Lactose and lactase--who is lactose intolerant and why?

Lactase for infantile colic: A systematic review of randomized clinical trials

Infantile colic is excessive crying for no apparent reason in an otherwise healthy infant. Although its physiopathology is not completely understood, therapies usually target gastrointestinal symptoms. This systematic review of randomized controlled trials (RCTs) analyzes the efficacy of lactase supplementation in infantile colic. PubMed, Embase, and Cochrane were searched for RCTs evaluating lactase supplementation in infants up to 6 months old with infantile colic. Out of six RCTs including 394 patients, three reported a significantly shorter crying time in the lactase group than in the placebo group, while the other three found no significant difference between groups. Of the two studies that performed the hydrogen breath test, only one reported a significant reduction in exhaled hydrogen levels. The pharmacological approach to infantile colic remains debatable, and new studies with standardized diagnostic criteria and outcomes are required to guide lactase supplementation in clinical practice.

Prebiotic Strategies to Manage Lactose Intolerance Symptoms

Lactose intolerance, which affects about 65-75% of the world's population, is caused by a genetic post-weaning deficiency of lactase, the enzyme required to digest the milk sugar lactose, called lactase non-persistence. Symptoms of lactose intolerance include abdominal pain, bloating and diarrhea. Genetic variations, namely lactase persistence, allow some individuals to metabolize lactose effectively post-weaning, a trait thought to be an evolutionary adaptation to dairy consumption. Although lactase non-persistence cannot be altered by diet, prebiotic strategies, including the consumption of galactooligosaccharides (GOSs) and possibly low levels of lactose itself, may shift the microbiome and mitigate symptoms of lactose consumption. This review discusses the etiology of lactose intolerance and the efficacy of prebiotic approaches like GOSs and low-dose lactose in symptom management.

The Dairy and Cancer Controversy: Milking the Evidence

PURPOSE OF REVIEW

Cancer risk reduction remains a significant concern for both individuals with a cancer diagnosis and those aiming to prevent it. Dairy products, a source of beneficial dietary nutrients, have sparked controversy regarding their impact on cancer risk.

RECENT FINDINGS

Evidence indicates that dairy consumption, particularly milk, can decrease colorectal cancer risk. However, cow's milk, a key dairy product, exposes individuals to growth hormones, notably insulin-like growth factor-1, potentially elevating cancer risk. Extensive research supports the link between dairy intake and heightened prostate cancer risk. Nonetheless, investigations into dairy's association with breast, ovarian, and other cancers yield mixed results. The overall data on dairy and cancer remains inconclusive. Available data suggests that a diet emphasizing fiber-rich foods such as whole grains, fruits, and vegetables, while restricting milk and dairy intake-similar to the Mediterranean dietary pattern-might mitigate cancer incidence. However, further research is crucial to elucidate the precise role of dairy products in overall cancer risk.

The roles of personalized nutrition in obesity and diabetes management: a review

Background & Aims

Nutrition is one of main environmental factor affecting obesity and its related complications such as diabetes and dyslipidemia. Due to growing prevalence of obesity across the world, it seems that nutritional advice alone is not able to combat this health problem. The present overview aimed to summarize the roles of personalized nutrition (PN) in obesity and diabetes management.

Methods

Scopus, PubMed and Google scholar were searched up to February 2021 to find relevant studies with English language in which the roles of PN in obesity and diabetes management were examined.

Results

Recent evidence revealed the importance of gene-environment interactions for management of diabetes mellitus and obesity. Moreover, microbiome research showed that personalized diet based on a combination of clinical and microbial features is likely to improve responses to therapeutic interventions. Epigenetics as well as genetic and environmental factors can also contribute to the treatment. In addition, articles showed significant roles of epigenetics and gut microbiome on providing an individualized diet for obese and diabetic patients.

Conclusion

PN compare to conventional diet can better improve metabolic status in obese and diabetic patients. Considering genetic differences and microbiome patterns along with environmental factors and their interactions are recommended for obesity and diabetes management. This approach can increase success in promoting health and preventing complications related to diabetes and obesity.

Rice straw and orange peel wastes as cheap and eco-friendly substrates: A new approach in β-galactosidase (lactase) enzyme production by the new isolate L. paracasei MK852178 to produce low-lactose yogurt for lactose-intolerant people

Converting wastes to valuable products is the main target for many kinds of research nowadays. Wastes represent an environmental problem and getting rid of it is not easy and causes pollution. Accordingly, this study offers production of the valuable enzyme β-galactosidase using rice straw and orange peel as the main medium constituents. β-galactosidase converts lactose to glucose and galactose which are simple sugars and can be fermented easily by lactose-intolerant people who represent more than 50% of the world's population. It was produced by Lactobacillus paracasei, a series isolated from fermented milk, identified using 16S ribosomal RNA gene partial sequence and had the accession number MK852178. Plackett-Burman (PB) and Central Composite (CCD) Designs optimized the production scoring 1.683(10)⁶ U/ml with a difference five times higher than the non-optimized medium. The addition of 0.3 or 0.6% of β-galactosidase serves as a good fortification for manufacturing nutritional and therapeutic low-lactose yogurt with no significant differences in total protein, total solids, fat, and ash between control and all treatments. The chemical, rheological and sensory properties of the final produced yogurt were evaluated during storage periods up to 9 days at 5 °C. In conclusion, L. paracasei MK852178 β-galactosidase is a promising additive in manufacturing low lactose yogurt for lactose-intolerant people since it reduces the lactose content and doesn't influence the chemical and sensory properties.

The Modification of the Gut Microbiota via Selected Specific Diets in Patients with Crohn's Disease

Gastrointestinal symptoms in Crohn’s disease (CD) are common and affect the quality of life of patients; consequently, a growing number of studies have been published on diet interventions in this group. The role of the gut microbiota in the pathogenesis and the progression of inflammatory bowel diseases (IBD), including CD, has been widely discussed. Mainly, a decreased abundance of Firmicutes, species of the Bifidobacterium genus, and the Faecalibacterium prausnitzii species as well as a reduced general diversity have been described. In this review article, we summarize available data on the influence of reduction diets on the microbiome of patients with CD. One of the most frequently used elimination diets in CD patients is the low-FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) diet. Although many papers show it may reduce abdominal pain, diarrhea, or bloating, it also reduces the intake of prebiotic substances, which can negatively affect the gut microbiota composition, decreasing the abundance of Bifidobacterium species and Faecalibacterium prausnitzii. Other elimination diets used by IBD patients, such as lactose-free or gluten-free diets, have also been shown to disturb the microbial diversity. On the other hand, CDED (Crohn’s disease exclusion diet) with partial enteral nutrition not only induces the remission of CD but also has a positive influence on the microbiota. The impact of diet interventions on the microbiota and, potentially, on the future course of the disease should be considered when nutritional guidelines for IBD patients are designed. Dietetic recommendations should be based not only on the regulation of the symptoms but also on the long-term development of the disease.

The role of lactose in weanling pig nutrition: a literature and meta-analysis review

Lactose plays a crucial role in the growth performance of pigs at weaning because it is a palatable and easily digestible energy source that eases the transition from milk to solid feed. However, the digestibility of lactose declines after weaning due to a reduction in endogenous lactase activity in piglets. As a result, some lactose may be fermented in the gastrointestinal tract of pigs. Fermentation of lactose by intestinal microbiota yields lactic acid and volatile fatty acids, which may positively regulate the intestinal environment and microbiome, resulting in improved gastrointestinal health of weanling pigs. We hypothesize that the prebiotic effect of lactose may play a larger role in weanling pig nutrition as the global feed industry strives to reduce antibiotic usage and pharmacological levels of zinc oxide and supra-nutritional levels of copper. Evidence presented in this review indicates that high dietary lactose improves growth performance of piglets, as well as the growth of beneficial bacteria, particularly Lactobacillus, with the positive effects being more pronounced in the first 2 weeks after weaning. However, the risk of post-weaning diarrhea may increase as pigs get older due to reduced lactase activity, high dietary lactose concentrations, and larger feed intakes, all of which may lead to excessive lactose fermentation in the intestine of the pig. Therefore, dietary lactose levels exert different effects on growth performance and gastrointestinal physiological functions in different feeding phases of weanling pigs. However, no formal recommendation of lactose for weanling pigs has been reported. A meta-analysis approach was used to determine that diets fed to swine should include 20%, 15%, and 0 lactose from d 0–7, d 7–14, and d 14–35 post-weaning, respectively. However, sustainable swine production demands that economics must also be taken into account as lactose and lactose containing ingredients are expensive. Therefore, alternatives to lactose, so called “lactose equivalents” have also been studied in an effort to decrease feed cost while maintaining piglet performance with lower dietary lactose inclusions. In summary, the present review investigated dose-response effects of dietary lactose supplementation to exert positive responses and begin to elucidate its mechanisms of action in post-weaning pig diets. The results may help to replace some or all lactose in the diet of weanling pigs, while improving production economics given the high cost of lactose and availability in some swine production markets.

Lactose and Digestible Maltodextrin in Milk Replacers Differently Affect Energy Metabolism and Substrate Oxidation: A Calorimetric Study in Piglets

BACKGROUND

In recent years, lactose-free infant formulas have been increasingly used. Digestible maltodextrins are commonly used as a substitute for lactose in these formulas, but the effects on energy metabolism are unknown.

OBJECTIVE

We aimed to evaluate the differences in energy metabolism and substrate oxidation in piglets fed milk replacers containing lactose compared with maltodextrin as the only source of carbohydrates.

METHODS

Piglets (Tempo × Topigs 20) from 8 litters were fed milk replacers containing lactose or maltodextrin (28% w/w, milk powder basis) from 1 to 9 wk of age (n =  4 litters/milk replacer). At 5 wk of age, 4 females and 4 entire males (mean ± SEM bodyweight, 10 ± 0.3 kg) were selected per litter, and housed in 16 groups of 4 littermates, with 2 females and 2 males per pen (n = 8 groups/milk replacer). Between 7 and 9 wk of age, groups were housed for 72 h in climate respiration chambers, and fed their experimental milk replacer in 2 meals per day, at 08:30 and 16:30. Heat production data were calculated from the continuous measurement of gaseous exchanges and analyzed using general linear models in SAS.

RESULTS

Resting metabolic rate was 6% less in maltodextrin- than in lactose-fed piglets, notably before the morning meal. The postprandial respiratory quotient was 13% greater in maltodextrin- than in lactose-fed piglets after both meals. Net rates of carbohydrate oxidation were on average 5% greater in maltodextrin- than in lactose-fed piglets, particularly after the afternoon meal, whereas net rates of fat oxidation were 9% less in maltodextrin- than in lactose-fed piglets, particularly after the morning meal.

CONCLUSIONS

Compared with lactose, maltodextrin in milk replacers reduced resting metabolic rate in the fasting state, and induced a shift in postprandial substrate oxidation profiles in pigs. Further research is warranted to evaluate the consequences of these metabolic changes for body composition.

Genetics of Lactose Intolerance: An Updated Review and Online Interactive World Maps of Phenotype and Genotype Frequencies

In humans the ability to digest milk lactose is conferred by a β-galactosidase enzyme called lactase-phlorizin hydrolase (LPH). While in some humans (approximately two-thirds of humankind) the levels of this enzyme decline drastically after the weaning phase (a trait known as lactase non-persistence (LNP)), some other individuals are capable of maintaining high levels of LPH lifelong (lactase persistence (LP)), thus being able to digest milk during adulthood. Both lactase phenotypes in humans present a complex genetic basis and have been widely investigated during the last decades. The distribution of lactase phenotypes and their associated single nucleotide polymorphisms (SNPs) across human populations has also been extensively studied, though not recently reviewed. All available information has always been presented in the form of static world maps or large dimension tables, so that it would benefit from the newly available visualization tools, such as interactive world maps. Taking all this into consideration, the aims of the present review were: (1) to gather and summarize all available information on LNP and LP genetic mechanisms and evolutionary adaptation theories, and (2) to create online interactive world maps, including all LP phenotype and genotype frequency data reported to date. As a result, we have created two online interactive resources, which constitute an upgrade over previously published static world maps, and allow users a personalized data exploration, while at the same time accessing complete reports by population or ethnicity.

Lactose digestion in humans: intestinal lactase appears to be constitutive whereas the colonic microbiome is adaptable

Globally, ∼70% of adults are deficient in intestinal lactase, the enzyme required for the digestion of lactose. In these individuals, the consumption of lactose-containing milk and dairy products can lead to the development of various gastrointestinal (GI) symptoms. The primary solution to lactose intolerance is withdrawing lactose from the diet either by eliminating dairy products altogether or substituting lactose-free alternatives. However, studies have shown that certain individuals erroneously attribute their GI symptoms to lactose and thus prefer to consume lactose-free products. This has raised the question whether consuming lactose-free products reduces an individual's ability to absorb dietary lactose and if lactose-absorbers should thus avoid these products. This review summarizes the current knowledge regarding the acclimatization of lactose processing in humans. Human studies that have attempted to induce intestinal lactase expression with different lactose feeding protocols have consistently shown lack of enzyme induction. Similarly, withdrawing lactose from the diet does not reduce intestinal lactase expression. Evidence from cross-sectional studies shows that milk or dairy consumption is a poor indicator of lactase status, corroborating the results of intervention studies. However, in lactase-deficient individuals, lactose feeding supports the growth of lactose-digesting bacteria in the colon, which enhances colonic lactose processing and possibly results in the reduction of intolerance symptoms. This process is referred to as colonic adaptation. In conclusion, endogenous lactase expression does not depend on the presence of dietary lactose, but in susceptible individuals, dietary lactose might improve intolerance symptoms via colonic adaptation. For these individuals, lactose withdrawal results in the loss of colonic adaptation, which might lower the threshold for intolerance symptoms if lactose is reintroduced into the diet.

Genetic and Oral Tests for the Diagnosis of Lactose Intolerance in Mixed-Ancestry Brazilians with Metabolic Syndrome

BACKGROUND/AIMS

Metabolic syndrome (MetS) comprises a cluster of physiological and anthropometric abnormalities. MetS has been linked to lactose intolerance (LI). The aim of this study was to compare the sensitivity and specificity to detect LI using 2 different tests: (1) a genetic test and (2) an oral lactose tolerance test (OLTT).

METHODS

Two hundred and fifty-four MetS patients, ≥20 years of age, of both genders, were recruited for this comparative study. Nine single nucleotide polymorphisms (SNPs) were selected for genetic investigation: rs182549and rs4988235(both considered "gold standard"); rs56064699; rs148142676; rs562211644; rs59533246; rs3754689; rs2278544,and rs10552864(as potential novel SNPs). Sensitivity and specificity, as well as positive and negative predictive values, were calculated for each genotype using WINPEPI version 11.65. Differences between positive and negative OLTT groups were considered statistically significant when p ≤ 0.05.

RESULTS

Among the selected SNPs, only rs182549(p < 0.001) and rs4988235(p < 0.001) gave similar results compared to an OLTT. The sensitivity of both SNPs to detect LI was 87 and 86%, and specificity was 83 and 82.5%, respectively.

CONCLUSION

Genetic tests using rs182549and rs4988235SNPs showed high agreement with OLTT. These genetic tests may be a good option to replace OLTT in MetS patients.

Production Optimization of an Active β-Galactosidase of Bifidobacterium animalis in Heterologous Expression Systems

β-Galactosidase (E.C.3.2.1.23) catalyzes the hydrolysis of lactose into glucose and galactose and the synthesis of galacto-oligosaccharides as well. The β-galactosidases from bacteria, especially lactobacilli, and yeast have neutral pH and are much more likely to be developed as food additives. However, the challenges of cumbersome purification, product toxicity, and low yield in protein production have limited the commercialization of many excellent candidates. In this study, we identified a β-galactosidase gene (bg42-106) in Bifidobacterium animalis ACCC05790 and expressed the gene product in Escherichia coli BL21(DE3) and Pichia pastoris GS115, respectively. The recombinant bG42-106 purified from E. coli cells was found to be optimally active at pH 6.0 and 60°C and had excellent stability over a wide pH range (5.0–8.0) and at high temperature (60°C). The specific activity of bG42-106 reached up to 2351 U/mg under optimal conditions. The galacto-oligosaccharide yield was 24.45 g/L after incubation with bG42-106 at 60°C for 2 h. When recombinant bG42-106 was expressed in Pichia pastoris GS115, it was found in the culture medium but only at a concentration of 1.73 U/ml. To increase its production, three strategies were employed, including codon optimization, disulfide formation, and fusion with a Cherry tag, with Cherry-tag fusion being most effective. The culture medium of P. pastoris that expressed Cherry-tagged bG42-106 contained 24.4 U/mL of β-galactosidase activity, which is 14-fold greater than that produced by culture of P. pastoris harboring wild-type bG42-106.

Concordance between Lactose Quick Test, hydrogen-methane breath test and genotyping for the diagnosis of lactose malabsorption in children

BACKGROUND

Lactose intolerance is a frequent condition in certain populations. Different methods for diagnosis exist. There is scarce literature regarding Lactose Quick Test (LQT) and concordance with other methods for lactose intolerance diagnosis in children.

METHODS

Prospectively, we included children who underwent gastroduodenoscopy for evaluation of abdominal pain. We obtained a duodenal sample for LQT and blood sample for genetic test to evaluate LCT C>T_-13910 variant. Later, patients underwent breath test with lactose, to evaluate malabsorption. We evaluated the concordance between the three different tests.

KEY RESULTS

We included 46 patients, 56.5% women. Mean age was 13.2 years (range 9-18 years). 66.6% of patients had lactose malabsorption according to breath test; 64.4% were homozygous CC; and 91.3% had hypolactasia (mild or severe) according to LQT. None of the patients with normolactasia had altered breath test. Genetic test had a substantial agreement (k = 0.675) with breath test and fair agreement (k = 0.301) with LQT. LQT had fair agreement (k = 0.348) with breath test.

CONCLUSIONS & INFERENCES

Genetic test had better concordance with breath test than LQT to diagnose lactose malabsorption, however, none of the patients with normal LQT had lactose malabsorption. In patients who undergo gastroduodenoscopy to study abdominal pain, it seems reasonable to perform LQT, and, in those with hypolactasia, to perform breath test.

Differences in DNA Methylation and Functional Expression in Lactase Persistent and Non-persistent Individuals

In humans the expression of lactase changes during post-natal development, leading to phenotypes known as lactase persistence and non-persistence. Polymorphisms within the lactase gene (LCT) enhancer, in particular the −13910C > T, but also others, are linked to these phenotypes. We were interested in identifying dynamic mediators of LCT regulation, beyond the genotype at −13910C > T. To this end, we investigated two levels of lactase regulation in human intestinal samples obtained from New England children and adolescents of mixed European ancestry: differential expression of transcriptional regulators of LCT, and variations in DNA methylation, and their relation to phenotype. Variations in expression of CDX2, POU2F1, GATA4, GATA6, and HNF1α did not correlate with phenotype. However, an epigenome-wide approach using the Illumina Infinium HM450 bead chip identified a differentially methylated position in the LCT promoter where methylation levels are associated with the genotype at −13910C > T, the persistence/non-persistence phenotype and lactase enzymatic activity. DNA methylation levels at this promoter site and CpGs in the LCT enhancer are associated with genotype. Indeed, taken together they have a higher power to predict lactase phenotypes than the genotype alone.

Clinical evaluation, biochemistry and genetic polymorphism analysis for the diagnosis of lactose intolerance in a population from northeastern Brazil

OBJECTIVE

This work aimed to evaluate and correlate symptoms, biochemical blood test results and single nucleotide polymorphisms for lactose intolerance diagnosis.

METHOD

A cross-sectional study was conducted in Fortaleza, Ceará, Brazil, with a total of 119 patients, 54 of whom were lactose intolerant. Clinical evaluation and biochemical blood tests were conducted after lactose ingestion and blood samples were collected for genotyping evaluation. In particular, the single nucleotide polymorphisms C>T-13910 and G>A-22018 were analyzed by restriction fragment length polymorphism/polymerase chain reaction and validated by DNA sequencing.

RESULTS

Lactose-intolerant patients presented with more symptoms of flatulence (81.4%), bloating (68.5%), borborygmus (59.3%) and diarrhea (46.3%) compared with non-lactose-intolerant patients (p<0.05). We observed a significant association between the presence of the alleles T-13910 and A-22018 and the lactose-tolerant phenotype (p<0.05). After evaluation of the biochemical blood test results for lactose, we found that the most effective cutoff for glucose levels obtained for lactose malabsorbers was <15 mg/dL, presenting an area under the receiver operating characteristic curve greater than 80.3%, with satisfactory values for sensitivity and specificity.

CONCLUSIONS

These data corroborate the association of these single nucleotide polymorphisms (C>T-13910 and G>A-22018) with lactose tolerance in this population and suggest clinical management for patients with lactose intolerance that considers single nucleotide polymorphism detection and a change in the biochemical blood test cutoff from <25 mg/dL to <15 mg/dL.

[Disorders of calcium metabolism]

The majority of clinical complaints derive from disorders of calcium metabolism and are associated with a wide variety of clinical symptoms caused by numerous diseases with entirely different types of pathophysiology. The prognosis varies from favorable to fatal depending on the pathophysiology of the underlying disorder of calcium metabolism; therefore, the diagnostic work-up aims to quickly identify the underlying disease causing the disturbance in calcium homeostasis. Every clinical situation with a diminished state of calcium absorption is treated with calcium and vitamin D in varying doses whereas every disorder with an increased calcium absorptive or resorptive state is treated with improved diuresis in addition to antiresorptive drugs, such as bisphosphonates. In many situations the management of a disturbed calcium balance requires an interdisciplinary approach in order to treat the underlying disease in parallel with correction of the calcium homeostasis.

Planning the human variome project: the Spain report

The remarkable progress in characterizing the human genome sequence, exemplified by the Human Genome Project and the HapMap Consortium, has led to the perception that knowledge and the tools (e.g., microarrays) are sufficient for many if not most biomedical research efforts. A large amount of data from diverse studies proves this perception inaccurate at best, and at worst, an impediment for further efforts to characterize the variation in the human genome. Because variation in genotype and environment are the fundamental basis to understand phenotypic variability and heritability at the population level, identifying the range of human genetic variation is crucial to the development of personalized nutrition and medicine. The Human Variome Project (HVP; http://www.humanvariomeproject.org/) was proposed initially to systematically collect mutations that cause human disease and create a cyber infrastructure to link locus specific databases (LSDB). We report here the discussions and recommendations from the 2008 HVP planning meeting held in San Feliu de Guixols, Spain, in May 2008.