Age-Associated Changes in Gut Microbiota and Dietary Components Related with the Immune System in Adulthood and Old Age: A Cross-Sectional Study.

The fecal microbiota plays an important role in human health, and alterations in the microbiota-host interaction seem to be involved in the ageing process. Therefore, it is of interest to develop strategies for promoting a balanced microbiota in old age in order to prevent the physiological and immune decline associated with age. However, the specific microbiota changes in the transition from adulthood to senescence are not yet well understood. Here we assessed the levels of some intestinal microorganisms and short chain fatty acids (SCFAs) across different age-groups. In total, 153 adults from four age groups (<50, 50-65, 66-80, and >80 years-old) were recruited; the levels of different bacterial groups in fecal samples were determined by quantitative polymerase chain reaction (qPCR), and those of SCFA by gas chromatography. Dietary information was collected by using a Food Frequency Questionnaire. The presence of the Bifidobacterium, Faecalibacterium, Bacteroides group, and Clostridium cluster XIVa decreased with age up to 66-80 years of age, with differences reaching statistical significance for the latter group. Interestingly, the levels of some of these microorganisms recovered in the very old age group (>80 years), with these older individuals presenting significantly higher counts of Akkermansia and Lactobacillus group than adults and the younger elderly. In addition, ageing was associated with a progressively and statistically significant reduction in the fecal concentrations of SCFAs. Dietary intakes also showed some statistically significant differences among the groups for some macro- and micronutrients. Moreover, associations of some microorganisms with age and macronutrients were also evidenced. Considering the role that fecal microbiota alterations may have in terms of impairing homeostasis and resilience, our results underline the importance of understanding the ageing and immunosenescence processes by including the microbiota perspective.

Exploring the interactions between serum free fatty acids and fecal microbiota in obesity through a machine learning algorithm.

Serum free fatty acids (FFA) are generally elevated in obesity. The gut microbiota is involved in the host energy metabolism through the regulation of body fat storage, and a link between diet, FFA and the intestinal microbiota seems to exist. Our aim was to explore the interaction among serum FFA levels, gut microbiota, diet and obesity through a model regression tree in 66 subjects (age 52.7 ±â€¯11.2 y) classified according to Body Mass Index (BMI). Total and individual FFA were analyzed by colorimetric enzymatic assay and methyl-tert-butylether-based extraction protocol (MTBE), respectively. Microbiota was determined by qPCR and diet through a food frequency questionnaire. Statistical analyses were performed, and predictive factors for obesity were obtained via classification by decision trees using machine learning methods. An obese-linked FFA profile was characterized by decreased eicosapentaenoic (EPA) and increased linoleic, gamma-linolenic and palmitic acids levels simultaneously. Serum EPA and gender were identified as the most significant variables with 100% and 80% of importance, respectively. Palmitic acid, Bifidobacterium and Faecalibacterium explained >30%, followed by Bacteroides group with 20% and docosahexaenoic acid (DHA) almost with 15% of importance. Also, the regression tree model obtained for predicting obesity, showed a non-obese-linked profile, independently of gender, with serum EPA > 0.235 µg/mL and Bacteroides > 9.055 log n° cells per g of feces. Moreover, Faecalibacterium and Bifidobacterium seemed to play an important role by complementing the levels of FFA in predicting obesity in males and females, respectively.

Could Fecal Phenylacetic and Phenylpropionic Acids Be Used as Indicators of Health Status?

Although most of the health effects attributed to polyphenols may be linked to their phenolic-derived metabolites, the role of the intestinal derived-phenolics in human health is still far from being well understood. We determined the profile of fecal phenolic-derived metabolites, microbiota, biomarkers of oxidative stress and inflammation, and daily intake of bioactive compounds in 71 elderly volunteers. Phenylacetic and phenylpropionic acids were the main phenolic metabolites present in feces. From them, phenylacetic acid was related with a more pro-oxidant and immune stimulated status, and both were negatively associated with fecal propionate, whereas phenylpropionic acid was directly related with the fecal concentration of acetate. Moreover, phenylacetic acid was negatively associated with the Bacteroides group and Clostridium cluster XIVa and positively with Lactobacillus. These results provide a rationale to explore the potential of fecal microbial phenolic-derived metabolites as possible biomarkers of health status in future studies focused on the elderly population.

Bioactive compounds from regular diet and faecal microbial metabolites.

PURPOSE: Short-chain fatty acids (SCFAs) formation by intestinal bacteria is regulated by many different factors, among which dietary fibre is currently receiving most attention. However, since fibre-rich foods are usually good dietary sources of phenolic compounds, which are also known to affect the microbiota, authors hypothesize that the regular intake of these bioactive compounds could be associated with a modulation of faecal SCFA production by the intestinal microbiota. METHODS: In this work, food intake was recorded by means of a validated Food Frequency Questionnaire. Fibres were determined using Marlett food composition tables, and phenolic compounds were obtained from Phenol-Explorer Database. Analysis of SCFA was performed by gas chromatography-flame ionization/mass spectrometry and quantification of microbial populations in faeces by quantitative PCR. RESULTS: Klason lignin and its food contributors, as predictors of faecal butyrate production, were directly associated with Bacteroides and Bifidobacterium levels, as well as lignans with Bacteroides. Also, anthocyanidins, provided by strawberries, were associated with faecal propionate and inversely related to Lactobacillus group. CONCLUSIONS: These results support the hypothesis we put forward regarding the association between some vegetable foods (strawberries, pasta, lentils, lettuce and olive oil) and faecal SCFA. More studies are needed in order to elucidate whether these associations have been mediated by the bacterial modulatory effect of the bioactive compounds, anthocyanins, lignans or Klason lignin, present in foodstuffs.

Microbiota and oxidant-antioxidant balance in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic infl ammatory disease of autoimmune nature, in which oxidative stress is implicated. AIM: Compare the concentrations of dietary and blood antioxidants, as well as gut microbiota, with serum malondialdehyde (MDA) and C reactive protein (CRP) in 21 subjects suffering from non-active systemic lupus erythematosus (SLE) and 21 age and gender-matched controls. METHODS: General biochemical parameters and CRP were determined by enzymatic methods: copper, zinc and selenium by inductively coupled plasma mass spectrometry (ICP-MS), MDA and total antioxidant capacity (TAC) by spectrophotometric methods, gut microbiota by metagenomic analyses and dietary intake by means of food frequency questionnaire. RESULTS: No significant differences were found in diet between lupus patients and the control group, with the exception of trans fatty acids intake, which was higher in patients. In addition, higher concentration of serum copper and lower of zinc in SLE were found. Serum copper was positively associated with CRP and also, this protein with the proportion of Lentisphaerae, ProteobacteriaandVerrucomicrobiain feces. Moreover, MDA levels displayed inverse correlations with the Cyanobacteriaand Firmicutesgroups, while Actinobacteria showed a positive association. The lupus subjects with presence of anti-SSA/Ro were related to higher levels of serum zinc. CONCLUSION: These results could be useful in the future to go deeper into the understanding of this complex disease.

Microbiota and oxidant-antioxidant balance in systemic lupus erythematosus / Microbiota y balance oxidante-antioxidante en lupus eritematoso sistémico

Background: Systemic lupus erythematosus (SLE) is a chronic inflammatory disease of autoimmune nature, in which oxidative stress is implicated. Aim: Compare the concentrations of dietary and blood antioxidants, as well as gut microbiota, with serum malondialdehyde (MDA) and C reactive protein (CRP) in 21 subjects suffering from non-active systemic lupus erythematosus (SLE) and 21 age and gender-matched controls. Methods: General biochemical parameters and CRP were determined by enzymatic methods: copper, zinc and selenium by inductively coupled plasma mass spectrometry (ICP-MS), MDA and total antioxidant capacity (TAC) by spectrophotometric methods, gut microbiota by metagenomic analyses and dietary intake by means of food frequency questionnaire. Results: No significant differences were found in diet between lupus patients and the control group, with the exception of trans fatty acids intake, which was higher in patients. In addition, higher concentration of serum copper and lower of zinc in SLE were found. Serum copper was positively associated with CRP and also, this protein with the proportion of Lentisphaerae, Proteobacteria and Verrucomicrobia in feces. Moreover, MDA levels displayed inverse correlations with the Cyanobacteria and Firmicutes groups, while Actinobacteria showed a positive association. The lupus subjects with presence of anti-SSA/Ro were related to higher levels of serum zinc. Conclusion: These results could be useful in the future to go deeper into the understanding of this complex disease (AU)

Introducción: el lupus eritematoso sistémico es una enfermedad inflamatoria crónica en la que está implicado el estrés oxidativo. Objetivo: evaluar la concentración de antioxidantes de la dieta y sanguíneos, así como de la microbiota sobre las concentraciones de malondialdehído y proteína C reactiva en 21 pacientes de lupus y 21 controles pareados por edad y sexo. Métodos: los parámetros bioquímicos de rutina y proteína C reactiva se determinaron a través de métodos enzimáticos: cobre, zinc y selenio por espectrometría de masas, malondialdehído y capacidad antioxidante total por métodos espectrofotométricos, la microbiota fecal por técnicas metagenómicas y la dieta a través de cuestionarios de frecuencia de consumo. Resultados: no se han observado diferencias en la dieta en los pacientes con lupus respecto al grupo control, excepto en la ingesta de ácidos grasos trans, siendo mayor en el grupo de lupus. En estas pacientes se observaron mayores niveles circulantes de cobre y menores de zinc. La concentración de cobre en suero se relacionó directamente con los niveles de proteína C reactiva y esta proteína, a su vez, con la proporción de Lentisphaerae, Proteobacteria y Verrucomicrobia en heces. Además, mientras que los niveles de malondialdehído se asociaban inversamente con la proporción de Cyanobacteria y Firmicutes, con Actinobacteria se encontró una correlación positiva. La presencia de anti-SSA/Ro en lúpicas se relaciona con mayores concentraciones de zinc. Conclusión: estos resultados podrían ser útiles para profundizar en el futuro conocimiento de esta compleja enfermedad (AU)

Different Intestinal Microbial Profile in Over-Weight and Obese Subjects Consuming a Diet with Low Content of Fiber and Antioxidants.

Obesity has been related to an increased risk of multiple diseases in which oxidative stress and inflammation play a role. Gut microbiota has emerged as a mediator in this interaction, providing new mechanistic insights at the interface between fat metabolism dysregulation and obesity development. Our aim was to analyze the interrelationship among obesity, diet, oxidative stress, inflammation and the intestinal microbiota in 68 healthy adults (29.4% normal-weight). Diet was assessed through a food frequency questionnaire and converted into nutrients and dietary compounds using food composition tables. The intestinal microbiota was assessed by quantitative PCR, fecal short chain fatty acids by gas chromatography and serum biomarkers by standard protocols. Higher levels of malondialdehyde (MDA), C reactive protein (CRP), serum leptin, glucose, fat percentage and the intestinal Lactobacillus group were found in the obese people. Cluster analysis of body mass index, fat mass, glucose, LDL/HDL ratio, leptin, MDA and CRP classified the subjects into two groups. The levels of the intestinal Bacteroides-Prevotella-Porphyromonas group were lower in the cluster and linked to a higher pro-oxidant and pro-inflammatory status, whose individuals also had lower intake of fruits, dried fruits, and fish. These results could be useful for designing strategies targeted to obesity prevention.

Adherence to a Mediterranean Diet Influences the Fecal Metabolic Profile of Microbial-Derived Phenolics in a Spanish Cohort of Middle-Age and Older People.

Despite the evidence regarding the influence of certain polyphenol food sources on the metabolic profile in feces, the association between the different phenolics provided by the diet and the fecal phenolic profile has not been elucidated. In this study, the composition of phenolic metabolites in fecal solutions was analyzed by UPLC-ESI-MS/MS in 74 volunteers. This fecal phenolic profile showed a high interindividual variation of the different compounds analyzed, phenylacetic and phenylpropionic acids being the major classes of phenolic metabolites excreted in feces. Subjects with higher adherence to a Mediterranean dietary pattern presented greater fecal concentrations of benzoic and 3-hydroxyphenylacetic acids, positively correlated with the intake of the principal classes and subclasses of polyphenols and fibers, and higher levels of Clostridium cluster XVIa and Faecalibacterium prausnitzii. These results provide a link among the Mediterranean dietary pattern, the bioactive compounds of the diet, and the fecal metabolic phenolic profile.