Evolution of infant nutrition

A molecular basis for bifidobacterial enrichment in the infant gastrointestinal tract

Bifidobacteria are commonly used as probiotics in dairy foods. Select bifidobacterial species are also early colonizers of the breast-fed infant colon; however, the mechanism for this enrichment is unclear. We previously showed that Bifidobacterium longum subsp. infantis is a prototypical bifidobacterial species that can readily utilize human milk oligosaccharides as the sole carbon source. MS-based glycoprofiling has revealed that numerous B. infantis strains preferentially consume small mass oligosaccharides, abundant in human milks. Genome sequencing revealed that B. infantis possesses a bias toward genes required to use mammalian-derived carbohydrates. Many of these genomic features encode enzymes that are active on milk oligosaccharides including a novel 40-kb region dedicated to oligosaccharide utilization. Biochemical and molecular characterization of the encoded glycosidases and transport proteins has further resolved the mechanism by which B. infantis selectively imports and catabolizes milk oligosaccharides. Expression studies indicate that many of these key functions are only induced during growth on milk oligosaccharides and not expressed during growth on other prebiotics. Analysis of numerous B. infantis isolates has confirmed that these genomic features are common among the B. infantis subspecies and likely constitute a competitive colonization strategy used by these unique bifidobacteria. By detailed characterization of the molecular mechanisms responsible, these studies provide a conceptual framework for bifidobacterial persistence and host interaction in the infant gastrointestinal tract mediated in part through consumption of human milk oligosaccharides.

Role of gut microbiota in early infant development

Early colonization of the infant gastrointestinal tract is crucial for the overall health of the infant, and establishment and maintenance of non-pathogenic intestinal microbiota may reduce several neonatal inflammatory conditions. Much effort has therefore been devoted to manipulation of the composition of the microbiota through 1) the role of early infant nutrition, particularly breast milk, and supplementation of infant formula with prebiotics that positively influence the enteric microbiota by selectively promoting growth of beneficial bacteria and 2) oral administration of probiotic bacteria which when administered in adequate amounts confer a health benefit on the host. While the complex microbiota of the adult is difficult to change in the long-term, there is greater impact of the diet on infant microbiota as this is not as stable as in adults. Decreasing excessive use of antibiotics and increasing the use of pre- and probiotics have shown to be beneficial in the prevention of several important infant diseases such as necrotizing enterocolitis and atopic eczema as well as improvement of short and long-term health. This review addresses how the composition of the gut microbiota becomes established in early life, its relevance to infant health, and dietary means by which it can be manipulated.

Probiotics and prebiotics in infant nutrition

The human colonic microflora has a central role in health and disease, being unique in its complexity and range of functions. As such, dietary modulation is important for improved gut health, especially during the highly-sensitive stage of infancy. Diet can affect the composition of the gut microflora through the availability of different substrates for bacterial fermentation. Differences in gut microflora composition and incidence of infection exist between breast-fed and formula-fed infants, with the former thought to have improved protection. Historically, this improvement has been believed to be a result of the higher presence of reportedly-beneficial genera such as the bifidobacteria. As such, functional food ingredients such as prebiotics and probiotics could effect a beneficial modification in the composition and activities of gut microflora of infants by increasing positive flora components. The prebiotic approach aims to increase resident bacteria that are considered to be beneficial for human health, e.g. bifidobacteria and lactobacilli, while probiotics advocates the use of the live micro-organisms themselves in the diet. Both approaches have found their way into infant formula feeds and aim to more closely simulate the gut microbiota composition seen during breast-feeding.

Intestinal microflora of human infants and current trends for its nutritional modulation

Diet, among other environmental and genetic factors, is currently recognised to have an important role in health and disease. There is increasing evidence that the human colonic microbiota can contribute positively towards host nutrition and health. As such, dietary modulation has been proposed as important for improved gut health, especially during the highly sensitive stage of infancy. Differences in gut microflora composition and incidence of infection occur between breast- and formula-fed infants. Human milk components that cannot be duplicated in infant formulae could possibly account for these differences. However, various functional food ingredients such as oligosaccharides, prebiotics, proteins and probiotics could effect a beneficial modification in the composition and activities of gut microflora of infants. The aim of the present review is to describe existing knowledge on the composition and metabolic activities of the gastrointestinal microflora of human infants and discuss various possibilities and opportunities for its nutritional modulation.

Immune components (IgA, IgM, IgG, immune cells) of colostrum of Bangladeshi mothers

BACKGROUND

Colostrum is the first defense for neonates. It is rich in immune components including immunoglobulins and viable immune cells. In the present study, human colostrum collected from 105 postpartum mothers was analyzed for its IgA, IgM, IgG levels, and peripheral immune cells.

METHODS

Enzyme-linked immunosorbent assay was used to analyze the serum immunoglobulin concentrations. Immune cells were estimated by counting 200 cells.

RESULTS

IgA was the dominant immunoglobulin and ranged from 2.84 to 8.69 g/L (mean 5.61 g/L). Mean IgM and IgG concentrations were 0.4 g/L (0.16-0.66 g/L) and 0.095 g/L (0.04-0.15 g/L), respectively. Neutrophil-macrophage (neu-mac) predominated in cell count (59%) followed by lymphocyte-plasma cells (lymph-plasma; 40%). The influence of maternal nutritional status, age, parity and income levels on the colostral immunological factors was studied. No significant association could be traced for immunoglobulin content, suggesting that maternal characteristics do not have any bearing on the immunoglobulin content of colostrum. Mean value of eosinophils was found to be higher among the underweight than the normal mothers (F= 3.143, r=-0.101). Maternal age was positively correlated with eosinophil (F= 3.296, r= 0.162). Concentration of neu-mac had a positive significant correlation with parity (t=-2.07, r= 0.205), while it was negatively significant for lymphocyte-plasma cells (t= 2.073, r=-0.101). However, the correlation coefficients of the immunologic parameters with other maternal characteristics were statistically insignificant.

CONCLUSION

Colostrum has enough humoral and cellular elements to protect babies. Therefore, immune protection derived from breastfeeding depends on the immunoglobulin level of the colostrum as well as the amount of colostrum ingested.

Aetiology of childhood leukemia

Leukemia is the most common cancer to affect children, accounting for approximately a third of all childhood cancers. The major morphological subtypes of leukemia, acute lymphoblastic leukemia (ALL), and acute myeloblastic leukemia (AML), are characterized by chromosomal translocations involving over 200 genes including mixed lineage leukemia (MLL), TEL, and AML1. Chromosomal translocations involving the MLL gene at 11q23 are a common feature of infant acute leukemia, found in up to 80% of all cases, and there is strong evidence that rearrangements involving the MLL gene or the TEL-AML1 gene fusion can originate in utero. As with most other cancers, the mechanism by which leukemia arises is likely to involve gene-environment interactions. Accordingly, it is important to identify exposures that cause DNA damage and induce chromosome breaks which are inadequately repaired, ultimately leading to the initiation and disease progression. Exposures acting before birth and early in life has long been thought to be important determinants of leukemia, and the list of suspected chemical, physical, and biological agents continues to increase. Unfortunately, the evidence regarding the majority of suggested exposures is limited and often contradictory, and there are areas, which clearly warrant further investigation in order to further our understanding of the aetiology of childhood leukemia.

Murine antigen-presenting cells are multifunctional in vitro biosensors for detecting the immunoactive potential of bovine milk products

Antigen-presenting cells (APCs) are multifunctional components of the immune defense system. In this study, murine APCs were used as biosensors to detect immunologically active components of bovine milk and colostrum. By measuring changes in cell surface protein markers [major histocompatibility complex II, cluster designation (CD)40, CD86] and cytokines (tumor necrosis factor-alpha and interleukin-10) associated with APC activation, we identified a number of compounds that are immunoactive. The mouse macrophage cell line MH-S offered a simple and robust target for identification of immunoactives. The assay was shown to be adaptable for measuring immunoenhancing or immunosuppressive substances. Large-scale screening of milk extracts using this bioassay has the potential to identify substances that could be developed into nutraceuticals or pharmaceutical-grade immunotherapeutics.

What do midwives and nurses in Turkey know about nutrition in the first six months of life

OBJECTIVE

to discover what midwives and nurses in Turkey know and advise about nutrition in the first 6 months of life.

DESIGN

a descriptive, cross-sectional study.

SETTING

health clinics and mother and baby health and family planning centres in the municipality of Ankara.

PARTICIPANTS

301 midwives and nurses selected by stratified, random sampling.

FINDINGS

nine questions related to the features and benefits of breast milk. The mean number of questions answered correctly was 7.55 (standard deviation [SD]=1.25). Participants agreed that the babies should be breast fed for the first 6 months of life (n=184; 61.1%) and that complementary food could be introduced at 6 months of age (n=291; 96.7%). Most participants (n=223; 74.1%) recommended that mothers who have to resume work should express and store breast milk, and their babies should be fed with it. Many participants noted that there may be one or more situations when artificial milk should be given in the first 6 months of life (n=286; 95.0%). Almost all of the participants (n=292; 97.0%) gave one or more suggestions of when breast milk was sufficient or insufficient.

CONCLUSIONS

most midwives and nurses in this research had adequate knowledge related to babies in the first 6 months of life. However, with continuing education, knowledge deficits can be corrected, and awareness of their roles and responsibilities can be increased in achieving one of Turkey's priority goals for the 21st Century, that of decreasing the baby death rate.

Causes of childhood leukaemia and lymphoma

Childhood cancer is rare comprising less than 1% of all malignancies diagnosed each year in developed countries. Leukaemia is the commonest form of cancer in children accounting for around a third of all childhood cancer, with acute lymphoblastic leukaemia (ALL) being the most prevalent. Biologically specific subtypes of ALL and acute myeloblastic leukaemia (AML), the other major morphological type of childhood leukaemia, are characterised by chromosomal changes. Whilst over 200 genes have been associated with chromosomal translocations, to date, only MLL, TEL, and AML1 have been linked with childhood leukaemia. Interestingly, there is increasing evidence to support the theory that gene rearrangements such as these may originate in utero. As with many other human diseases, both genetic and environmental factors have been implicated in the aetiology of the disease. Although much has been documented with regard to diet, smoking, alcohol consumption and recreational and prescription drug use during pregnancy, there is no consistent evidence to support a link with any of these factors and childhood leukaemia. However, findings from studies investigating prenatal and early life exposures are often based on small numbers of cases as both the type of cancer and exposure are rare. Furthermore, accurate information relating to past exposures can be difficult to obtain and is often reliant on self-reporting. To further our understanding of the aetiology of childhood leukaemia and lymphoma, there are areas which clearly warrant investigation. These include collection of parental dietary folate data combined with genetic analysis of the folate related genes, in utero exposure to DNA topoisomerase II inhibitors, and the possible effects of assisted reproduction technology on disease susceptibility.

Breastfeeding and childhood cancer

The relationship between childhood cancer and having been breastfed in infancy was investigated in the UK Childhood Cancer Study (UKCCS), a national, population-based case-control study. Analyses included 3500 children with cancer (cases) of whom 1637 were diagnosed with leukaemia, 114 with Hodgkin's disease, 228 with non-Hodgkin's lymphoma and 1521 with other cancer and 6964 controls. 62% cases and 64% controls were reported to have ever been breastfed. There was weak evidence, of borderline statistical significance, that having been breastfed was associated with a small reduction in the odds ratios for leukaemia (odds ratio = 0.89, 95% Cl 0.80-1.00, P = 0.06), and for all cancers combined (odds ratio = 0.92, 95% Cl 0.84-1.00, P = 0.05). Combining data from the UKCCS with results from other published studies showed a small reduction in the odds ratios for leukaemia, Hodgkin's disease, non-haematological cancers, and all childhood cancers combined, associated with ever having been breastfed. It is unclear whether the apparent small reduction in the odds ratio for these various types of childhood cancer is a generalized effect of breastfeeding or whether it reflects some systematic bias in the majority of studies that have investigated the question.

Breast-feeding in sub-Saharan Africa: outlook for 2000

The World Health Organization (WHO) has stressed that 1.5 million infants die annually, unnecessarily, from deprival or from insufficiency of breast milk. Hence, the need for its maximal use, very particularly in impoverished populations, such as those in sub-Saharan Africa. In many developed populations, a generation ago the practice was very low, but now it has risen considerably. In contrast, in Africa and in most developing populations, despite the far greater need for breast-feeding, the practice is tending to decrease, especially among urban mothers. While the most common reasons given concern insufficiency of breast milk and employment of mothers, the latter, especially urban mothers, are under strong and increasing pressure to use proprietary replacement foods. These are often made up unsatisfactorily and are contaminated. Also influential are the often less than enthusiastic, and confusing, attitudes of staff at clinics and hospitals, albeit, due in part to their very heavy workloads. Additionally, there is society's relatively indifferent attitude to breast-feeding. Currently, a hugely adverse factor is the danger of human immunodeficiency virus (HIV) transference from seropositive mothers to their infants - in some African countries almost half of antenatal mothers are infected. Chances of early control of the infection are remote. However, apart from this danger, and from the pressure from replacement food companies, the outlook for breast-feeding practice in many African countries is unlikely to improve significantly until greater encouragement is given from State, local and other health authorities.