The Gastrointestinal Microbiome in Infant Colic: A Scoping Review

Why do babies cry? Exploring the role of the gut microbiota in infantile colic, constipation, and cramps in the KOALA birth cohort study

Gastrointestinal symptoms are common during infancy, including infantile colic. Colic can be loosely defined as prolonged and recurrent crying without obvious cause. The cause indeed remains unclear despite much research. Results on infant nutrition are inconclusive, but prior work has linked maternal mental health to infant crying. Recently, several small studies have described associations between gut microbiota and colic. We used a larger cohort to examine the role of the microbiota in infant gastrointestinal health, while also accounting for other biopsychosocial factors. Using fecal 16S rRNA gene amplicon sequencing data from 1,012 infants in the KOALA birth cohort, we examined associations between the 1-month gut microbiota and parent-reported functional gastrointestinal symptoms throughout infancy, including colic, constipation, and cramps. These analyses were adjusted for biopsychosocial factors that were associated with symptoms in a broader analysis involving 2,665 participants. In 257 infants, we also explored associations between breastmilk human milk oligosaccharides (HMOs) and gastrointestinal symptoms. Higher relative abundance of Staphylococcus at one month was associated with less constipation in the first three months of life. Conversely, Ruminococcus gnavus group abundance was associated with more colicky symptoms, particularly between four and seven months. Breastmilk concentrations of the HMOs lacto-N-hexaose (LNH) and lacto-N-neohexaose (LNnH) were associated with less constipation in the first three months. Our results support the conclusion that gut microbiota are relevant in infantile colic and constipation. However more work is needed to elucidate the underlying mechanisms, and explore their interplay with other relevant biopsychosocial factors such as maternal mental health.

Effects of excessive Platycodon grandiflorus root on gut microbiota and host co-metabolism in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Platycodon grandiflorus root, is a widely used herb in East Asia for treating respiratory diseases, but research on its oral safety is limited.

AIM OF THE STUDY

This study examines the potential adverse gastrointestinal reactions resulting from excessive consumption of Platycodon grandiflorus root (PR) and its effects on gut microbiota and host co-metabolism.

MATERIALS AND METHODS

This study evaluated the effects of different doses (1.5, 4.5, and 7.5 g/kg/day) of PR on ICR mice through gavage. Select the 7.5 g/kg/day dosage group and the control group to assess intestinal morphology and conduct histopathological studies. Examine inflammation-related factors and tight junction proteins using WB, qPCR, and ELISA. Additionally, perform 16S rDNA sequencing and metabolomic analyses to evaluate changes in gut microbiota and endogenous metabolites. Finally, the clearance of gut microbiota with antibiotics, the effects of excessive PR on mice were investigated.

RESULTS

Excessive intake of PR can lead to mortality in mice, as well as symptoms such as intestinal flatulence and slowed intestinal transit, suggesting the occurrence of chronic intestinal pseudo-obstruction accompanied by endotoxemia. It altered both α-diversity and β-diversity in the gut microbiota of mice, with increased relative abundances of Pseudomonadota, Verrucomicrobiota, Escherichia-Shigella, Akkermansia, Bacteroides, and Klebsiella, closely linked to intestinal obstruction and bacterial overgrowth. Excessive intake of PR also resulted in metabolic disturbances in mice, particularly in the levels of metabolites such as bate-hydroxybutyrate, 5,6-dihydrouracil, uridine, isoleucine, mannitol, bate-alanine, L-cysteine, L-tyrosine, and orotic acid, which may provide insights into the side effects associated with excessive consumption of PR. Clearing the gut microbiota significantly mitigated adverse effects on the intestines and restored metabolite levels.

CONCLUSIONS

This study demonstrates that excessive PR induces gut microbiota and metabolic disruption in normal mice, with the overgrowth of Gram-negative bacteria releasing LPS that impair smooth muscle contraction, leading to adverse effects such as chronic intestinal pseudo-obstruction.

The Association of Short-Chain Fatty Acids with the Occurrence of Gastrointestinal Symptoms in Infants

Short-chain fatty acids (SCFAs) are produced by the fermentation of undigested polysaccharides; they are a group of metabolites resulting from the activity of intestinal bacteria. The main SCFAs are acetic, butyric, propionic, valeric, and caproic acid, and their levels and proportions depend on various factors. The aim of this study was to investigate the relationship between the concentration of SCFAs and the occurrence of specific gastrointestinal symptoms in infants. This study was conducted using faecal samples obtained at 1, 3, 6, and 12 months of age. The SCFA content was measured using gas chromatography. At 1 month, an association was found between butyric acid and flatulence. At 3 months, an association was found between butyric acid and flatulence/gas and between 3,4-methylovaleric acid and mucus in the stool. At 6 months, an association was found between butyric and valeric acids and flatulence. By 12 months, the gastrointestinal symptoms had decreased significantly. This study confirms that there is an association between SCFA levels and the presence of bloating, gas, mucus in the stool, and constipation in the gastrointestinal tract. Higher levels of butyric and valeric acids may lead to an increase in troublesome symptoms, such as flatulence and gas, in the first few months of life but are not associated with the occurrence of intestinal colic. The level of 3,4-methylovaleric acid is associated with the presence of allergies, whereas a decrease in acetic acid and an increase in isovaleric acid may exacerbate defecation problems in infants.

Evaluating the influence of parental atopy on the effectiveness of a maternal dairy-free diet in alleviating infantile colic: a before-and-after study

BACKGROUND

Infantile Colic (IC) poses a significant challenge for parents as it manifests through repeated and extended episodes of fussiness, crying, or irritability occurring before the age of 5 months. The precise cause of IC is currently unknown. The association between IC, a family history of atopy, and the development of individual atopy in the future remains uncertain, given conflicting findings from prior studies.

OBJECTIVES

This study aimed to investigate the impact of parental atopy on IC severity and the effectiveness of the mother's hypoallergenic Dairy-Free Diet in alleviating pain in infants with colic.

METHODS

This non-randomized trial conducted at Amirkabir Hospital in Arak, Iran, from January 2023 to October 2023, involving 206 eligible IC patients non-randomly assigned to two groups based on parental atopy history. Breastfed infants were prescribed a dairy-free diet, involving the removal of dairy products from the mother's diet. Pain severity was assessed using the FLACC scale at baseline and after one-month of intervention.

RESULTS

The research initially involved 206 subjects with an average age of 28.77 ± 9.99 days, evenly distributed based on parental atopy history. However, there was a 28.6% loss to follow-up, resulting in a final analyzed population of 147 individuals. The intervention, a maternal dairy-free diet, demonstrated a significant reduction in pain symptoms within both groups and overall (P = 0.001), with no significant difference in efficacy between infants with and without parental atopy history (P = 0.219). Parental history of atopy did not exhibit a significant association with colic pain severity (P = 0.404). The study revealed that the impact of the diet on colic severity varied, with more pronounced effects observed in cases of severe and moderate colic compared to mild cases.

CONCLUSIONS

Adopting a Dairy-Free Diet significantly reduced colic symptoms, irrespective of parental atopy history. The severity of colic appears unrelated to parental atopy, and the observed improvement with a Dairy-Free diet is potentially attributed to milk intolerance rather than milk allergy.

Early-life risk factors for both infant colic and excessive crying without colic

BACKGROUND

Infantile colic may represent gastrointestinal distress, yet most definitions emphasize excessive crying. Each may have distinct etiologies.

DESIGN/METHODS

In a pre-birth cohort, we used maternal reports of infant crying and apparent abdominal discomfort at 6mos to categorize infants as (1) unaffected (no excessive crying or colic), (2) excessive crying only, and (3) colic (abdominal discomfort +/- excessive crying). We examined associations of potential risk factors in separate models with excessive crying and colic (each vs. unaffected) using unadjusted multinomial logistic regression, and associations between count of risk factors and colic using logistic regression.

RESULTS

Of 1403 infants, 140 (10%) had excessive crying, and 346 (25%) colic. Infants that were non-Hispanic white, low birthweight, firstborn, or had a maternal history of atopy, high postpartum depressive symptoms, or persistent prenatal nausea, had a 40-80% higher relative risk of colic. Preterm birth was associated with double the risk. Being firstborn, low birthweight, and preterm birth predicted excessive crying. Infants with ≥four (vs. 0-1) of the seven identified risk factors had 3.9 times (95% CI: 2.6, 6.1) higher odds of colic.

CONCLUSIONS

Colic characterized by apparent abdominal discomfort can be phenotypically distinguished from excessive crying only. Multiple risk factors may further increase colic risk.

IMPACT

Infant colic characterized by apparent gastrointestinal distress may be phenotypically distinct from excessive crying only. Literature that defines colic only based on crying behaviors may miss important predictors. Mother-reported colic and excessive crying appear to have overlapping risk factors, with additional risk factors identified for colic. The presence of multiple risk factors increases the risk of colic, supporting a multifactorial etiology.

Compositional and functional variability of the gut microbiome in children with infantile colic

The inconsolable crying of a child for no apparent reason at an early age is a source of excitement and anxiety for parents. Previous studies have reported that crying may be caused by discomfort associated with the occupation of the intestines of the newborn by microbiota and its vital activity. We conducted a prospective observational study in which 62 newborns and their mothers were recruited. The study comprised two groups, each consisting of 15 infants with colic and 21 controls. Colic and control groups were vaginally born and exclusively breastfed. Fecal samples from children were collected over time from day 1 to 12 months. Full metagenomic sequencing of fecal samples from children and their mothers was carried out. It was determined that the trajectory of the development of the intestinal microbiome of children with colic was different from the group without colic. In the colic group, a depleted relative abundance of Bifidobacterium and enrichment of Bacteroides Clostridiales was found, while the microbial biodiversity in this group was enriched. Metabolic pathway profiling showed that the non-colic group was enriched by amino acid biosynthetic pathways, while the feces microbiome of the colic group was enriched by glycolysis metabolic pathways that correlated with the Bacteroides taxon. This study shows that infantile colic has a definite relationship with the microbiome structure of infants.

Effectiveness of a starch thickened infant formula with reduced lactose content, probiotics and prebiotics on quality of life and clinical outcome in infants with regurgitation and/or colic

Background

Regurgitation and colic are quite common in young infants, leading to a reduced quality of life (QoL) and to parental distress. Their management is challenging and aims to effectively reassure and relieve symptoms. This study aimed to assess the effectiveness over 30 days of a starch thickened formula with a reduced lactose content, Limosilactobacillus reuteri (Lactobacillus reuteri) DSM 17938 and FOS/GOS.

Methods

A real-world prospective multicenter experimental study was conducted in a before-after design within subject. Full term infants 0-5 months with regurgitation or colic or both symptoms and without intercurrent illness were included after parental informed consent and received the studied formula. The primary endpoint was the improvement in QoL using the QUALIN infant's questionnaire. Secondary endpoints were the symptoms outcome and the formula tolerance.

Results

Of the 101 infants included (age: 6.2 ± 4.3  weeks), 33 had regurgitation, 34 colic and 34 had both. At D30, the QoL score was improved in 75% of infants in per protocol analysis (n = 68; +8.2 ± 13.7; p < 0.001), more in those with colic or both symptoms. Meanwhile, in intention to treat analysis (all p < 0.001), the daily number of regurgitations decreased by 61% and the weekly number of days with colic by 63% while the daily cumulative duration of crying decreased by 82 ± 106 mn. These improvements were observed within the first week by 89 and 76% of parents, respectively.

Conclusion

The study formula associated with reassurance is shown to be quickly effective in the management of infant's regurgitation or/and colic in routine clinical practice.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT04462640.

The Association between Infant Colic and the Multi-Omic Composition of Human Milk

Infant colic is a common condition with unclear biologic underpinnings and limited treatment options. We hypothesized that complex molecular networks within human milk (i.e., microbes, micro-ribonucleic acids (miRNAs), cytokines) would contribute to colic risk, while controlling for medical, social, and nutritional variables. This hypothesis was tested in a cohort of 182 breastfed infants, assessed with a modified Infant Colic Scale at 1 month. RNA sequencing was used to interrogate microbial and miRNA features. Luminex assays were used to measure growth factors and cytokines. Milk from mothers of infants with colic (n = 28) displayed higher levels of Staphylococcus (adj. p = 0.038, d = 0.30), miR-224-3p (adj. p = 0.023, d = 0.33), miR-125b-5p (adj. p = 0.028, d = 0.29), let-7a-5p (adj. p = 0.028, d = 0.27), and miR-205-5p (adj. p = 0.029, d = 0.26) compared to milk from non-colic mother-infant dyads (n = 154). Colic symptom severity was directly associated with milk hepatocyte growth factor levels (R = 0.21, p = 0.025). A regression model involving let-7a-5p, miR-29a-3p, and Lactobacillus accurately modeled colic risk (X² = 16.7, p = 0.001). Molecular factors within human milk may impact colic risk, and provide support for a dysbiotic/inflammatory model of colic pathophysiology.

A Multiscale Spatiotemporal Model Including a Switch from Aerobic to Anaerobic Metabolism Reproduces Succession in the Early Infant Gut Microbiota

The human intestinal microbiota starts to form immediately after birth and is important for the health of the host. During the first days, facultatively anaerobic bacterial species generally dominate, such as Enterobacteriaceae. These are succeeded by strictly anaerobic species, particularly Bifidobacterium species. An early transition to Bifidobacterium species is associated with health benefits; for example, Bifidobacterium species repress growth of pathogenic competitors and modulate the immune response. Succession to Bifidobacterium is thought to be due to consumption of intracolonic oxygen present in newborns by facultative anaerobes, including Enterobacteriaceae. To study if oxygen depletion suffices for the transition to Bifidobacterium species, here we introduced a multiscale mathematical model that considers metabolism, spatial bacterial population dynamics, and cross-feeding. Using publicly available metabolic network data from the AGORA collection, the model simulates ab initio the competition of strictly and facultatively anaerobic species in a gut-like environment under the influence of lactose and oxygen. The model predicts that individual differences in intracolonic oxygen in newborn infants can explain the observed individual variation in succession to anaerobic species, in particular Bifidobacterium species. Bifidobacterium species became dominant in the model by their use of the bifid shunt, which allows Bifidobacterium to switch to suboptimal yield metabolism with fast growth at high lactose concentrations, as predicted here using flux balance analysis. The computational model thus allows us to test the internal plausibility of hypotheses for bacterial colonization and succession in the infant colon. IMPORTANCE The composition of the infant microbiota has a great impact on infant health, but its controlling factors are still incompletely understood. The frequently dominant anaerobic Bifidobacterium species benefit health, e.g., they can keep harmful competitors under control and modulate the intestinal immune response. Controlling factors could include nutritional composition and intestinal mucus composition, as well as environmental factors, such as antibiotics. We introduce a modeling framework of a metabolically realistic intestinal microbial ecology in which hypothetical scenarios can be tested and compared. We present simulations that suggest that greater levels of intraintestinal oxygenation more strongly delay the dominance of Bifidobacterium species, explaining the observed variety of microbial composition and demonstrating the use of the model for hypothesis generation. The framework allowed us to test a variety of controlling factors, including intestinal mixing and transit time. Future versions will also include detailed modeling of oligosaccharide and mucin metabolism.