Fecal Metagenomics to Identify Biomarkers of Food Intake in Healthy Adults: Findings from Randomized, Controlled, Nutrition Trials.

BACKGROUND: Undigested components of the human diet affect the composition and function of the microorganisms present in the gastrointestinal tract. Techniques like metagenomic analyses allow researchers to study functional capacity, thus revealing the potential of using metagenomic data for developing objective biomarkers of food intake. OBJECTIVES: As a continuation of our previous work using 16S and metabolomic datasets, we aimed to utilize a computationally intensive, multivariate, machine-learning approach to identify fecal KEGG (Kyoto encyclopedia of genes and genomes) Orthology (KO) categories as biomarkers that accurately classify food intake. METHODS: Data were aggregated from 5 controlled feeding studies that studied the individual impact of almonds, avocados, broccoli, walnuts, barley, and oats on the adult gastrointestinal microbiota. Deoxyribonucleic acid from preintervention and postintervention fecal samples underwent shotgun genomic sequencing. After preprocessing, sequences were aligned and functionally annotated with Double Index AlignMent Of Next-generation sequencing Data v2.0.11.149 and MEtaGenome ANalyzer v6.12.2, respectively. After the count normalization, the log of the fold change ratio for resulting KOs between pre- and postintervention of the treatment group against its corresponding control was utilized to conduct differential abundance analysis. Differentially abundant KOs were used to train machine-learning models examining potential biomarkers in both single-food and multi-food models. RESULTS: We identified differentially abundant KOs in the almond (n = 54), broccoli (n = 2474), and walnut (n = 732) groups (q < 0.20), which demonstrated classification accuracies of 80%, 87%, and 86% for the almond, broccoli, and walnut groups using a random forest model to classify food intake into each food group's respective treatment and control arms, respectively. The mixed-food random forest achieved 81% accuracy. CONCLUSIONS: Our findings reveal promise in utilizing fecal metagenomics to objectively complement self-reported measures of food intake. Future research on various foods and dietary patterns will expand these exploratory analyses for eventual use in feeding study compliance and clinical settings.

Honey Varietals Differentially Impact Bifidobacterium animalis ssp. lactis Survivability in Yogurt through Simulated In Vitro Digestion.

BACKGROUND: Bifidobacterium animalis ssp. lactis DN-173 010/CNCM I-2494 (B. animalis) is a probiotic strain commonly added to yogurt. Yogurt and honey are a popular culinary pairing. Honey improves bifidobacteria survival in vitro. However, probiotic survival in yogurt with honey during in vitro digestion has not been investigated. OBJECTIVES: The study aimed to evaluate the effects of different honey varietals and concentrations on B. animalis survivability in yogurt through in vitro digestion. METHODS: Yogurt with honey or control-treated samples underwent in vitro simulated oral, gastric, and intestinal digestion. B. animalis cells were enumerated on de Man Rogosa and Sharpe (MRS) medium followed by an overlay with a modified selective MRS medium; all underwent anaerobic incubation. B. animalis were enumerated predigestion and after oral, gastric, and intestinal digestion. There were 2 study phases: Phase 1 tested 4 honey varietals at 20% wt/wt per 170 g yogurt, and Phase 2 tested 7 dosages of clover honey (20, 14, 10, 9, 8, 6, and 4% wt/wt) per 170 g yogurt. RESULTS: Similar B. animalis counts were observed between all treatments after oral and gastric digestion (<1 Log colony forming units (CFU)/g probiotic reduction). Higher B. animalis survivability was observed in yogurt with clover honey after exposure to simulated intestinal fluids (∼3.5 Log CFU/g reduction; P < 0.05) compared to all control treatments (∼5.5 Log CFU/g reduction; P < 0.05). Yogurt with 10-20% wt/wt clover honey increased B. animalis survivability after simulated in vitro digestion (≤ ∼4.7 Log CFU/g survival; P < 0.05). CONCLUSIONS: Yogurt with added honey improves probiotic survivability during in vitro digestion. The effective dose of clover honey in yogurt was 10-20% wt/wt per serving (1-2 tablespoons per 170 g yogurt) for increased probiotic survivability during in vitro digestion.

Honey Added to Yogurt with Bifidobacterium animalis subsp. lactis DN-173 010/CNCM I-2494 Supports Probiotic Enrichment but Does Not Reduce Intestinal Transit Time in Healthy Adults: A Randomized, Controlled, Crossover Trial.

BACKGROUND: Honey improves probiotic survival in vitro. However, if this effect translates to humans has not been investigated. OBJECTIVES: We aimed to determine effects of honey plus yogurt containing the probiotic Bifidobacterium animalis subsp. lactis DN-173 010/CNCM I-2494 (B. animalis) on intestinal transit time, probiotic enrichment, digestive health, mood, and cognition in adults. METHODS: Sixty-six healthy adults (34 female; 33.6 ± 9.8 y; 24.6 ± 3.0 kg/m2) in a crossover trial were randomly assigned to 2-wk yogurt conditions in a counterbalanced order with ≥4-wk washout: 1) Honey (HON): yogurt plus honey and 2) Negative Control (NC): heat-treated yogurt plus sugar. Of the participants, n = 62 completed the trial, and n = 37 (17 female; 32.0 ± 8.3 y; 25.0 ± 2.9 kg/m2) elected to enroll in a third condition (a nonrandomized study extension) after ≥4-wk washout with a reference Positive Control (PC): yogurt plus sugar. At baseline and end of each of the 3 conditions, intestinal transit time was measured with dye capsules; probiotic abundance with fecal DNA 16S sequencing; digestive health with symptom/function records, Bristol stool consistency, Gastrointestinal Tolerability, and Gastrointestinal Quality of Life Index; mood with Positive and Negative Affect Schedule-Short Form, Depression Anxiety Stress Scales-42, Patient-Reported Outcomes Measurement Information System questionnaires, and an emotional image task; and cognition with a spatial reconstruction task. Data were analyzed using linear mixed-effects models (LMMs) with significance at P ≤ 0.05. Baseline and end data were included in the LMM, with fixed effects being treatment, time, treatment by time interaction, and baseline covariate, and the random effect being the participant. RESULTS: B. animalis was enriched in HON (d = 3.54; P = 0.0002) compared to controls with linear discriminant analysis effect size. Intestinal transit time, gastrointestinal health, mood, and cognition did not differ between conditions (LMM: Ps > 0.05). CONCLUSIONS: Yogurt + honey enriched B. animalis but did not reduce intestinal transit time or have other functional gastrointestinal, mood, or cognitive effects in adults. This trial was registered at www. CLINICALTRIALS: gov as NCT04187950 and NCT04901390.

The Evolution of Science and Regulation of Dietary Supplements: Past, Present, and Future.

Dietary supplement use in the United States is widespread and increasing, especially among certain population groups, such as older Americans. The science surrounding dietary supplements has evolved substantially over the last few decades since their formal regulation in 1994. Much has been learned about the mechanisms of action of many dietary supplement ingredients, but the evidence on their health effects is still building. As is true of much nutrition research, there are many studies that point to health effects, but not all are at the level of scientific evidence (e.g., randomized controlled interventions), rigor, or quality needed for definitive statements of efficacy regarding clinical end points. New technologies and approaches are being applied to the science of dietary supplements, including nutrigenomics and microbiome analysis, data science, artificial intelligence (AI), and machine learning-all of which can elevate the science behind dietary supplements. Products can contain an array of bioactive compounds derived from foods as well as from medicinal plants, which creates enormous challenges in data collection and management. Clinical applications, particularly those aimed at providing personalized nutrition options for patients, have become more sophisticated as dietary supplements are incorporated increasingly into clinical practice and self-care. The goals of this article are to provide historical context for the regulation and science of dietary supplements, identify research resources, and suggest some future directions for science in this field.

Skin and macular carotenoids and relations to academic achievement among school-aged children.

ABSTRACTObjectives: Carotenoids are plant pigments that accumulate in human tissue (e.g. macula and skin) and can serve as biomarkers for diet quality; however, knowledge on skin and macular carotenoids in relation to cognition in children is limited. This study aimed to address this gap by assessing links between skin and macular carotenoids and academic achievement in school-aged children.Methods: Children 7-12 years old (n = 81) participated in a crosssectional study. Skin and macular carotenoids were measured with reflection spectroscopy and heterochromatic flicker photometry, respectively. Academic achievement was measured using Woodcock-Johnson IV (WJ-IV). Body Mass Index was calculated using height and weight measurements, demographic information was collected using a family demographics and pediatric health history questionnaire, and carotenoid intake was assessed using 7-day diet records.Results: Skin carotenoids were not related to macular pigment (r = 0.08, p = 0.22). Adjusting for age, sex, BMI percentile, household income, and total carotenoid consumption (mg/1000kcal), skin carotenoids were predictive of math (ß = 0.27, p = 0.02), broad math (ß = 0.36, p < 0.01) and math calculation (ß = 0.38, p < 0.01). Skin carotenoids displayed trending relationships with broad reading (ß = 0.23, p = 0.05) and reading fluency (ß = 0.22, p = 0.07). There were no significant associations between macular pigment and academic achievement (all ß's ≤ 0.07, all p's ≥ 0.56).Discussion: Skin carotenoids were positively associated with academic abilities in children, while macular carotenoids did not display this relationship. Future interventions examining prospective effects of changes in carotenoids in different tissues on childhood academic achievement are warranted.

Dietary fiber intake and fecal short-chain fatty acid concentrations are associated with lower plasma lipopolysaccharide-binding protein and inflammation.

Consuming adequate dietary fiber is a promising strategy for reducing systemic inflammation. The objective was to evaluate relationships between dietary fiber intake, markers of metabolic endotoxemia, and systemic inflammation in adults. This was a cross-sectional study of 129 healthy participants (age 33.6 ± 6.1 yr, BMI 30.5 ± 6.9 kg/m2). Dietary fiber intake was assessed by food frequency questionnaire. Adiposity was measured using dual-energy X-ray absorptiometry (DXA). Fecal short-chain fatty acids (SCFA) were quantified using gas chromatography-mass spectrometry. Fecal microbiota sequence data (V4 region, 16S rRNA gene) were analyzed using DADA2 and QIIME2. Inflammatory cytokines were assessed with enzyme-linked immunosorbent assays; flow cytometry was conducted for monocyte surface marker quantification. Bivariate correlations and generalized step-wise linear modeling were used for statistical analyses. Plasma C-reactive protein (CRP) and interleukin (IL)-6 concentrations were positively related to whole body (CRP r = 0.45, P = <0.0001; IL-6 r = 0.34, P = 0.0002) and visceral adiposity (CRP r = 0.33, P = 0.0003; IL-6 r = 0.38, P = 0.0002). Plasma lipopolysaccharide-binding protein (LBP) concentrations were inversely related to dietary fiber intake (r = -0.22, P = 0.03) and fecal SCFA (acetate r = -0.25, P = 0.01; propionate r = -0.28, P = 0.003; butyrate r = -0.23, P = 0.02). Whole body adiposity, dietary fiber, and fecal SCFA were the most predictive of plasma LBS-BP concentrations. Novel findings included associations between dietary fiber intake, the gastrointestinal microbiota, and systemic inflammation.NEW & NOTEWORTHY Dietary fiber intake may reduce the inflammation associated with obesity and metabolic disease. Our cross-sectional analysis revealed that dietary fiber intake and fecal short-chain fatty acids are inversely associated with lipopolysaccharide-binding protein, a marker of systemic inflammation. In addition, plasma interleukin-6 and C-reactive protein were positively related to markers of adiposity.

Diet Quality and the Fecal Microbiota in Adults in the American Gut Project.

BACKGROUND: The Dietary Guidelines for Americans advises on dietary intake to meet nutritional needs, promote health, and prevent diseases. Diet affects the intestinal microbiota and is increasingly linked to health. It is vital to investigate the relationships between diet quality and the microbiota to better understand the impact of nutrition on human health. OBJECTIVES: This study aimed to investigate the differences in fecal microbiota composition in adults from the American Gut Project based on their adherence to the Dietary Guidelines for Americans. METHODS: This study was a cross-sectional analysis of the 16S sequencing and food frequency data of a subset of adults (n = 432; age = 18-60 y; 65% female, 89% white) participating in the crowdsourced American Gut Project. The Healthy Eating Index-2015 assessed the compliance with Dietary Guideline recommendations. The cohort was divided into tertiles based on Healthy Eating Index-2015 scores, and differences in taxonomic abundances and diversity were compared between high and low scorers. RESULTS: The mean Total Score for low-scoring adults (58.1 ± 5.4) was comparable with the reported score of the average American adult (56.7). High scorers for the Total Score and components related to vegetables, grains, and dairy had greater alpha diversity than low scorers. High scorers in the fatty acid component had a lower alpha diversity than low scorers (95% CI: 0.35, 1.85). A positive log-fold difference in abundance of plant carbohydrate-metabolizing taxa in the families Lachnospiraceae and Ruminococcaceae was observed in high-scoring tertiles for Total Score, vegetable, fruit, and grain components (Benjamini-Hochberg; q < 0.05). CONCLUSIONS: Adults with greater compliance to the Dietary Guidelines demonstrated higher diversity in their fecal microbiota and greater abundance of bacteria capable of metabolizing complex carbohydrates, providing evidence on how Dietary Guidelines support the gut microbiota.

Prebiotic Consumption Alters Microbiota but Not Biological Markers of Stress and Inflammation or Mental Health Symptoms in Healthy Adults: A Randomized, Controlled, Crossover Trial.

BACKGROUND: Chronic stress contributes to systemic inflammation and diminished mental health. Although animal work suggests strong links with the microbiota-gut-brain axis, clinical trials investigating the effectiveness of prebiotics in improving mental health and reducing inflammation are lacking. OBJECTIVES: We aimed to determine fructooligosaccharide (FOS) and galactooligosaccharide (GOS) effects on biological markers of stress and inflammation and mental health symptoms in adults. Secondary outcomes included fecal microbiota and metabolites, digestive function, emotion, and sleep. METHODS: Twenty-four healthy adults (25-45 y; 14 females, 10 males; BMI, 29.3 ± 1.8 kg/m2) from central Illinois participated in a 2-period, randomized, controlled, single-blinded crossover trial. Interventions included the prebiotic (PRE) treatment (237 mL/d Lactaid low-fat 1% milk, 5 g/d FOS, 5 g/d GOS) and control (CON) (237 mL/d Lactaid), which were consumed in counterbalanced order for 4 wk each, separated by ≥4-wk washout. Inflammatory markers were measured in blood plasma (>10-h fast) and cortisol in urine. The Depression Anxiety Stress Scales-42 assessed mental health symptoms. Fecal samples were collected for 16S rRNA gene (V4 region) sequencing and analysis. Emotion was measured by rating images from a computer task. Sleep was assessed using 7-d records and accelerometers. Change scores were analyzed using linear mixed models with treatment and baseline covariate as fixed effects and participant ID as the random effect. RESULTS: There were no differences in change scores between PRE and CON treatments on biological markers of stress and inflammation or mental health. PRE increased change in percent sequences (q = 0.01) of Actinobacteriota (CON: 0.46 ± 0.70%; PRE: 5.40 ± 1.67%) and Bifidobacterium (CON: -1.72 ± 0.43%; PRE: 4.92 ± 1.53%). There were also no differences in change scores between treatments for microbial metabolites, digestive function, emotion, or sleep quality. CONCLUSIONS: FOS+GOS did not affect biological markers of stress and inflammation or mental health symptoms in healthy adults; however, it increased Bifidobacterium. CLINICAL TRIAL REGISTRY: NCT04551937, www. CLINICALTRIALS: gov.

Fecal Metabolites as Biomarkers for Predicting Food Intake by Healthy Adults.

BACKGROUND: The fecal metabolome is affected by diet and includes metabolites generated by human and microbial metabolism. Advances in -omics technologies and analytic approaches have allowed researchers to identify metabolites and better utilize large data sets to generate usable information. One promising aspect of these advancements is the ability to determine objective biomarkers of food intake. OBJECTIVES: We aimed to utilize a multivariate, machine learning approach to identify metabolite biomarkers that accurately predict food intake. METHODS: Data were aggregated from 5 controlled feeding studies in adults that tested the impact of specific foods (almonds, avocados, broccoli, walnuts, barley, and oats) on the gastrointestinal microbiota. Fecal samples underwent GC-MS metabolomic analysis; 344 metabolites were detected in preintervention samples, whereas 307 metabolites were detected postintervention. After removing metabolites that were only detected in either pre- or postintervention and those undetectable in ≥80% of samples in all study groups, changes in 96 metabolites relative concentrations (treatment postintervention minus preintervention) were utilized in random forest models to 1) examine the relation between food consumption and fecal metabolome changes and 2) rank the fecal metabolites by their predictive power (i.e., feature importance score). RESULTS: Using the change in relative concentration of 96 fecal metabolites, 6 single-food random forest models for almond, avocado, broccoli, walnuts, whole-grain barley, and whole-grain oats revealed prediction accuracies between 47% and 89%. When comparing foods with one another, almond intake was differentiated from walnut intake with 91% classification accuracy. CONCLUSIONS: Our findings reveal promise in utilizing fecal metabolites as objective complements to certain self-reported food intake estimates. Future research on other foods at different doses and dietary patterns is needed to identify biomarkers that can be applied in feeding study compliance and clinical settings.

MIND Dietary Pattern Adherence Is Selectively Associated with Cognitive Processing Speed in Middle-Aged Adults.

BACKGROUND: Most previous work has focused on a single-nutrient, bottom-up approach when examining the influence of diet on neurocognition. Thus, the impact of dietary patterns on cognitive health is underinvestigated. OBJECTIVES: We aimed to investigate the relation between different diet indices [i.e., Mediterranean, Dietary Approaches to Stop Hypertension (DASH), Healthy Eating Index-2015 (HEI-2015), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND)] and attentional inhibition and neuroelectric function. METHODS: We undertook a cross-sectional analysis of adults aged 34.1 ± 6.0 y (n = 207, 116 females) with a BMI of 18.5 to >40 kg/m2 who completed the Dietary History Questionnaire II (DHQII) FFQ (Past Month and Year with Serving Sizes) to assess adherence to different diet quality indices. Attentional inhibition was assessed using a modified Eriksen flanker task during which event-related potentials (ERPs) were recorded. The amplitude and latency of the P3/P300 ERP were used to index attentional resource allocation and information processing speed, respectively. RESULTS: P3 peak latency was inversely associated with greater adherence to the MIND dietary pattern during incongruent flanker trials (∆R2 = 0.02, ß = -0.14, P = 0.043) but not during congruent trials. Adherence to the Mediterranean, DASH, and HEI-2015 patterns was not associated with P3 latency (P > 0.05). No associations were observed between the diet indices and attentional inhibition at the behavioral level (i.e., accuracy or reaction time) or P3 amplitude (all P values >0.05). CONCLUSIONS: Greater adherence to the MIND diet was selectively associated with faster information processing speed in middle-aged adults with healthy to obese BMI. Further, the influence of the MIND diet for faster information processing speed might be particularly beneficial when cognitive control demands are increased. Future intervention trials testing the effects of consuming a MIND diet on cognitive function are warranted to help inform dietary recommendations for healthy cognitive aging.

Macular Pigment Optical Density and Skin Carotenoids in a Childhood Sample.

BACKGROUND: Carotenoids are plant pigments with light filtering and antioxidant properties that deposit in human tissues, including retina and skin. Descriptive characteristics and covariates of carotenoid status in macula and skin have been examined in adults; however, similar studies in children are limited. Thus, this study aimed to delineate how factors of age, sex, race, weight status, and dietary carotenoid intake relate to macular and skin carotenoids in children. METHODS: Children (7-13 y, N = 375) completed heterochromatic flicker photometry to assess macular pigment optical density (MPOD). Participants underwent anthropometrics to measure weight status (BMI percentile [BMI%]), and parent/guardian provided demographic information. Subsample data were available for skin carotenoids (N = 181), assessed using reflection spectroscopy, and dietary carotenoids (N = 101) using the Block Food Frequency Questionnaire. Relationships between skin and macular carotenoids were assessed using partial Pearson's correlations controlling for age, sex, race, and BMI%. Relationships between dietary carotenoids and macular and skin carotenoids were assessed using stepwise linear regression including age, sex, race, and BMI% in the model. RESULTS: Mean MPOD was 0.56 ± 0.22 and skin carotenoid score was 282 ± 94.6. There was no significant correlation between MPOD and skin carotenoids (r = 0.02, P = 0.76). BMI% was negatively associated with skin (stdß = -0.42, P < 0.001), but not macular carotenoids (stdß = -0.04, P = 0.70). Neither MPOD nor skin carotenoids were associated with age, sex, or race (all P > 0.10). MPOD was positively associated with energy-adjusted reported lutein + zeaxanthin intake (stdß = 0.27, P = 0.01). Skin carotenoids were positively associated with energy-adjusted reported carotenoid intake (stdß = 0.26, P = 0.01). CONCLUSIONS: The mean MPOD values in children were higher than what has been reported in adult populations. Previous studies in adult samples report an average MPOD of 0.21. Although macular and skin carotenoids were not related, they were associated with dietary carotenoids relevant to the respective tissues; however, skin carotenoids may be more susceptible negative influence from higher weight status.

Consumption of a fermented dairy beverage improves hippocampal-dependent relational memory in a randomized, controlled cross-over trial.

Objectives: We aimed to determine whether consumption of a fermented dairy beverage containing probiotic microorganisms influences negative mood states, stress, and hippocampal memory performance in healthy adults. Methods: Adults (25-45 yrs, N = 26) free of gastrointestinal and mental illness were enrolled in a single-blind, randomized, controlled, crossover trial. Participants completed testing prior to and after 4-week consumption, with a 2-4 week washout between treatments of: (1) 8 oz of a dairy-based fermented beverage containing 25-30 billion colony forming units of live and active kefir cultures or (2) 8 oz isocaloric, non-fermented, 1% low-fat lactose-free dairy-based control beverage. Hippocampal-dependent relational memory was assessed using a spatial reconstruction task. Negative mood states of depression and anxiety were assessed using the Depression Anxiety Stress Scales-42 (DASS-42). Pooled 24-hour urine samples were analyzed using an enzyme-linked immunosorbent assay to determine urinary free-cortisol (UFC) concentrations. Fecal microbiota composition was assessed using 16S rRNA gene sequencing. Results: Lactobacillus was increased by 235% following fermented dairy consumption compared to the control (p < .01). Furthermore, the fermented dairy beverage improved performance on two metrics of relational memory, misplacement (p = .04) and object-location binding (p = .03). UFC and DASS-42 scores (all p's > .08) were not significantly changed by either arm of the intervention. No correlations were observed between the change in Lactobacillus and memory performance. Conclusions: Fermented dairy consumption increased the presence of certain microorganisms in the gut and improved relational memory in healthy adults. However, the benefits observed for relational memory were not related to changes in Lactobacillus.Trial registration: ClinicalTrials.gov identifier: NCT02849275.

Dietary lutein plus zeaxanthin and choline intake is interactively associated with cognitive flexibility in middle-adulthood in adults with overweight and obesity.

BACKGROUND: The xanthophyll carotenoids lutein+zeaxanthin and the dietary component choline have been linked to benefits in cognition. However, knowledge on the interactive influence of these dietary components on cognitive function is sparse. DESIGN: 80 middle-aged adults with overweight and obesity (Body Mass Index: (BMI) ≥25.0 kg/m²), completed 7-day diet records, venous blood draws, heterochromatic flicker photometry, assessment of intelligence quotient (IQ), and a cognitive flexibility task while undergoing electroencephalographic recording for event-related potential (ERP) extraction. Multiplicative interaction terms and hierarchical linear regressions, controlling for age, BMI, sex, annual household income, and IQ were utilized to assess independent and interactive contributions of dietary and biomarker data on Switch task outcomes. RESULTS: Higher intake of lutein+zeaxanthin and choline was associated interactively, but not independently, with faster reaction time (RT), after controlling for pertinent covariates. Dietary intake of lutein+zeaxanthin and choline was associated with serum lutein concentrations, but not with plasma choline metabolites nor macular pigmentation. Plasma phosphatidylcholine (PC) concentrations were associated with higher accuracy in Switch trials, while no other biomarkers were associated with cognitive outcomes. Dietary intake and biomarker data were not related to the N2 nor P3 ERP component. CONCLUSIONS: Among a sample of adults with overweight and obesity, greater intake of choline and lutein+zeaxanthin was associated with faster performance on a cognitive flexibility task. Future work examining methods of increasing consumption of both of these dietary components as a possible means of improving or maintaining cognitive flexibility among adults with overweight and obesity is therefore warranted.

Higher protein intake during resistance training does not potentiate strength, but modulates gut microbiota, in middle-aged adults: a randomized control trial.

Protein intake above the recommended dietary allowance (RDA) and resistance training are known anabolic stimuli to support healthy aging. Specifically, protein supplementation after resistance exercise and nightly are strategies to maximize utilization of protein intake above the RDA in healthy adults. As such, the primary objective was to examine the efficacy of protein supplementation and nutritional counseling resulting in either moderate (MOD: ∼1.0 g·kg-1·day-1) or higher (HIGH: ∼1.6 g·kg-1·day-1) protein intake during resistance training on strength (one-repetition maximum, 1-RM; isokinetic and isometric peak torque) in healthy middle-aged adults. Exploratory analyses include diet-exercise effects on lean body mass (LBM), clinical biomarkers, gut microbiota, and diet composition. In all, 50 middle-aged adults (age: 50 ± 8 yr, BMI: 27.2 ± 4.1 kg/m2) were randomized to either MOD or HIGH protein intake during a 10-wk resistance training program (3 × wk). Participants received dietary counseling and consumed either 15 g (MOD) or 30 g (HIGH) of protein from lean beef in the immediate postexercise period and each evening. Maximal strength (1-RM) for all upper and lower body exercises significantly increased with no effect of protein intake (P < 0.050). There was a main effect of time for LBM (P < 0.005). Cardiovascular, renal, or glycemic biomarkers were not affected by the intervention. Gut microbiota were associated with several health outcomes (P < 0.050). In conclusion, higher protein intake above moderate amounts does not potentiate resistance training adaptations in previously untrained middle-aged adults. This trial was registered at clinicaltrials.gov as NCT03029975.NEW & NOTEWORTHY Our research evaluates the efficacy of higher in comparison with moderate animal-based protein intake on resistance exercise training-induced muscle strength, clinical biomarkers, and gut microbiota in middle-aged adults through a dietary counseling-controlled intervention. Higher protein intake did not potentiate training adaptations, nor did the intervention effect disease biomarkers. Both diet and exercise modified gut microbiota composition. Collectively, moderate amounts of high-quality, animal-based protein is sufficient to promote resistance exercise adaptations at the onset of aging.

The relationships between prolonged sedentary time, physical activity, cognitive control, and P3 in adults with overweight and obesity.

BACKGROUND/OBJECTIVES: To assess the relationships between daily sedentary time (ST), prolonged ST, moderate-to-vigorous physical activity (MVPA), and behavioral and neuroelectric indices of cognitive control in adults with overweight and obesity (OW/OB). SUBJECTS/METHODS: A cross-sectional design was used. Overall, 89 adults (BMI = 31.9 ± 4.9 kg/m2) provided measures of ST, prolonged ST (i.e., ST accumulated in ≥20 min), and MVPA from a hip-worn accelerometer worn over 7 days. Inhibitory control was measured with a modified Eriksen flanker task and cognitive flexibility with task switching. The amplitude and the latency of the P3 component of event-related potentials during each task were used as measures of attentional resource allocation and information processing speed, respectively. RESULTS: After adjusting for ST and MVPA, prolonged ST was related to greater interference (i.e., a larger decrement in accuracy between congruent and incongruent trials of the flanker task) indicative of a specific relationship between prolonged ST and poorer inhibitory control. Before adjusting for ST, MVPA was related to a smaller Global Switch Cost expressed as larger (more positive) amplitude of the P3 difference wave (mixed-task minus single-task condition of the switch task). Adjustment for ST attenuated this association to non-significance. CONCLUSIONS: Our findings suggest that future interventions focused on improving inhibitory control in adults with OW/OB should target restructuring ST in addition to current efforts to increase MVPA.

Fecal Bacteria as Biomarkers for Predicting Food Intake in Healthy Adults.

BACKGROUND: Diet affects the human gastrointestinal microbiota. Blood and urine samples have been used to determine nutritional biomarkers. However, there is a dearth of knowledge on the utility of fecal biomarkers, including microbes, as biomarkers of food intake. OBJECTIVES: This study aimed to identify a compact set of fecal microbial biomarkers of food intake with high predictive accuracy. METHODS: Data were aggregated from 5 controlled feeding studies in metabolically healthy adults (n = 285; 21-75 y; BMI 19-59 kg/m2; 340 data observations) that studied the impact of specific foods (almonds, avocados, broccoli, walnuts, and whole-grain barley and whole-grain oats) on the human gastrointestinal microbiota. Fecal DNA was sequenced using 16S ribosomal RNA gene sequencing. Marginal screening was performed on all species-level taxa to examine the differences between the 6 foods and their respective controls. The top 20 species were selected and pooled together to predict study food consumption using a random forest model and out-of-bag estimation. The number of taxa was further decreased based on variable importance scores to determine the most compact, yet accurate feature set. RESULTS: Using the change in relative abundance of the 22 taxa remaining after feature selection, the overall model classification accuracy of all 6 foods was 70%. Collapsing barley and oats into 1 grains category increased the model accuracy to 77% with 23 unique taxa. Overall model accuracy was 85% using 15 unique taxa when classifying almonds (76% accurate), avocados (88% accurate), walnuts (72% accurate), and whole grains (96% accurate). Additional statistical validation was conducted to confirm that the model was predictive of specific food intake and not the studies themselves. CONCLUSIONS: Food consumption by healthy adults can be predicted using fecal bacteria as biomarkers. The fecal microbiota may provide useful fidelity measures to ascertain nutrition study compliance.

Avocado Consumption Alters Gastrointestinal Bacteria Abundance and Microbial Metabolite Concentrations among Adults with Overweight or Obesity: A Randomized Controlled Trial.

BACKGROUND: Avocados are rich in dietary fiber and monounsaturated fatty acids (MUFAs), nutrients that have been independently connected to metabolic health benefits and the gastrointestinal microbiota. OBJECTIVES: We aimed to evaluate the impact of avocado consumption on the gastrointestinal microbiota and microbial metabolites, secondary outcomes of the Persea americana for Total Health (PATH) study, and conduct exploratory analyses to assess relations between the fecal microbiota, fecal metabolites, and health markers. METHODS: Adults [n = 163, 25-45 y, BMI (kg/m2) ≥ 25.0] were enrolled in the PATH study, a 12-wk investigator-blinded trial where participants were batch randomized to match the 2 groups by age, sex, visceral adiposity, and fasting glucose concentrations. Participants consumed isocaloric meals with or without avocado (175 g, men; 140 g, women) once daily for 12 wk. The fecal microbiota was assessed with 16S ribosomal RNA gene (V4 region) sequencing and analysis using DADA2 and QIIME2. Fecal fatty acid and bile acid concentrations were quantified using GC and LC-MS. Per-protocol (≥80% meal consumption) and intent-to-treat analyses were conducted using univariate ANOVA and Mann-Whitney U tests. Bivariate correlations were conducted between fecal microbiota, fecal metabolites, and health measures. RESULTS: The avocado treatment increased ɑ diversity and enriched Faecalibacterium, Lachnospira, and Alistipes between 26% and 65% compared with the control group. The avocado group had 18% greater fecal acetate, 70% greater stearic acid, and 98% greater palmitic acid concentrations than the control group, while the concentrations of the bile acids cholic and chenodeoxycholic acid were 91% and 57% lower, respectively. CONCLUSIONS: Daily avocado consumption resulted in lower fecal bile acid concentrations, greater fecal fatty acid and SCFAs, and greater relative abundances of bacteria capable of fiber fermentation, providing evidence that this nutrient-dense food affects digestive physiology, as well as the composition and metabolic functions of the intestinal microbiota. This trial was registered at www.clinicaltrials.gov as NCT02740439.

Avocado Consumption, Abdominal Adiposity, and Oral Glucose Tolerance Among Persons with Overweight and Obesity.

BACKGROUND: Although intake of Hass avocado has been cross-sectionally linked to lower abdominal obesity, knowledge of the effects of avocado consumption on abdominal adiposity and glycemic outcomes remains limited. OBJECTIVE: The effects of avocado consumption on abdominal adiposity, insulin resistance, oral-glucose-tolerance test (OGTT), and estimated ß-cell function were evaluated. METHODS: A total of 105 adults aged 25-45 y (61% female) with BMI ≥25 kg/m2 were randomly assigned to an intervention (N = 53) that received a daily meal with 1 fresh Hass avocado or a control (N = 52) that received an isocaloric meal with similar ingredients without avocado for 12 wk. DXA was used to assess the primary outcomes of abdominal adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT (VS Ratio)]. Fasted glucose and insulin were used to assess the primary outcomes of insulin resistance (HOMA-IR), and insulin sensitivity (Matsuda index) and ß-cell function (Insulinogenic index) were estimated using an OGTT. Changes between groups were compared using an ANCOVA. Secondary analyses were conducted based on sex. RESULTS: The control group exhibited a greater reduction in SAAT [-54.5 ± 155.8 g (control) compared with 17.4 ± 155.1 g (treatment), P = 0.017] and increase in VS Ratio [0.007 ± 0.047 (control) compared with -0.011 ± 0.044 (treatment), P = 0.024]. Among females, the treatment group exhibited a greater reduction in VAT [1.6 ± 89.8 g (control) compared with -32.9 ± 81.6 g (treatment), P = 0.021] and VS Ratio [0.01 ± 0.05 (control) compared with -0.01 ± 0.03 (treatment), P = 0.001]. Among males, there was no significant difference between groups in changes in abdominal adiposity or glycemic outcomes. CONCLUSIONS: Daily consumption of 1 fresh Hass avocado changed abdominal adiposity distribution among females but did not facilitate improvements in peripheral insulin sensitivity or ß-cell function among adults with overweight and obesity.This study was registered at clinicaltrials.gov as NCT02740439.

Dietary choline is related to neural efficiency during a selective attention task among middle-aged adults with overweight and obesity.

Objectives: Obesity is associated with poorer brain health and cognitive function. However, it is not clear whether specific dietary factors may provide neuroprotective effects among individuals with overweight and obesity. The aim of this study was to examine the impact of choline intake on neurophysiological markers of attentional control among young and middle-aged adults with overweight or obesity.Methods: 146 adults with BMI ≥25 kg/m2 (34.0 ± 5.9 years, 57 males) participated in the study. Behavioral performance (accuracy and reaction time) and neuroelectric indices (event-related brain potentials [ERPs]) of attentional inhibition were assessed during a Flanker task. Specifically, the amplitude and latency of the P3 waveform in a central-parietal region of interest (ROI) were used to index attentional resource allocation and information processing speed, respectively. Choline intake and overall diet quality (Healthy Eating Index [HEI-2015]) were assessed using 7-day diet records. Intelligence Quotient was assessed using the Kaufman-Brief Intelligence Test. Regression analyses were conducted to examine the relationship between habitual dietary choline intake and cognitive outcomes following adjustment of demographic factors, IQ, HEI-2015, and BMI.Results: Choline intake was selectively associated with a lower peak amplitude of the P300 waveform during incongruent trials (ß = -0.25, p = <0.01). No significant relationships were observed for accuracy or reaction time.Discussion: Higher choline intake is associated with more efficient neural processing among adults with overweight and obesity. Intervention are necessary to determine whether choline consumption provides neuroprotective effects for executive function among individuals with elevated weight status.

Hydration Biomarkers Are Related to the Differential Abundance of Fecal Microbiota and Plasma Lipopolysaccharide-Binding Protein in Adults.

INTRODUCTION: Prevalence of chronic hypohydration remains elevated among adults in the USA; however, the health effects of hypohydration in regards to human gut health have not been explored. METHODS: This study examined the relationship between total water intake, hydration biomarkers (first-morning urine specific gravity [FMUsg], first-morning urine volume [FMUvol], and plasma copeptin), fecal microbiota, and plasma lipopolysaccharide-binding protein (LBP) in adults (25-45 years, 64% female). Fecal microbiota composition was assessed using 16S rRNA gene sequencing (V4 region). Immunoassays quantified plasma copeptin and LBP in fasted venous blood samples. Dietary variables were measured using 7-day food records. Linear discriminant analysis effect size (LEfSe) analyzed differentially abundant microbiota based on median cutoffs for hydration markers. Multiple linear regressions examined the relationship between LBP and copeptin. RESULTS: LEfSe identified 6 common taxa at the genus or species level that were differentially abundant in FMUsg, total water (g/day), or plasma copeptin (µg/mL) groups when split by their median values. Uncultured species in the Bacteroides, Desulfovibrio, Roseburia, Peptococcus, and Akkermansia genera were more abundant in groups that might indicate poorer hydration status. Multivariate linear analyses revealed a positive relationship between plasma copeptin and LBP when controlling confounding variables (F(6,52) = 4.45, p = 0.002, R2 = 0.34). CONCLUSIONS: Taxa common between markers are associated with the intestinal mucus layer, which suggests a potential link between hydration status and intestinal mucus homeostasis. The relationship between LBP and copeptin indicates that copeptin may be sensitive to metabolic endotoxemia and potentially gut barrier function.