Grain, Gluten, and Dietary Fiber Intake Influence Gut Microbial Diversity: Data from the Food and Microbiome Longitudinal Investigation

Gut microbiome diversity and nutrition intake in post-stroke patients

AIM

This study aimed to investigate the association between energy intake and gut microbiome diversity in patients following stroke.

METHODS

A cross-sectional study was conducted with 156 patients following stroke aged ≥65 years admitted to a rehabilitation hospital (mean age, 78 ± 7 years; 69 women). Energy intake was calculated from average food consumption during the first week after admission. Gut microbiome diversity was assessed using three indices derived from 16S rRNA sequencing of stool samples: the Shannon index, operational taxonomic unit (OTU) richness and Faith's phylogenetic diversity (PD). Sex-stratified multiple linear regression analysis evaluated the association between energy intake and gut microbiome diversity, adjusting for confounders such as age, body weight, inflammation markers, nutritional status, and medication.

RESULTS

The study included 156 patients following stroke (mean age, 78 ± 7 years; 69 women). The median energy intake was 1600 (interquartile range [IQR], 1400-1800] kcal/day for all participants. The median for gut microbiome diversity indices were Shannon index, 6.3 (IQR, 5.9-6.5); OTU richness, 217.3 (IQR, 181.9-258.1); and Faith's PD, 22.4 (IQR, 19.3-27.2). In women, energy intake was significantly positively associated with the Shannon index (β = 0.233, P = 0.026), OTU richness (β = 0.228, P = 0.036), and Faith's PD (β = 0.212, P = 0.038). In men, energy intake was significantly positively associated with the Shannon index (β = 0.230, P = 0.027), OTU richness (β = 0.211, P = 0.040), and Faith's PD (β = 0.198, P = 0.043).

CONCLUSIONS

Adequate energy intake may play an important role in preserving gut microbiome diversity in patients. Further longitudinal studies are needed to confirm these associations, clarify causality, and explore underlying mechanisms. Geriatr Gerontol Int 2025; 25: 535-542.

The gut microbiome across the lifespan: how diet modulates our microbial ecosystem from infancy to the elderly

This comprehensive review examines the impact of dietary patterns on gut microbiome composition and diversity from infancy to old age, linking these changes to age-related health outcomes. It investigates how the gut microbiome develops and changes across life stages, focusing on the influence of dietary factors. The review explores how early-life feeding practices, including breastfeeding and formula feeding, shape the infant gut microbiota and have lasting effects. In elderly individuals, alterations in the gut microbiome are associated with increased susceptibility to infections, chronic inflammation, metabolic disorders and cognitive decline. The critical role of diet in modulating the gut microbiome throughout life is emphasised, particularly the potential benefits of probiotics and fortified foods in promoting healthy ageing. By elucidating the mechanisms connecting food systems to gut health, this review provides insights into interventions that could enhance gut microbiome resilience and improve health outcomes across the lifespan.

Beneficial microbiome and diet interplay in early-onset colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer-related deaths worldwide. Although the risk of developing CRC increases with age, approximately 10% of newly diagnosed cases occur in individuals under the age of 50. Significant changes in dietary habits in young adults since industrialization create a favorable microenvironment for colorectal carcinogenesis. We aim here to shed light on the complex interplay between diet and gut microbiome in the pathogenesis and prevention of early-onset CRC (EO-CRC). We provide an overview of dietary risk factors associated with EO-CRC and contrast them with the general trends for CRC. We delve into gut bacteria, fungi, and phages with potential benefits against CRC and discuss the underlying molecular mechanisms. Furthermore, based on recent findings from human studies, we offer insights into how dietary modifications could potentially enhance gut microbiome composition to mitigate CRC risk. All together, we outline the current research landscape in this area and propose directions for future investigations that could pave the way for novel preventive and therapeutic strategies.

Microbiome-based correction for random errors in nutrient profiles derived from self-reported dietary assessments

Since dietary intake is challenging to directly measure in large-scale cohort studies, we often rely on self-reported instruments (e.g., food frequency questionnaires, 24-hour recalls, and diet records) developed in nutritional epidemiology. Those self-reported instruments are prone to measurement errors, which can lead to inaccuracies in the calculation of nutrient profiles. Currently, few computational methods exist to address this problem. In the present study, we introduce a deep-learning approach-Microbiome-based nutrient profile corrector (METRIC), which leverages gut microbial compositions to correct random errors in self-reported dietary assessments using 24-hour recalls or diet records. We demonstrate the excellent performance of METRIC in minimizing the simulated random errors, particularly for nutrients metabolized by gut bacteria in both synthetic and three real-world datasets. Additionally, we find that METRIC can still correct the random errors well even without including gut microbial compositions. Further research is warranted to examine the utility of METRIC to correct actual measurement errors in self-reported dietary assessment instruments.

Lifestyle Medicine Approach to Wound Management

Chronic wounds impact 4.5% of the US population, necessitating a comprehensive understanding of their types and underlying mechanisms. Diabetic foot ulcers (DFUs), prevalent in 25% of individuals with diabetes, contribute significantly to lower limb amputations. The pathophysiology involves neuropathy, peripheral arterial disease, impaired immunity, glycemic control, and mechanical stress. Lifestyle medicine emerges as a pivotal aspect of care, offering both prevention and treatment by integrating plant-predominant nutrition, physical activity, stress management, avoidance of harmful substances, restful sleep, and social connectedness. These interventions impact gene interactions, immune function, and tissue regeneration, playing a crucial role in chronic wound management. The standard of care involves a multidisciplinary approach, emphasizing infection and vascular management, pressure offloading, conducive wound healing environments, and lifestyle adjustments. As diabetes prevalence rises, a proactive integration of lifestyle interventions is crucial, offering a promising avenue to alleviate the growing healthcare burden associated with chronic wounds.

Impact of Novel Foods on the Human Gut Microbiome: Current Status

The microbiome is a complex ecosystem of microorganisms that inhabit a specific environment. It plays a significant role in human health, from food digestion to immune system strengthening. The "Novel Foods" refer to foods or ingredients that have not been consumed by humans in the European Union before 1997. Currently, there is growing interest in understanding how "Novel Foods" affect the microbiome and human health. The aim of this review was to assess the effects of "Novel Foods" on the human gut microbiome. Research was conducted using scientific databases, focusing on the literature published since 2000, with an emphasis on the past decade. In general, the benefits derived from this type of diet are due to the interaction between polyphenols, oligosaccharides, prebiotics, probiotics, fibre content, and the gut microbiome, which selectively promotes specific microbial species and increases microbial diversity. More research is being conducted on the consumption of novel foods to demonstrate how they affect the microbiome and, thus, human health. Consumption of novel foods with health-promoting properties should be further explored to maintain the diversity and functionality of the gut microbiome as a potential tool to prevent the onset and progression of chronic diseases.

Post-diagnosis dietary factors, supplement use and colorectal cancer prognosis: A Global Cancer Update Programme (CUP Global) systematic literature review and meta-analysis

The role of diet in colorectal cancer prognosis is not well understood and specific lifestyle recommendations are lacking. We searched for randomised controlled trials (RCTs) and longitudinal observational studies on post-diagnosis dietary factors, supplement use and colorectal cancer survival outcomes in PubMed and Embase from inception until 28th February 2022. Random-effects dose-response meta-analyses were conducted when at least three studies had sufficient information. The evidence was interpreted and graded by the CUP Global independent Expert Committee on Cancer Survivorship and Expert Panel. Five RCTs and 35 observational studies were included (30,242 cases, over 8700 all-cause and 2100 colorectal cancer deaths, 3700 progression, recurrence, or disease-free events). Meta-analyses, including 3-10 observational studies each, were conducted for: whole grains, nuts/peanuts, red and processed meat, dairy products, sugary drinks, artificially sweetened beverages, coffee, alcohol, dietary glycaemic load/index, insulin load/index, marine omega-3 polyunsaturated fatty acids, supplemental calcium, circulating 25-hydroxyvitamin D (25[OH]D) and all-cause mortality; for alcohol, supplemental calcium, circulating 25(OH)D and colorectal cancer-specific mortality; and for circulating 25(OH)D and recurrence/disease-free survival. The overall evidence was graded as 'limited'. The inverse associations between healthy dietary and/or lifestyle patterns (including diets that comprised plant-based foods), whole grains, total, caffeinated, or decaffeinated coffee and all-cause mortality and the positive associations between unhealthy dietary patterns, sugary drinks and all-cause mortality provided 'limited-suggestive' evidence. All other exposure-outcome associations provided 'limited-no conclusion' evidence. Additional, well-conducted cohort studies and carefully designed RCTs are needed to develop specific lifestyle recommendations for colorectal cancer survivors.

Diet quality and anxiety: a critical overview with focus on the gut microbiome

Anxiety disorders disproportionally affect females and are frequently comorbid with eating disorders. With the emerging field of nutritional psychiatry, focus has been put on the impact of diet quality in anxiety pathophysiology and gut microbiome underlying mechanisms. While the relationship between diet and anxiety is bidirectional, improving dietary habits could better facilitate the actions of pharmacological and psychological therapies, or prevent their use. A better understanding of how gut bacteria mediate and moderate such relationship could further contribute to develop personalized programs and inform probiotics and prebiotics manufacturing. To date, studies that look simultaneously at diet, the gut microbiome, and anxiety are missing as only pairwise relationships among them have been investigated. Therefore, this study aims at summarizing and integrating the existing knowledge on the dietary effects on anxiety with focus on gut microbiome. Findings on the effects of diet on anxiety are critically summarized and reinterpreted in relation to findings on (i) the effects of diet on the gut microbiome composition, and (ii) the associations between the abundance of certain gut bacteria and anxiety. This novel interpretation suggests a theoretical model where the relationship between diet and anxiety is mediated and/or modulated by the gut microbiome through multiple mechanisms. In parallel, this study critically evaluates methodologies employed in the nutritional field to investigate the effects of diet on anxiety highlighting a lack of systematic operationalization and assessment strategies. Therefore, it ultimately proposes a novel evidence-based approach that can enhance studies validity, reliability, systematicity, and translation to clinical and community settings.

Sex-Dependent Efficacy of Dietary Fiber in Pediatric Functional Abdominal Pain

BACKGROUND & AIMS

Functional abdominal pain disorders (FAPDs) are more prevalent in female patients. Dietary fiber may alleviate FAPD symptoms; however, whether this effect is sex dependent remains unclear. We investigated the sex dependency of dietary fiber benefit on abdominal pain in children with FAPDs and explored the potential involvement of the gut microbiome.

METHODS

In 2 cross-sectional cohorts of children with FAPDs (n = 209) and healthy control individuals (n = 105), we correlated dietary fiber intake with abdominal pain symptoms after stratifying by sex. We also performed sex-stratified and sex-interaction analyses on data from a double-blind trial in children with irritable bowel syndrome randomized to psyllium fiber (n = 39) or placebo (n = 49) for 6 weeks. Shotgun metagenomics was used to investigate gut microbiome community changes potentially linking dietary fiber intake with abdominal pain.

RESULTS

In the cross-sectional cohorts, fiber intake inversely correlated with pain symptoms in boys (pain episodes: r = -0.24, P = .005; pain days: r = -0.24, P = 0.004) but not in girls. Similarly, in the randomized trial, psyllium fiber reduced the number of pain episodes in boys (P = .012) but not in girls. Generalized linear regression models confirmed that boys treated with psyllium fiber had greater reduction in pain episodes than girls (P = .007 for fiber × sex × time interaction). Age, sexual development, irritable bowel syndrome subtype, stool form, and microbiome composition were not significant determinants in the dietary fiber effects on pain reduction.

CONCLUSIONS

Dietary fiber preferentially reduces abdominal pain frequency in boys, highlighting the importance of considering sex in future dietary intervention studies for FAPDs. (ClincialTrials.gov, Number NCT00526903).

The link between gluten intake and the risk of cancers

Gluten is a complex mixture of hundreds of related proteins, with the two major groups being gliadin and glutenin. Gliadin primarily affects the viscosity of dough, while glutenin contributes to its strength. Nowadays, there is evidence suggesting an increase in gluten exposure due to advancements in cereal technology. Consumption of gluten can lead to development of gluten-related disorders (GRDs) in susceptible individuals. Some GRDs have been strongly associated with an increased risk of developing certain types of cancer. Colorectal cancer and lymphoma are among the most commonly reported malignancies associated with GRDs. Dietary factors, including gluten intake, have been recognized as significant modifiable risk factors for the development of digestive system cancers. The present study aimed to collect current information on the effect of gluten on the incidence of cancer in the general population and among GRDs patients. Protein-Protein Interaction (PPI) Network analysis of common genes between celiac disease (CD) and cancer was also conducted.