Maternal nutrition and its influence affecting the development of infant gut microbiota in Hong Kong

Abstract

The infant gut microbiome plays a vital role in health. The disruption of early colonization may increase the risk of diseases and inflammatory immune response. Maternal nutrition and early infant feeding mode affect infant gut microbiota development. Breast milk and its alternatives are generally the only food for infants in the first 4 - 6 months. Breast milk contains human milk oligosaccharides (HMO) and milk microbiota, which may bring health benefits to infants. Research studies showed that maternal nutrition may also affect the HMO content in breast milk. There were studies on the influence of maternal diet during pregnancy on infant gut microbiota, yet the effects of maternal diet during lactation were scarce. And the information related to gut microbiota development and its association with maternal nutrition and HMO in the breast milk of Hong Kong infants was limited. The objectives of this study are: Identify the characteristic of the maternal diet during pregnancy and lactation in Hong Kong; Examine the development of the gut microbiota of infants in Hong Kong during the first year of life; Investigate the effects of maternal diet and early feeding practice on infant gut microbiota and assess the HMO concentration in breast milk and its correlation between maternal diet and infant gut microbiota. In this research study, pregnant and lactation women were recruited for diet assessment by Food Frequency Questionnaire and 3-day diet record, respectively, to assess the maternal nutritional status during pregnancy and lactation in Hong Kong. Infant fecal and breast milk samples were collected to study the gut microbiota development in Hong Kong infants, HMO in breast milk, and if maternal nutrition influences the HMO concentration in breast milk and infant gut microbiota development. The diet analysis showed that the average intake of vegetables, fruits, and dairy products in pregnant and lactating women was insufficient. One of the major problems is inadequate dietary fiber intake. The majority of the pregnant and lactating women had less than 50% of the recommended dietary fiber intake. Since most mothers took nutritional supplements during lactation, most micronutrient requirements except Vitamin A and Calcium could be met. 16S rDNA sequencing was conducted to analyze the gut microbiota development in infants in Hong Kong during the first year. Alpha diversity of infant gut microbiota was lower at two months of age than those at older ages. The phyla Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria were the dominant bacteria across the first year. In addition, a higher abundance of Bifidobacterium in the fecal samples were detected in the group of exclusively breastfed infants at month 2 and 4. However, this observation disappeared from the 6th month and this result could be due to the changes in the gut microbiota initiated by the introduction of solid food, which gradually reduced the profound effect of breastfeeding. Correlational analyses on maternal diet during lactation and infant gut microbiota were conducted. Total fiber intake was positively associated with the Family Tannerellaceae. Intake of medium-chain saturated some fatty acids was positively correlated genera Escherichia-shigella. There was also a significant positive association between polyunsaturated fatty acid intake and Klebsiella. Escherichia and Klebsiella are linked with chronic low-grade inflammation. A maternal diet with lower fat content may be beneficial to infants. Our results showed that the HMO concentration was dynamic throughout the lactation period, and the most abundant HMO was 2′-fucosyllactose (2′FL). Lacto-N-neotetraose (LNnT) was the highest HMO concentration in breast milk at month 2 and reduced afterward. Total HMO concentration reduced throughout the lactation period. In our study, dietary fiber intake, including soluble and insoluble dietary fiber, was found to have a positive correlation with LNnT, while fruit intake was associated positively with 2FL in human milk. The result implied that high fiber or fruit intake might associate with a high level of LNnT and 2′FL in breast milk. However, the fruit and dietary fiber intake in Hong Kong during lactation was low. To conclude, infant gut microbiota development is variable and shaped by different factors, including maternal diet and early feeding mode. The findings of this study could provide scientific evidence to draw the attention of public health to pay attention to adopt a healthy diet during pregnancy and lactation, which promotes good quality breast milk that benefits the development of healthy gut microbiota in Hong Kong infants.