Obesity is a global pandemic complex to treat due to its multifactorial pathogenesis—an unhealthy lifestyle, neuronal and hormonal mechanisms, and genetic and epigenetic factors are involved. Scientific evidence supports the idea that obesity and metabolic consequences are strongly related to changes in both the function and composition of gut microbiota, which exert an essential role in modulating energy metabolism. Modifications of gut microbiota composition have been associated with variations in body weight and body mass index. Lifestyle modifications remain as primary therapy for obesity and related metabolic disorders. New therapeutic strategies to treat/prevent obesity have been proposed, based on pre- and/or probiotic modulation of gut microbiota to mimic that found in healthy non-obese subjects. Based on human and animal studies, this review aimed to discuss mechanisms through which gut microbiota could act as a key modifier of obesity and related metabolic complications. Evidence from animal studies and human clinical trials suggesting potential beneficial effects of prebiotic and various probiotic strains on those physical, biochemical, and metabolic parameters related to obesity is presented. As a conclusion, a deeper knowledge about pre-/probiotic mechanisms of action, in combination with adequately powered, randomized controlled follow-up studies, will facilitate the clinical application and development of personalized healthcare strategies.

Disturbances of diet during pregnancy and early postnatal life may impact colonization of gut microbiota during early life, which could influence infant health, leading to potential long-lasting consequences later in life. This is a nonsystematic review that explores the recent scientific literature to provide a general perspective of this broad topic. Several studies have shown that gut microbiota composition is related to changes in metabolism, energy balance, and immune system disturbances through interaction between microbiota metabolites and host receptors by the gut-brain axis. Moreover, recent clinical studies suggest that an intestinal dysbiosis in gut microbiota may result in cognitive disorders and behavioral problems. Furthermore, recent research in the field of brain imaging focused on the study of the relationship between gut microbial ecology and large-scale brain networks, which will help to decipher the influence of the microbiome on brain function and potentially will serve to identify multiple mediators of the gut-brain axis. Thus, knowledge about optimal nutrition by modulating gut microbiota-brain axis activity will allow a better understanding of the molecular mechanisms involved in the crosstalk between gut microbiota and the developing brain during critical windows. In addition, this knowledge will open new avenues for developing novel microbiota-modulating based diet interventions during pregnancy and early life to prevent metabolic disorders, as well as neurodevelopmental deficits and brain functional disorders.

Recent evidence has disclosed a connection between gut microbial glycosidase activity and adiposity in obese. Here, we measured microbial α-glucosidase and β-galactosidase activities and sorted fluorescently labeled β-galactosidase containing (βGAL) microorganisms in faecal samples of eight lean and thirteen obese adolescents that followed a controlled calorie restriction program during one year. β-galactosidase is a highly distributed functional trait, mainly expressed by members of Blautia, Bacteroides, Alcaligenes, Acinetobacter and Propionibacterium. Only long-term calorie restriction induced clear changes in the microbiota of obese adolescents. Long-term calorie restriction induced significant shifts in total and βGAL gut microbiota, reducing the Firmicutes:Bacteroidetes ratio and enhancing the growth of beneficial microorganisms such as Bacteroides, Roseburia, Faecalibacterium and Clostridium XIVa. Moreover, the structure and composition of βGAL community in obese after long-term calorie restriction was highly similar to that of lean adolescents. However, despite this high compositional similarity, microbial metabolic performance was different, split in two metabolic states at a body mass index value of 25. Our study shows that calorie restriction is a strong environmental force reshaping gut microbiota though its metabolic performance is linked to host's adiposity, suggesting that functional redundancy and metabolic plasticity are fundamental properties of gut microbial ecosystem.

Recently, a number of studies have demonstrated the existence of a link between the emotional and cognitive centres of the brain and peripheral functions through the bi-directional interaction between the central nervous system and the enteric nervous system. Therefore, the use of bacteria as therapeutics has attracted much interest. Recent research has found that there are a variety of mechanisms by which bacteria can signal to the brain and influence several processes in relation to neurotransmission, neurogenesis, and behaviour. Data derived from both in vitro experiments and in vivo clinical trials have supported some of these new health implications. While recent molecular advancement has provided strong indications to support and justify the role of the gut microbiota on the gut–brain axis, it is still not clear whether manipulations through probiotics and prebiotics administration could be beneficial in the treatment of neurological problems. The understanding of the gut microbiota and its activities is essential for the generation of future personalized healthcare strategies. Here, we explore and summarize the potential beneficial effects of probiotics and prebiotics in the neurodevelopmental process and in the prevention and treatment of certain neurological human diseases, highlighting current and future perspectives in this topic.

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Children born to obese mothers are at increased risk for obesity, but the mechanisms behind this association are not fully understood. Our study aimed to investigate differences in the functions encoded by the microbiome of infants at 18 months of age when the transition from early infant-feeding to solid family foods is established. To investigate the impact of maternal prepregnancy body mass index on infants' gut microbiome, faecal samples from infants born to normoweight (n = 21) and obese mothers (n = 18) were analysed by 16S rRNA gene sequencing and a functional-inference-based microbiome analysis. Our results indicated that Firmicutes was significantly enriched in infants born to normoweight mothers whereas Bacteroidetes was significantly enriched in infants born to obese women. In both microbiomes, the greatest number of genes (>50%) that were assigned a function encoded for proteins involved in "metabolism" among tier 1 KEGG Orthology (KO) categories. At lower KO functional categories, the microbiome of infants born to normoweight mothers was characterized by a significant enrichment in the abundances of "pentose phosphate pathway" (p = 0.037), "lysine biosynthesis" (p = 0.043), "glycerolipid metabolism" (p = 0.042), and "C5-branched dibasic acid metabolism" (p = 0.045). Notably, the microbiome of infants born to obese mothers was significantly enriched in "streptomycin biosynthesis" (p = 0.047), "sulphur metabolism" (p = 0.041), "taurine and hypotaurine metabolism" (p = 0.036), and "lipopolysaccharide biosynthesis" (p = 0.043). In summary, our study showed that maternal prepregnancy obesity may imprint a selective gut microbial composition during late infancy with distinct functional performances.

While a wide knowledge exists on the effects of breast milk or infant formula on growth and infant development, less attention has been paid to the importance of complementary feeding (CF). This review focuses on current recommendations for optimal introduction of CF in healthy full-term European infants and discusses the potential impact of this type of feeding on health outcomes. Overall, exclusive breastfeeding is recommended at least for 4 months and preferable for 6 months, followed by the introduction of CF alongside breast milk; infants’ nutrient requirements must meet the differences between nutrients provided by breast milk and the estimated total needs. There is growing evidence that healthy feeding practices during the CF period have positive short- and long-term effects on optimal growth, body composition, neurodevelopment, healthy food preferences, and gut microbiota composition and function; adequate and healthy CF may also diminish the risk of infections, allergies, type 1 diabetes mellitus, as well as celiac and non-communicable diseases. Following the expert recommendations, the design of nutritional strategies must encourage parents to provide a healthy lifestyle for their offspring. Future research should aim to optimize timing, content, and methods of CF; furthermore, it is necessary to explore future CF-targeted health-promoting strategies in early life (appetite regulation, eating patterns, eating behavior, gut dysbiosis, etc.) to prevent growth/obesity outcomes, immune system related-diseases or non-communicable diseases in later life.

The evolutional trajectory of gut microbial colonization from birth has been shown to prime for health later in life. Here, we combined cultivation-independent 16S rRNA gene sequencing and metaproteomics to investigate the functional maturation of gut microbiota in faecal samples from full-term healthy infants collected at 6 and 18 months of age. Phylogenetic analysis of the metaproteomes showed that Bifidobacterium provided the highest number of distinct protein groups. Considerable divergences between taxa abundance and protein phylogeny were observed at all taxonomic ranks. Age had a profound effect on early microbiota where compositional and functional diversity of less dissimilar communities increased with time. Comparisons of the relative abundances of proteins revealed the transition of taxon-associated saccharolytic and fermentation strategies from milk and mucin-derived monosaccharide catabolism feeding acetate/propanoate synthesis to complex food-derived hexoses fuelling butanoate production. Furthermore, co-occurrence network analysis uncovered two anti-correlated modules of functional taxa. A low-connected Bifidobacteriaceae-centred guild of facultative anaerobes was succeeded by a rich club of obligate anaerobes densely interconnected around Lachnospiraceae, underpinning their pivotal roles in microbial ecosystem assemblies. Our findings establish a framework to visualize whole microbial community metabolism and ecosystem succession dynamics, proposing opportunities for microbiota-targeted health-promoting strategies early in life.