OBJECTIVES: To describe breastfeeding practices and investigate the influence of exclusive breastfeeding in early infancy on the risk of infant deaths, especially those attributable to respiratory infections (ARI) and diarrhea. METHODS: A prospective observational study was conducted on a birth cohort of 1677 infants who were born in slum areas of Dhaka in Bangladesh and followed from birth to 12 months of age. After enrollment at birth, the infants were visited 5 more times by 12 months of age. Verbal autopsy, based on a structured questionnaire, was used to assign a cause to the 180 reported deaths. Proportional hazards regression models were used to estimate the effect of breastfeeding practices, introduced as a time-varying variable, after accounting for other variables, including birth weight. Overall neonatal, postneonatal and infant mortality, and mortality attributable to ARI and diarrhea were measured. RESULTS: The proportion of infants who were breastfed exclusively was only 6% at enrollment, increasing to 53% at 1 month and then gradually declining to 5% at 6 months of age. Predominant breastfeeding declined from 66% at enrollment to 4% at 12 months of age. Very few infants were not breastfed, whereas the proportion of partially breastfed infants increased with age. Breastfeeding practices did not differ between low and normal birth weight infants at any age. The overall infant mortality rate was 114 deaths per 1000 live births. Compared with exclusive breastfeeding in the first few months of life, partial or no breastfeeding was associated with a 2.23-fold higher risk of infant deaths resulting from all causes and 2.40- and 3.94-fold higher risk of deaths attributable to ARI and diarrhea, respectively. CONCLUSION: The important role of appropriate breastfeeding practices in the survival of infants is clear from this analysis. The reduction of ARI deaths underscores the broad-based beneficial effect of exclusive breastfeeding in prevention of infectious diseases beyond its role in reducing exposure to contaminated food, which may have contributed to the strong protection against diarrhea deaths.

OBJECTIVES: To investigate the impact of feeding habits and daytime sugar intake on the prevalence of early childhood caries in a population where prolonged breastfeeding is a norm.

METHODS: A cross-sectional study was carried out at 18 of 102 public health centers in Tehran. During a 4-day period at each center, between 20 and 35 children aged 1-3 years were enrolled, resulting in a sample of 504 children. In structured interviews, mothers were asked to give information about their child's feeding habits, daytime sugar intake, and their family's background. Sugar intake during the night was operationalized as separately calculated burdens of nighttime breastfeeding and bottle-feeding. Clinical dental examinations followed the World Health Organization criteria. Data analysis included chi-square test, t-test, ANOVA, and logistic regression modeling.

RESULTS: Of the children, 56% were solely breastfed (mean duration 16.6 months; 95% CI 16.0-17.2), 42% were both breastfed and bottle-fed, and 2% were solely bottle-fed. Mean duration of breastfeeding for the solely breastfed 24- to 36-month olds was 22.8 months (95% CI 21.8-23.9). At bedtime, 69% were breastfed, 11% bottle-fed, and 20% were not fed at all. With respect to feeding during the night, 72% of children were breastfed, 12% were bottle-fed with milk, 1% received a bottle with water, while 15% were not fed. Early childhood caries (ECC) occurred in 3-26% of the children, depending on age group (P<0.001). The burden of milk-bottle feeding at night was a clear determinant for ECC (OR = 5.5) whereas breastfeeding per se, its duration, the burden of breastfeeding at night, and daytime sugar intake were not.

CONCLUSION: On account of its association with ECC, milk-bottle feeding at night should be limited, whereas prolonged breastfeeding appears to have no such negative dental consequences.

Stem cells in mammary tissue have been well characterised by using the mammary stem cell marker, cytokeratin (CK) 5 and the mature epithelial markers CK14, CK18 and CK19. As these markers have never been reported in cells from breastmilk, the aim of this study has been to determine whether mammary stem cells are present in expressed human breastmilk. Cultured cells from human breastmilk were studied by using immunofluorescent labelling and reverse transcription/polymerase chain reaction (RT-PCR). We found a heterogeneous population of cells with differential expression of CK5, CK14, CK18 and CK19. Further, by using the multipotent stem cell marker, nestin, we identified cells in culture that were positive only for nestin or double-positive for CK5/nestin, whereas no co-staining was observed for CK14, CK18 and CK19 with nestin. When cells isolated from breastmilk were analysed by using RT-PCR prior to culture, only nestin and CK18 were detected, thereby indicating that breastmilk contained differentiated epithelial and putative stem cells. Furthermore, fluorescence-activated cell-sorting analysis demonstrated, in breastmilk, a small side-population of cells that excluded Hoechst 33342 (a key property of multipotent stem cells). When stained for nestin, the cells in the side-population were positive, whereas those not in the side-population were negative. The presence of nestin-positive putative mammary stem cells suggests that human breastmilk is a readily available and non-invasive source of putative mammary stem cells that may be useful for research into both mammary gland biology and more general stem cell biology.

Breast milk provides important maturational stimuli to an infant's developing immune system. However, data concerning the role of breast-feeding in reducing the risk of allergic disease remain contradictory. Previous studies have centred on comparative analyses of breast milk and formula compositions. We chose a slightly different angle, whereby we focused on the effects of the chosen diet on the infant himself, comparing the immune development of formula-fed and breast-fed children. The objective of the present study was to determine how the mode of feeding affects infant immunology. Altogether, eighteen formula-fed infants with limited breast-feeding for< 3 months and twenty-nine infants who were exclusively breast-fed for>3 months were included in the study. Concentrations of interferonγ, TNF-α IL-10, IL-5, IL-4 and IL-2 were measured simultaneously from the same serum sample through use of a multiplexed flow cytometric assay at the ages of 1, 3, 6 and 12 months. Transforming growth factor β2 (TGF-β2) was measured using ELISA at the same time points. Serum TNF-α and IL-2 concentrations were significantly higher in formula-fed than in breast-fed infants during the first year of life (ANOVA, P = 0·002). The serum concentrations of TGF-β were significantly lower in formula-fed than in breast-fed infants throughout the first year of life (ANOVA, P ≤ 0·0001). Exclusive breast-feeding promotes an anti-inflammatory cytokine milieu, which is maintained throughout infancy. Such an immunological environment limits hyper-responsiveness and promotes tolerisation, possibly prohibiting the onset of allergic disease.

OBJECTIVE: To determine the association of different feeding patterns for infants (exclusive breastfeeding, predominant breastfeeding, partial breastfeeding and no breastfeeding) with mortality and hospital admissions during the first half of infancy.

METHODS: This paper is based on a secondary analysis of data from a multicentre randomized controlled trial on immunization-linked vitamin A supplementation. Altogether, 9424 infants and their mothers (2919 in Ghana, 4000 in India and 2505 in Peru) were enrolled when infants were 18-42 days old in two urban slums in New Delhi, India, a periurban shanty town in Lima, Peru, and 37 villages in the Kintampo district of Ghana. Mother-infant pairs were visited at home every 4 weeks from the time the infant received the first dose of oral polio vaccine and diphtheria-pertussis-tetanus at the age of 6 weeks in Ghana and India and at the age of 10 weeks in Peru. At each visit, mothers were queried about what they had offered their infant to eat or drink during the past week. Information was also collected on hospital admissions and deaths occurring between the ages of 6 weeks and 6 months. The main outcome measures were all-cause mortality, diarrhoea-specific mortality, mortality caused by acute lower respiratory infections, and hospital admissions.

FINDINGS: There was no significant difference in the risk of death between children who were exclusively breastfed and those who were predominantly breastfed (adjusted hazard ratio (HR) = 1.46; 95% confidence interval (CI) = 0.75-2.86). Non-breastfed infants had a higher risk of dying when compared with those who had been predominantly breastfed (HR = 10.5; 95% CI = 5.0-22.0; P<0.001) as did partially breastfed infants (HR = 2.46; 95% CI = 1.44-4.18; P = 0.001).

CONCLUSION: There are two major implications of these findings. First, the extremely high risks of infant mortality associated with not being breastfed need to be taken into account when informing HIV-infected mothers about options for feeding their infants. Second, our finding that the risks of death are similar for infants who are predominantly breastfed and those who are exclusively breastfed suggests that in settings where rates of predominant breastfeeding are already high, promotion efforts should focus on sustaining these high rates rather than on attempting to achieve a shift from predominant breastfeeding to exclusive breastfeeding.

OBJECTIVE: Childhood sleep-disordered breathing has an adverse impact on cognitive development, behavior, quality of life, and use of health care resources. Early viral infections and other immune-mediated responses may contribute to development of the chronic inflammation of the upper airway and hypertrophic upper airway lymphadenoid tissues underlying childhood sleep-disordered breathing. Breastfeeding provides immunologic protection against such early exposures. Therefore, we sought to explore whether sleep-disordered breathing severity would differ for children who were breastfed as infants.

METHODS: The parents or guardians of 196 habitually snoring children (mean +/- SD: 6.7 +/- 2.9 years old) who were undergoing overnight polysomnography at Kosair Children's Hospital Sleep Medicine and Apnea Center completed a retrospective survey on the method(s) used to feed the child as an infant.

RESULTS: Among habitually snoring children, those who were fed breast milk for at least 2 months had significantly reduced sleep-disordered breathing severity on every measure assessed, including apnea-hypopnea index, oxyhemoglobin desaturation nadir, and respiratory arousal index. Breastfeeding for longer than 5 months did not contribute additional benefits.

CONCLUSIONS: Our findings support the notion that breastfeeding may provide long-term protection against the severity of childhood sleep-disordered breathing. Future research should explore mechanism(s) whereby infant-feeding methods may affect the pathophysiology of development of childhood sleep-disordered breathing.

Complications from falciparum malaria are responsible for over one million infant deaths annually. There is as yet no clinically protective vaccine that has been developed against human malaria parasites. While several studies have demonstrated the inhibitory properties of human sera against Plasmodium falciparum, there is no reported investigation that has examined the protective effects of human breastmilk against the malaria parasite. This study demonstrates the presence of significant antibody titers to ring, trophozoite, schizont and gametocyte stages of P. falciparum in 144 Nigerian maternal milk samples and also in paired maternal and infant sera. The study also demonstrates significant in vitro growth inhibition of P. falciparum by maternal and infant sera, but most notably by breastmilk samples and breastmilk constituents, such as lactoferrin and sIgA. The results therefore suggest a protective in vivo role for breastmilk in the possible modulation of malaria frequency, severity and complications.

BACKGROUND: We previously reported beneficial effects of breast milk ingestion by infants with extremely low birth weight in the NICU on developmental outcomes at 18 months' corrected age. The objective of this study was to determine whether these effects of breast milk in infants with extremely low birth weight persisted at 30 months' corrected age.

METHODS: Nutrition data, including enteral and parenteral feeds, were prospectively collected, and 30 months' corrected age follow-up assessments were completed on 773 infants with extremely low birth weight who participated in the National Institute of Child Health and Human Development Neonatal Research Network Glutamine Trial. A total of 593 ingested some breast milk during the neonatal hospitalization, and 180 ingested none. Neonatal feeding characteristics and morbidities and 30-month interim history, neurodevelopmental outcomes, and growth parameters were analyzed. Children were divided into quintiles of breast milk volume to evaluate the effects of volume of human milk ingested during the NICU hospitalization.

RESULTS: At 30 months, increased ingestion of breast milk was associated with higher Bayley Mental Developmental Index scores, higher Bayley behavior score percentiles for emotional regulation, and fewer rehospitalizations between discharge and 30 months. There were no differences in growth parameters or cerebral palsy. For every 10 mL/kg per day increase in breast milk, the Mental Developmental Index increased by 0.59 points, the Psychomotor Developmental Index by 0.56 points, and the total behavior percentile score by 0.99 points, and the risk of rehospitalization between discharge and 30 months decreased by 5%.

CONCLUSIONS: Beneficial effects of ingestion of breast milk in the NICU persist at 30 months' corrected age in this vulnerable extremely low birth weight population. Continued efforts must be made to offer breast milk to all extremely low birth weight infants both in the NICU and after discharge.

It has been shown that milk derived from mothers with term infants is not optimal for premature babies. There is also concern about the effect of heat sterilizing breast milk. At Baragwanath Hospital, the majority of mothers remain with and care for their premature babies. Over many years, pooled pasteurized breast milk has been fed to these babies before direct breast feeding is instituted. A study was done to compare feeding pooled pasteurized breast milk and untreated own mother's milk to very low birth weight babies. There was a significantly more rapid weight gain both in terms of regaining birth weight and, from this point, to reaching a weight of 1,800 g when using untreated own mother's milk. This occurred in spite of the fact that there was little difference, especially in terms of energy content, between the two types of breast milk. This was due to the fact that the pooled pasteurized milk was also largely obtained from mothers of premature babies. It is suggested from our data that slower weight gain in the group receiving the pooled pasteurized milk could be due to the pasteurization, which probably destroys heat-labile milk lipase.

OBJECTIVE: To examine the associations of duration of exclusive breastfeeding with infections in the upper respiratory (URTI), lower respiratory (LRTI), and gastrointestinal tracts (GI) in infancy. METHODS: This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life onward in the Netherlands. Rates of breastfeeding during the first 6 months (never; partial for<4 months, not thereafter; partial for 4-6 months; exclusive for 4 months, not thereafter; exclusive for 4 months, partial thereafter; and exclusive for 6 months) and doctor-attended infections in the URTI, LRTI, and GI until the age of 12 months were assessed by questionnaires and available for 4164 subjects. RESULTS: Compared with never-breastfed infants, those who were breastfed exclusively until the age of 4 months and partially thereafter had lower risks of infections in the URTI, LRTI, and GI until the age of 6 months (adjusted odds ratio [aOR]: 0.65 [95% confidence interval (CI): 0.51-0.83]; aOR: 0.50 [CI: 0.32-0.79]; and aOR: 0.41 [CI: 0.26-0.64], respectively) and of LRTI infections between the ages of 7 and 12 months (aOR: 0.46 [CI: 0.31-0.69]). Similar tendencies were observed for infants who were exclusively breastfed for 6 months or longer. Partial breastfeeding, even for 6 months, did not result in significantly lower risks of these infections. CONCLUSIONS: Exclusive breastfeeding until the age of 4 months and partially thereafter was associated with a significant reduction of respiratory and gastrointestinal morbidity in infants. Our findings support health-policy strategies to promote exclusive breastfeeding for at least 4 months, but preferably 6 months, in industrialized countries.

OBJECTIVE--To assess the relations between breast feeding and infant illness in the first two years of life with particular reference to gastrointestinal disease.

DESIGN--Prospective observational study of mothers and babies followed up for 24 months after birth.

SETTING--Community setting in Dundee. PATIENTS--750 pairs of mothers and infants, 76 of whom were excluded because the babies were preterm (less than 38 weeks), low birth weight (less than 2500 g), or treated in special care for more than 48 hours. Of the remaining cohort of 674, 618 were followed up for two years.

INTERVENTIONS--Detailed observations of infant feeding and illness were made at two weeks, and one, two, three, four, five, six, nine, 12, 15, 18, 21, and 24 months by health visitors.

MAIN OUTCOME MEASURE--The prevalence of gastrointestinal disease in infants during follow up.

RESULTS--After confounding variables were corrected for babies who were breast fed for 13 weeks or more (227) had significantly less gastrointestinal illness than those who were bottle fed from birth (267) at ages 0-13 weeks (p less than 0.01; 95% confidence interval for reduction in incidence 6.6% to 16.8%), 14-26 weeks (p less than 0.01), 27-39 weeks (p less than 0.05), and 40-52 weeks (p less than 0.05). This reduction in illness was found whether or not supplements were introduced before 13 weeks, was maintained beyond the period of breast feeding itself, and was accompanied by a reduction in the rate of hospital admission. By contrast, babies who were breast fed for less than 13 weeks (180) had rates of gastrointestinal illness similar to those observed in bottle fed babies. Smaller reductions in the rates of respiratory illness were observed at ages 0-13 and 40-52 weeks (p less than 0.05) in babies who were breast fed for more than 13 weeks. There was no consistent protective effect of breast feeding against ear, eye, mouth, or skin infections, infantile colic, eczema, or nappy rash.

CONCLUSION--Breast feeding during the first 13 weeks of life confers protection against gastrointestinal illness that persists beyond the period of breast feeding itself.

Objective To prospectively investigate the effects of breastfeeding on the frequency and severity of infections in a well-defined infant population with adequate vaccination coverage and healthcare standards. Study design In a representative sample of 926 infants, successfully followed up for 12 months, feeding mode and all infectious episodes, including acute otitis media (AOM), acute respiratory infection (ARI), gastroenteritis, urinary tract infection, conjunctivitis and thrush, were recorded at 1, 3, 6, 9 and 12 months of life. Results Infants exclusively breastfed for 6 months, as per WHO recommendations, presented with fewer infectious episodes than their partially breastfed or non-breastfed peers and this protective effect persisted after adjustment for potential confounders for ARI (OR 0.58, 95% CI 0.36 to 0.92), AOM (OR 0.37, 95% CI 0.13 to 1.05) and thrush (OR 0.14, 95% CI 0.02 to 1.02). Prolonged exclusive breastfeeding was associated with fewer infectious episodes (r(s)=-0.07, p=0.019) and fewer admissions to hospital for infection (r(s)=-0.06, p=0.037) in the first year of life. Partial breastfeeding was not related to protective effect. Several confounding factors, including parental age and education, ethnicity, presence of other siblings, environmental tobacco smoke exposure and season of birth were demonstrated to have an effect on frequency of infections during infancy. Conclusions Findings from this large-scale prospective study in a well-defined infant population with adequate healthcare standards suggest that exclusive breastfeeding contributes to protection against common infections during infancy regarding and lessens the frequency and severity of infectious episodes. Partial breastfeeding did not seem to provide this protective effect.

BACKGROUND AND OBJECTIVE: A 2001 study revealed that $3.6 billion could be saved if breastfeeding rates were increased to levels of the Healthy People objectives. It studied 3 diseases and totaled direct and indirect costs and cost of premature death. The 2001 study can be updated by using current breastfeeding rates and adding additional diseases analyzed in the 2007 breastfeeding report from the Agency for Healthcare Research and Quality. STUDY DESIGN: Using methods similar to those in the 2001 study, we computed current costs and compared them to the projected costs if 80% and 90% of US families could comply with the recommendation to exclusively breastfeed for 6 months. Excluding type 2 diabetes (because of insufficient data), we conducted a cost analysis for all pediatric diseases for which the Agency for Healthcare Research and Quality reported risk ratios that favored breastfeeding: necrotizing enterocolitis, otitis media, gastroenteritis, hospitalization for lower respiratory tract infections, atopic dermatitis, sudden infant death syndrome, childhood asthma, childhood leukemia, type 1 diabetes mellitus, and childhood obesity. We used 2005 Centers for Disease Control and Prevention breastfeeding rates and 2007 dollars. RESULTS: If 90% of US families could comply with medical recommendations to breastfeed exclusively for 6 months, the United States would save $13 billion per year and prevent an excess 911 deaths, nearly all of which would be in infants ($10.5 billion and 741 deaths at 80% compliance). CONCLUSIONS: Current US breastfeeding rates are suboptimal and result in significant excess costs and preventable infant deaths. Investment in strategies to promote longer breastfeeding duration and exclusivity may be cost-effective.

We examined the effects of the odors from mother's milk, other mother's milk and formula milk on pain responses in newborns undergoing routine heelsticks. Forty-eight healthy infants were assigned to four groups, an own mother's breast milk odor group (Own MM), another mother's breast milk odor group (Other MM), a formula milk odor group (Formula M) and a control group. To assess infant distress in response to the heelsticks, their crying, grimacing and motor activities were recorded during the experiment as behavioral indices of the pain response. After the heelstick, the behavioral indices of the Own MM group were lower than those of other groups. By contrast, the Other MM and Formula M groups showed no significant changes compared with the Control group. We also measured salivary cortisol concentration as a biochemical index in Control and Own MM infants before and after heelstick. After the heelstick, the level of salivary cortisol was significantly increased in Control infants, but not in Own MM infants. These results suggest that pain is relieved in human newborns when they are exposed to odors from their mother's milk.

Atherosclerosis has a long pre-clinical phase with development of pathological changes in arteries of children and young adults decades before overt clinical manifestations of disease. Nutritional factors in both infancy and childhood have been shown to be important in this process and affect lifetime cardiovascular disease risk. Breast-feeding in particular is associated with benefits for long-term cardiovascular risk factors possibly as a consequence of a slower pattern of growth in breast-fed compared to formula-fed infants. In fact, the benefits of slower growth for later health and longevity, appears to be a fundamental biological phenomenon conserved across diverse animal species. The nutritional programming of atherosclerosis could therefore be regarded as a specific example of programming of human ageing as seen previously in programming of lifespan and telomere length in animals. The critical window for these effects is unknown, but evidence is accumulating for programming effects of growth from very early in infancy.

BACKGROUND: The benefits of breast-feeding for the prevention of infection in infants and young children have been widely recognized, but epidemiologic studies regarding the role of breast-feeding in protecting against Helicobacter pylori infection have produced conflicting results.

METHODS: We performed a systematic review of relevant epidemiologic studies conducted during the period 1984-2007 after abstracting data from articles that met our inclusion criteria. Study quality was assessed using the Newcastle-Ottawa scale. With use of the random effects model, we calculated the summary odds ratios (ORs) and 95% confidence intervals (CIs) for H. pylori infection according to history of breast-feeding.

RESULTS: For the 14 studies that met inclusion criteria, the summary OR for H. pylori infection was 0.78 (95% CI, 0.61-0.99; 1-sided P = .002). Nine of the 14 studies reported ORs of<1.0, and 6 of these studies reported statistically significant protective effects. Only 1 study reported a statistically significant OR of>1.0. In studies in which the subjects resided in middle- or low-income nations, the summary OR was 0.55 (95% CI, 0.33-0.93; P = .01), compared with 0.93 (95% CI, 0.73-1.19; P = .28) in studies in which subjects resided in high-income nations. The summary OR for studies that use the (13)C-urea breath test was 0.67 (95% CI, 0.32-1.39), compared with 0.91 (95% CI, 0.74-1.11) for studies that used the H. pylori IgG serologic test. We found no statistically significant dose-dependent protective effect against H. pylori associated with increasing duration of breast-feeding.

CONCLUSIONS: Breast-feeding is protective against H. pylori infection, especially in middle- and low-income nations.

The balance between free radical production and antioxidant defenses in the body has important systemic and oral health implications. There is convincing evidence that breastmilk containing antioxidants is important in the prevention of diseases in infancy. This study compared the total antioxidant concentration of human breastmilk expressed at different stages of lactation, stored at various temperatures and durations. Expressed breastmilk (EBM) samples of the third, seventh and 30th day were collected from women who had term and preterm deliveries (n = 20). Another cohort of women (n = 20) was also assessed; these women were more than five months postpartum and lactating. The total antioxidant capacity (TAC) of EBM was assessed at zero hours at room temperature, at 48 hours, one week post-refrigeration (4 degrees C), and freezing (-8 degrees C) respectively using the phosphomolybdenum method. The highest antioxidant levels were found in colostrum. The TAC of EBM reduced with time and at post-refrigeration and after freezing (p<0.0005). No significant difference in the mean TAC was observed between the EBM samples obtained from women with either term or preterm deliveries. The progressive loss of antioxidant content of EBM emphasizes the need of awareness and curtailment of the practice of storing and later use of EBM.

BACKGROUND:According to data from animal and in vitro studies, transforming growth factor-beta (TGF-beta) has a crucial effect on 2 essential parts of the mucosal immune system: IgA production and oral tolerance induction.

OBJECTIVE:We sought to ascertain whether TGF-beta in breast milk is associated with specific IgA production and atopic disease in human subjects.

METHODS:Forty-seven infants with several atopic family members were followed during their first year of life. The concentrations of TGF-beta1 and TGF-beta2 in maternal colostrum, mature milk, and the infants' sera were determined. The enzyme-linked immunospot assay was used to assess the infants' specific IgA production in response to beta-lactoglobulin, casein, gliadin, and ovalbumin.

RESULTS:At 12 months, atopic dermatitis was confirmed in 29 of 47 infants; in 11, atopic disease had begun during exclusive breast-feeding (preweaning onset), whereas in 18 the disease manifested itself after weaning (postweaning onset). The concentrations of both TGF-beta1 and TGF-beta2 were higher in maternal colostrum, but not in mature milk and infants' serum, in infants with postweaning-onset atopic disease compared with those with preweaning-onset disease (P =.0008 and P =. 015, respectively). The concentration of TGF-beta2 was, and that of TGF-beta1 tended to be, higher in the colostrum of mothers whose infants had specific IgA-secreting cells at 3 months in response to at least one of the dietary antigens tested compared with those who did not have such cells (P =.048 and P =.076, respectively).

CONCLUSION:TGF-beta in colostrum may prevent the development of atopic disease during exclusive breast-feeding and promote specific IgA production in human subjects.