Choline is a water-soluble nutrient essential for human life. Gut microbial metabolism of choline results in the production of trimethylamine (TMA), which, upon absorption by the host is converted into trimethylamine-N-oxide (TMAO) in the liver. A high accumulation of both components is related to cardiovascular disease, inflammatory bowel disease, non-alcoholic fatty liver disease, and chronic kidney disease. However, the relationship between the microbiota production of these components and its impact on these diseases still remains unknown. In this review, we will address which microbes contribute to TMA production in the human gut, the extent to which host factors (e.g., the genotype) and diet affect TMA production, and the colonization of these microbes and the reversal of dysbiosis as a therapy for these diseases.

Nonalcoholic steatohepatitis (NASH) is one of the most prevalent diseases globally. A high-fat, high-cholesterol (HFHC) diet leads to an early NASH model. It has been suggested that gut microbiota mediates the effects of diet through the microbiota–gut–brain axis, modifying the host’s brain metabolism and disrupting cognition. Here, we target NASH-induced cognitive damage by testing the impact of environmental enrichment (EE) and the administration of either Lacticaseibacillus rhamnosus GG (LGG) or Akkermansia muciniphila CIP107961 (AKK). EE and AKK, but not LGG, reverse the HFHC-induced cognitive dysfunction, including impaired spatial working memory and novel object recognition; however, whereas AKK restores brain metabolism, EE results in an overall decrease. Moreover, AKK and LGG did not induce major rearrangements in the intestinal microbiota, with only slight changes in bacterial composition and diversity, whereas EE led to an increase in Firmicutes and Verrucomicrobia members. Our findings illustrate the interplay between gut microbiota, the host’s brain energy metabolism, and cognition. In addition, the findings suggest intervention strategies, such as the administration of AKK, for the management of the cognitive dysfunction related to NASH.

Metabolism and nutrition have a significant role in epigenetic modifications such as DNA methylation, which can influence gene expression. Recently, it has been suggested that bioactive nutrients and gut microbiota can alter DNA methylation in the central nervous system (CNS) through the gut–brain axis, playing a crucial role in modulating CNS functions and, finally, behavior. Here, we will focus on the effect of metabolic signals in shaping brain DNA methylation during adulthood. We will provide an overview of potential interactions among diet, gastrointestinal microbiome and epigenetic alterations on brain methylation and behavior. In addition, the impact of different diet challenges on cytosine methylation dynamics in the adult brain will be discussed. Finally, we will explore new ways to modulate DNA hydroxymethylation, which is particularly abundant in neural tissue, through diet.

Non-alcoholic steatohepatitis (NASH) is one of the most prevalent diseases worldwide. While it has been suggested to cause nervous impairment, its neurophysiological basis remains unknown. Therefore, the aim of this study is to unravel the effects of NASH, through the interrelationship of liver, gut microbiota, and nervous system, on the brain and human behavior. To this end, 40 Sprague-Dawley rats were divided into a control group that received normal chow and a NASH group that received a high-fat, high-cholesterol diet. Our results show that 14 weeks of the high-fat, high-cholesterol diet induced clinical conditions such as NASH, including steatosis and increased levels of ammonia. Rats in the NASH group also demonstrated evidence of gut dysbiosis and decreased levels of short-chain fatty acids in the gut. This may explain the deficits in cognitive ability observed in the NASH group, including their depressive-like behavior and short-term memory impairment characterized in part by deficits in social recognition and prefrontal cortex-dependent spatial working memory. We also reported the impact of this NASH-like condition on metabolic and functional processes. Brain tissue demonstrated lower levels of metabolic brain activity in the prefrontal cortex, thalamus, hippocampus, amygdala, and mammillary bodies, accompanied by a decrease in dopamine levels in the prefrontal cortex and cerebellum and a decrease in noradrenalin in the striatum. In this article, we emphasize the important role of ammonia and gut-derived bacterial toxins in liver-gut-brain neurodegeneration and discuss the metabolic and functional brain regional deficits and behavioral impairments in NASH.

Social media significantly impacts body image perception, particularly on visually driven platforms that propagate idealized, edited images. These platforms reinforce unrealistic beauty standards, contributing to body dissatisfaction and mental health issues such as anxiety and eating disorders. Movements like body positivity advocate for diverse body acceptance and challenge these ideals, yet questions remain about its long-term efficacy in reshaping body image perceptions and promoting psychological wellness. A systematic review and meta-analysis were conducted following PRISMA guidelines, analyzing studies published until 2024 across PubMed, Scopus, ScienceDirect, and Web of Science. Fifty-six studies examining the effects of body-positive content on social media were reviewed, including experimental and observational designs addressing short- and long-term impacts. Nineteen studies were excluded from the meta-analysis due to unsuitable data or lack of control groups. Meta-analyses of effect sizes between experimental and control groups were performed using R software. The meta-analysis found that body-positive content improves body satisfaction and emotional well-being immediately, especially when highlighting diverse representations and self-acceptance. Longitudinal studies reported sustained improvements in body satisfaction with consistent exposure. Significant gains in body appreciation as a trait were observed, while state-based measures showed no significant effects. Variables like body dissatisfaction and functionality also lacked significant changes. Although body-positive content reduces some harmful effects of conventional beauty standards, its influence on body surveillance and social comparison remains limited. Study variability underscores the need for targeted approaches to optimize its impact on diverse populations. Body-positive social media content shows promise in improving body satisfaction, appreciation, and mood in the short term. However, further research is required to clarify its long-term effects, develop standardized assessment methods, and identify the most effective strategies for diverse demographic groups. This research is vital to fostering healthier, more inclusive body image perceptions in the digital age. Social media plays a significant role in shaping how we view our bodies, particularly through platforms that share idealized, edited images. These sites often reinforce unrealistic beauty standards, leading to body dissatisfaction and mental health issues, such as anxiety and eating disorders. In response, movements like body positivity aim to promote the acceptance of all body types and challenge these harmful ideals. However, it remains unclear whether body-positive content can create lasting changes in body image perceptions and overall mental health. A systematic review and meta-analysis were conducted to evaluate the effects of body-positive content on social media. Studies from PubMed, Scopus, ScienceDirect, and Web of Science were included, covering both short- and long-term impacts. Out of the 56 studies reviewed, 19 were excluded due to unsuitable data or missing control groups. The remaining studies were analyzed for effect sizes between experimental and control groups using R software. The findings showed that body-positive content significantly improved body satisfaction and emotional well-being in the short term, especially when the content emphasized diverse body representations and self-acceptance. Long-term studies indicated that these improvements were sustained with ongoing exposure. While body appreciation as a personal trait improved, changes in body dissatisfaction and functionality were less significant. Although body-positive content can counteract some of the negative effects of traditional beauty standards, it had limited impact on reducing body surveillance and social comparison. The variability in study results suggests the need for more tailored approaches. Body-positive content on social media has the potential to improve body satisfaction and mood in the short term, but further research is necessary to understand its long-term impact. Future studies should explore which strategies work best for different groups to promote healthier, more inclusive body image perceptions in the digital age.

Aging is inevitable and it is one of the major contributors to cognitive decline. However, the mechanisms underlying age-related cognitive decline are still the object of extensive research. At the biological level, it is unknown how the aging brain is subjected to progressive oxidative stress and neuroinflammation which determine, among others, mitochondrial dysfunction. The link between mitochondrial dysfunction and cognitive impairment is becoming ever more clear by the presence of significant neurological disturbances in human mitochondrial diseases. Possibly, the most important lifestyle factor determining mitochondrial functioning is nutrition. Therefore, with the present work, we review the latest findings disclosing a link between nutrition, mitochondrial functioning and cognition, and pave new ways to counteract cognitive decline in late adulthood through diet.