepherd is dictated by his personal attribute of 'Khula man' or open-heartedness. This attribute refers to good intentions and emotions such as empathy, which allow the shepherd to focus more on others than on himself. This cultural way of assessing the skills required to become a successful and knowledgeable shepherd guided us to study the effect of cultural values on the herd's social behaviour. We collected data from two herds living at the same settlement (Yak kharka, 4100 m altitude, Nepal) by equipping them with loggers. One of the herdsmen used the tether rope while the other one did not. Moreover, the Thaku herd had a more proactive shepherd than the Phurba one. In each herd, 17 animals were equipped with one Actigraph wgt3x-BT to measure activity using an accelerometer and spatial associations using a proximity recorder. One of the herds was equipped with GPS (N = 11) as well. Using GPS locations and activity, we showed that the two herds were cohesive and synchronised their activities but the Thaku herd (tether rope herd) was more cohesive than the Phurba herd based on the Actigraph signals. The shepherds also have personal knowledge of the social relationships of individual animals in their herds and use these relationships to keep the group cohesive and to manage cattle well.

Development of a novel SNP assay to detect lactase persistence associated genetic variants

BACKGROUND

In adulthood the activity of the lactase enzyme is inherited as autosomal dominant form associated to Single nucleotide polymorphisms (SNPs). The present research was aimed to develop a novel genetic method to test lactase non persistence more powerfully.

METHODS AND RESULTS

In our study, we selected eight different SNPs that are associated with lactase persistence from Caucasian, Arabian Bedouins, sub-Saharian Africans and Asian populations to set up an approach to detect all the eight different SNPs at the same time in the same sample. This technique is centred on the identification of SNPs with a single nucleotide primer extension method using Sanger sequencing and capillary electrophoresis.

CONCLUSIONS

Our method allowed us to check the genotype asset of eight SNPs related to lactase persistence simultaneously and in a very efficient manner. It could be applied to a higher number of SNPs in a single reaction.

Fermented foods and probiotics: An approach to lactose intolerance

The aim of this review was to present various topics related to lactose intolerance with special attention given to the role of fermented foods and probiotics in alleviating gastrointestinal symptoms. Lactose intolerance is a common digestive problem in which the human body is unable to digest lactose, known as milk sugar. Lactose intolerance can either be hereditary or a consequence of intestinal diseases. Recent work has demonstrated that fermented dairy products and probiotics can modify the metabolic activities of colonic microbiota and may alleviate the symptoms of lactose intolerance. We suggest that, lactose free dairy products could be recommended as alternatives for the alleviation of lactose intolerance and for the promotion of human health and wellness.

High-altitude Tibetan fermented milk ameliorated cognitive dysfunction by modified gut microbiota in Alzheimer's disease transgenic mice

Alzheimer's disease (AD) is a complex neurodegenerative disease that is regarded as a growing global challenge. Accumulating evidence linking gut microbiota with AD has become intriguing. The purpose of this study was to investigate how Tibetan fermented milk affected memory impairment in amyloid precursor protein (APP)/presenilin-1 (PS1) mice, using APP/PS1 transgenic mice as examples. We used Tibetan fermented milk (the yogurt samples with the highest microbial diversity were selected by 16S sequencing) as an intervention in such mice for 20 weeks, with aseptic maintenance feed as their basic diet. At the end of the intervention, we collected fecal samples for 16S ribosomal ribonucleic acid (rRNA) sequencing. We evaluated the effects of Tibetan fermented milk on the mice's cognitive function by behavioral examination, and deposition of amyloid beta (Aβ) in the hippocampus and cortex of the mice by immunohistochemistry (IHC). Results showed that Tibetan fermented milk could improve cognitive impairment in APP/PS1 mice, including spatial learning/memory and object recognition/memory. Sequencing of 16S ribosomal RNA in mouse feces showed that Tibetan fermented milk increased intestinal microbial diversity and elevated the relative abundance of Bacteroides and Faecalibacterium spp. Mucispirillum and Ruminiclostridium were highly abundant in APP/PS1 mice. Additionally, correlation analysis revealed that cognitive function was correlated negatively with Mucispirillum abundance and positively with Muribaculum and Erysipelatoclostridium abundance. Tibetan fermented milk could also reduce deposition of Aβ in the cerebral cortex and hippocampus. Our data suggested that long-term intake of Tibetan fermented milk had a beneficial effect on the composition of intestinal flora, which was correlated with cognitive improvements in APP/PS1 mice and seemed to help prevent and treat AD-induced cognitive decline.

Why and when was lactase persistence selected for? Insights from Central Asian herders and ancient DNA

The genetic adaptation of humans to the consumption of milk from dairying animals is one of the most emblematic cases of recent human evolution. While the phenotypic change under selection, lactase persistence (LP), is known, the evolutionary advantage conferred to persistent individuals remains obscure. One informative but underappreciated observation is that not all populations whose ancestors had access to milk genetically adapted to become lactase persistent. Indeed, Central Asian herders are mostly lactase nonpersistent, despite their significant dietary reliance on dairy products. Investigating the temporal dynamic of the -13.910:C>T Eurasian mutation associated with LP, we found that, after its emergence in Ukraine 5,960 before present (BP), the T allele spread between 4,000 BP and 3,500 BP throughout Eurasia, from Spain to Kazakhstan. The timing and geographical progression of the mutation coincides well with the migration of steppe populations across and outside of Europe. After 3,000 BP, the mutation strongly increased in frequency in Europe, but not in Asia. We propose that Central Asian herders have adapted to milk consumption culturally, by fermentation, and/or by colonic adaptation, rather than genetically. Given the possibility of a nongenetic adaptation to avoid intestinal symptoms when consuming dairy products, the puzzle then becomes this: why has LP been selected for at all?

Identification of novel genetic variants in the mutational hotspot region 14 kb upstream of the LCT gene in a Mexican population

Several polymorphic loci linked to lactase persistence (LP) have been described, all located in a small mutational hotspot region far upstream (∼14 kb) of the lactase (LCT) gene. One is typically found in Europeans, LCT -13910C > T, several others are found in East Africans and Arabs, e.g. LCT -13907C > G and LCT -13915T > G. The possibility of similar loci, specific to populations in South and Central America, has not received much attention so far. To identify possible novel polymorphisms in the mutational hotspot region, we sampled 158 subjects from a rural area in South-Central Mexico. DNA was isolated from serum, and Sanger sequencing of a 501 bp region spanning the LCT -13910C > T hotspot was successfully performed in 150 samples. The frequency of the European-type LCT -13910 T-allele was q = 0.202, and 35% of the population was thus lactase-persistent (CT or TT). Sixteen novel genetic variants were found amongst 11 of the subjects, all were heterozygotes: seven of the subjects were also carriers of at least one LCT -13910 T-allele. Thus, the mutational hotspot region is also a hotspot in the rural Mexican population: 11/150 subjects carried a total of 16 previously unknown private mutations but no novel polymorphism was found. The relationship between such novel genetic variants in Mexicans and lactase persistence is worthy of more investigation.

Coevolution between Cancer Activities and Food Structure of Human Being from Southwest China

Yunnan and Tibet are the lowest cancer mortality and the largest producer for anticancer crops (brown rice, barley, buckwheat, tea, walnut, mushrooms, and so forth). Shanghai and Jiangsu province in China have the highest mortality of cancers, which are associated with the sharp decline of barley.

Prevalence of lactose intolerance in Chile: a double-blind placebo study

BACKGROUND AND STUDY AIMS

Lactase non-persistence (LNP), or primary hypolactasia, is a genetic condition that mediates lactose malabsorption and can cause lactose intolerance. Here we report the prevalence of lactose intolerance in a double-blind placebo study.

METHODS

The LCT C>T-13910 variant was genotyped by RT-PCR in 121 volunteers and lactose malabsorption was assessed using the hydrogen breath test (HBT) after consuming 25 g of lactose. Lactose intolerance was assessed by scoring symptoms (SS) using a standardized questionnaire following challenge with a lactose solution or saccharose placebo.

RESULTS

The LNP genotype was observed in 57% of the volunteers, among whom 87% were HBT⁺. In the HBT⁺ group the median SS was 9 and in the HBT⁻ group the median SS was 3 (p < 0.001). No difference was observed in the SS when both groups were challenged with the placebo. The most common symptoms included audible bowel sounds, abdominal pain and meteorism. In the ROC curve analysis, an SS ≥ 6 demonstrated 72% sensitivity and 81% specificity for predicting a positive HBT. To estimate prevalence, lactose intolerance was defined as the presence of an SS ≥ 6 points after subtracting the placebo effect and 34% of the study population met this definition.

CONCLUSIONS

The LNP genotype was present in more than half of subjects evaluated and the observed prevalence of lactose intolerance was 34%.

Mitochondrial DNA genetic diversity and LCT-13910 and deltaF508 CFTR alleles typing in the medieval sample from Poland

We attempted to confirm the resemblance of a local medieval population and to reconstruct their contribution to the formation of the modern Polish population at the DNA level. The HVR I mtDNA sequence and two nuclear alleles, LCT-13910C/T SNP and deltaF508 CFTR, were chosen as markers since the distribution of selected nuclear alleles varies among ethnic groups. A total of 47 specimens were selected from a medieval cemetery in Cedynia (located in the western Polish lowland). Regarding the HVR I profile, the analyzed population differed from the present-day population (P = 0.045, F(st) = 0.0103), in contrast to lactase persistence (LP) based on the LCT-13910T allele, thus indicating the lack of notable frequency changes of this allele during the last millennium (P = 0.141). The sequence of the HVR I mtDNA fragment allowed to identify six major haplogroups including H, U5, T, K, and HV0 within the medieval population of Cedynia which are common in today's central Europe. An analysis of haplogroup frequency and its comparison with modern European populations shows that the studied medieval population is more closely related to Finno-Ugric populations than to the present Polish population. Identification of less common haplogroups, i.e., Z and U2, both atypical of the modern Polish population and of Asian origin, provides evidence for some kind of connections between the studied and foreign populations. Furthermore, a comparison of the available aDNA sequences from medieval Europe suggests that populations differed from one another and a number of data from other locations are required to find out more about the features of the medieval gene pool profile.

Gene-environment interactions in human health: case studies and strategies for developing new paradigms and research methodologies

THE SYNERGISTIC EFFECTS OF GENES AND THE ENVIRONMENT ON HEALTH ARE EXPLORED IN THREE CASE STUDIES: adult lactase persistence, autism spectrum disorders, and the metabolic syndrome, providing examples of the interactive complexities underlying these phenotypes. Since the phenotypes are the initial targets of evolutionary processes, understanding the specific environmental contexts of the genetic, epigenetic, and environmental changes associated with these phenotypes is essential in predicting their health implications. Robust databases must be developed on the local scale to deconstruct both the population substructure and the unique components of the environment that stimulate geographically specific changes in gene expression patterns. To produce these databases and make valid predictions, new, locally focused, and information-dense models are needed that incorporate data on evolutionary ecology, environmental complexity, local geographic patterns of gene expression, and population substructure.

Advances in research of intestinal lactase

DLactase is a type of disaccharidase which exists on the surface of small intestinal villi of mammals and can be generated by many beneficial intestinal bacteria. The majority of humans are deficient in lactase and approximately 2/3 of the world′s population are affected by lactase deficiency. Nowadays, the research of the metabolism of lactose, lactose enzyme expression and regulation has attracted wide attention both in China and other countries. In this article, we will review recent progresses in research of intestinal lactase.