Father’s Day Spotlight: The Male Microbiome

Early gut microbial colonization in infants is shaped by contributions from both mothers and fathers. Using two longitudinal metagenomic datasets, researchers found that fathers consistently provide a stable source of microbial strains to their infants regardless of delivery mode, with their contribution approaching that of mothers by the infant’s first year. However, in cesarean-born infants, natural maternal microbial transmission is disrupted. To address this, maternal fecal microbiota transplantation (FMT) was shown to significantly enhance mother-infant microbial strain sharing, promote the growth of beneficial bacteria, and reduce colonization by pathogens (Dubois et al., 2022). These findings highlight the complex, multifactorial nature of early-life microbiota development and demonstrate how both paternal contributions and maternal FMT can help address disruptions caused by medical interventions.

The concept of the 'microgenderome' emphasizes how sex differences influence the gut microbiota’s role in autoimmune and neuro-immune conditions. A study on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) found sex-specific interactions between gut bacteria (e.g., Clostridium, Streptococcus, Lactobacillus and Enterococcus) and ME/CFS symptoms, such as neurological and immune issues. Despite similar microbial compositions across sexes, these bacteria showed distinct effects in men and women (Wallis et al., 2016). This supports the importance of considering sex differences in microbiome research, particularly for chronic conditions, highlighting the need for sex-specific therapeutic approaches.

In men with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)—a long-term illness marked by profound fatigue, brain fog, and immune dysfunction—gut bacteria like Lactobacillus and Streptococcus appear to interact differently than they do in women. Lactobacillus was linked to more severe neurological, pain, and mood symptoms in men, despite being present at similar levels across sexes. Likewise, Streptococcus correlated with worsened symptoms related to sleep, energy, immunity, and gut health in men, while showing a protective trend in women (Wallis et al., 2016). Such sex-specific responses to gut microbes suggest the male microbiome may play a unique role in symptom expression for chronic conditions like ME/CFS.

Moderate aerobic exercise can improve more than just fitness—it may also benefit gut health in men. In a study of non-obese, previously sedentary adult males with similar diets, those who exercised for 10 weeks (150 minutes per week at 60–65% of VO₂peak) showed significant improvements in cardiorespiratory fitness. While overall gut microbiome diversity didn’t shift dramatically, specific bacterial changes were noted, including increases in certain genera like Streptococcus and members of the Clostridiales order. Microbial diversity was positively linked with fitness levels (VO₂peak) and negatively linked with BMI (Resende et al., 2021). Key gut bacteria like Roseburia and Odoribacter were associated with better aerobic capacity, showing how physical activity, independent of diet, can shape the male gut microbiome in potentially beneficial ways.

As men age, changes in nutrition and metabolism are linked to increased risk of chronic conditions like diabetes and cardiovascular disease. A study examining postprandial bile-acid response and its effects on energy metabolism found significant differences between young and elderly men. The elderly men showed reduced levels of bile acids like glycine-conjugated CDCA and UDCA, which play a role in digestion and fat absorption. Alongside this, the microbiome of elderly men displayed higher abundances of specific bacteria such as Ruminiclostridium and Marvinbryantia, and they experienced lower food intake, reduced fat-free mass, and increased cholesterol levels. These shifts in bile-acid response and gut microbiome composition may contribute to aging-related metabolic decline, malnutrition and Sarcopenia in men (Majait et al., 2024). Understanding these changes is crucial in addressing the unique microbiome dynamics of aging in men and their broader health implications.

From infancy to adulthood, fathers play a surprising and crucial role in shaping our microbiome ecology. Paternal microbes contribute to infant gut health, and as men age, their own microbiome evolves, influencing everything from chronic conditions to exercise performance.