Search Results (440)

This narrative review examines the effects of caffeine on brain health in older adults, with particular attention to its potential for dependence—an often-overlooked issue in geriatric care. Caffeine acts on central adenosine, dopamine, and glutamate systems, producing both stimulating and rewarding effects that can foster tolerance and habitual use. Age-related pharmacokinetic and pharmacodynamic changes prolong caffeine’s half-life and increase physiological sensitivity in the elderly. While moderate consumption may enhance alertness, attention, and possibly offer neuroprotective effects—especially in Parkinson’s disease and Lewy body dementia—excessive or prolonged use may lead to anxiety, sleep disturbances, and cognitive or motor impairment. Chronic exposure induces neuroadaptive changes, such as adenosine receptor down-regulation, resulting in tolerance and withdrawal symptoms, including headache, irritability, and fatigue. These symptoms, often mistaken for typical aging complaints, may reflect a substance use disorder yet remain under-recognized due to caffeine’s cultural acceptance. The review explores caffeine’s mixed role in neurological disorders, being beneficial in some and potentially harmful in others, such as restless legs syndrome and frontotemporal dementia. Given the variability in individual responses and the underestimated risk of dependence, personalized caffeine intake guidelines are warranted. Future research should focus on the long-term cognitive effects and the clinical significance of caffeine use disorder in older populations. Full article

Background: Adolescence is characterized by physical and psychosocial changes. This implies modifying or implementing correct nutritional habits at an early age, which would have an impact on a healthy adult life. Objectives: The FFQ of dietary patterns has not been estimated in the population of adolescents. Therefore, conducting a pilot, cross-sectional, comparative, and correlational study, we sought to identify frequently consumed foods in an adolescent population. Methods: As part of the methodology, a Food Frequency Questionnaire (FFQ) was given to a non-probability convenience sample of 178 subjects aged 14 to 19 years to evaluate the most frequently consumed foods. Results: This study showed that the diet of Mexican adolescents was characterized with little variability in the foods consumed: 28.20% of the population had a good consumption of milk (1 to 5 serving/day), 16.50% of sugars, and 16% of cereals, while only less than 15% had a good consumption of source animal foods, fruits and vegetables, oils, and fat. Conclusions: Mexican adolescents have demonstrated that their diet is poorly varied. Adolescence is an important period in life that can define habitual dietary intake, and therefore, it is crucial to promote healthy eating at this age. Further research and appropriate public policies are needed. Full article

Background: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder characterized by reproductive and metabolic abnormality disorders. Dietary factors influence the body composition and hydration status, which may exacerbate PCOS symptoms. The aim of this study was to assess the associations between the habitual nutrient intake and bioelectrical impedance analysis parameters in Polish women with PCOS and healthy controls, in order to identify potential nutritional targets for a non-pharmacological intervention. Methods: This study involved 50 women aged 18–45 years (25 with PCOS and 25 healthy). Participants kept 7-day food diaries and their body composition was assessed using the SECA mBCA 515 analyzer. The nutrient intake was compared with EFSA recommendations. Results: Women with PCOS had a higher body weight, waist circumference and body mass index, visceral adipose tissue, and fat mass index, despite no difference in their total energy intake. They consumed more omega-3 fatty acids (EPA + DHA) than the control group. Vitamin D deficiency and irregular supplementation were common in both groups. Body composition parameters such as the phase angle and ECW/TBW ratio correlated with the diet quality—especially with protein; fiber; and vitamin B2, B12, and folate levels. Conclusions: The obtained results showed significant differences in body compositions and the presence of a relationship between the nutrient intake and bioimpedance parameters in women with PCOS. These results emphasize the importance of a comprehensive nutritional and body composition assessment in planning dietary interventions in this group of patients. Full article

Background/Objectives: Inter-individual metabolic responses to caffeine are shaped by CYP1A2 clearance rate and by concurrent lipid- or glucose-lowering drugs. We investigated how habitual caffeine intake relates to serum cholesterol and fasting glucose under different CYP1A2 rs762551 genotypes and statin or oral antidiabetic (OAD) use. Methods: A prospective cross-sectional analysis was performed on 358 adults (AA = 65, AC = 163, CC = 130) with recorded genotype, daily caffeine intake, total cholesterol, fasting glucose, and medication status. Multivariable linear regression tested the main and interaction effects of caffeine (mg day⁻¹), genotype, and therapy. Results: Caffeine intake was positively associated with cholesterol levels (β = 0.30; p < 0.001). A significant genotype × caffeine interaction (β = 0.27; p < 0.001) revealed the steepest rise in fast metabolisers (AA) not on statins, an effect largely blunted by statin therapy. For glucose, the genotype × caffeine term was also significant (β = 0.30; p < 0.001). Among slow metabolisers (CC) without OADs, caffeine correlated positively with glycaemia (r = 0.34; p = 0.028), whereas in fast metabolisers on OADs the association reversed (r = −0.36; p = 0.015). No meaningful associations occurred in AC carriers. Conclusions: Caffeine’s metabolic impact depends jointly on CYP1A2 genotype and medication. It raises cholesterol in fast metabolisers lacking statins and elevates glucose in slow metabolisers without OADs, yet may lower glucose when rapid metabolisation coincides with antidiabetic therapy. Accounting for this gene–diet–drug interplay could refine caffeine guidance within precision nutrition frameworks. Full article

Sweet sensing is a fundamental sensory experience that plays a critical role not only in food preference, reward and dietary behaviour but also in glucose metabolism. Sweet taste receptors (STRs), composed of a heterodimer of taste receptor type 1 member 2 (T1R2) and member 3 (T1R3), are now recognised as being widely distributed throughout the body, including the gastrointestinal tract. Preclinical studies suggest these receptors are central to nutrient and glucose sensing, detecting energy availability and triggering metabolic and behavioural responses to maintain energy balance. Both internal and external factors tightly regulate their signalling pathways, and dysfunction within these systems may contribute to the development of metabolic disorders such as obesity and type 2 diabetes (T2D). Functional magnetic resonance imaging (fMRI) has provided valuable insights into the neural mechanisms underlying sweet sensing by mapping brain responses to both lingual/oral and gastrointestinal sweet stimuli. This review highlights key findings from fMRI studies and explores how these neural responses are modulated by metabolic state and individual characteristics such as body mass index, habitual intake and metabolic health. By integrating current evidence, this review advances our understanding of the complex interplay between sweet sensing, brain responses, and health and identifies key gaps and directions for future research in nutritional neuroscience. Full article

Background/Objectives: Currently, Oman lacks a valid culture-specific food frequency questionnaire (FFQ) for adults. This research aimed to develop and validate a reliable (FFQ) specifically for Omani adults. The study was conducted in two phases, employing both qualitative and quantitative methods. Phase 1 was the development of the (FFQ); in this phase the Diet History Questionnaire II (DHQ II) was adapted to develop the Omani Food Frequency Questionnaire (OFFQ), translated to the Arabic language, back-translated to English, pilot tested, and then refined to be used in the reliability study. Phase 2 was the reliability study, in this phase, the OFFQ was administered twice in Arabic with the second being filled one to two weeks after the first questionnaire. Methods: A convenience sample of healthy Omani adults (n = 62) was recruited from Sultan Qaboos University (SQU) employees and students. To assess the reliability of the OFFQ both internal consistency and test–retest reliability were assessed. Internal consistency was assessed by conducting Cronbach’s α test, while test–retest reliability was assessed by comparing the median intake of food groups by calculating weighted kappa (K_W) and intraclass correlation coefficients (ICCs). Results: Weighted kappa (K_W) between the two OFFQ administrations showed fair to moderate agreement with (K_W) values ranging from 0.38 to 0.60 for questions assessing the frequency of intake. While the median (K_W) values between the two OFFQ administrations ranged from 0.26 to 0.58 for questions assessing portion size. The majority of food groups showed moderate to good test–retest reliability with median (ICCs) for food groups ranging from 0.57 to 0.80 for frequency questions and from 0.40 to 0.82 for portion questions. Conclusions: In conclusion, the newly developed OFFQ was deemed valid for the Omani dietary culture and is a reliable tool that can measure habitual dietary intake among Omani adults as evidenced by the reliability coefficients ranging from moderate to good agreement for the most food items and food groups. Future studies are warranted to assess the relative validity of the OFFQ and the inclusion of diverse demographic groups and a larger sample size. Full article

This review examines human digestive physiology and metabolic adaptations in the context of evolutionary dietary patterns, particularly those emphasizing carnivorous and scavenging behaviors. By integrating metabolomic data with archaeological, anatomical, and microbiological evidence, the study explores how early hominins adapted to intermittent but energy-dense animal-based diets. The analysis highlights the development of hepatic insulin resistance, enhanced fat and protein metabolism, and shifts in gut microbiota diversity as physiological signatures of meat consumption. Comparative evaluations of digestive enzyme profiles, intestinal morphology, and salivary composition underscore humans’ omnivorous flexibility and partial carnivorous specialization. Additionally, biomarkers such as ketone bodies, branched-chain amino acids, and trimethylamine-N-oxide are identified as metabolic indicators of habitual meat intake. These adaptations, though once evolutionarily advantageous, are discussed in relation to current metabolic disorders in modern nutritional contexts. Overall, this review presents a metabolomic framework for understanding the evolutionary trajectory of human digestion and its implications for health and dietary recommendations. Full article

Background: Chronic non-communicable diseases (NCDs) are a major global health challenge, with unhealthy diets contributing significantly to their burden. Metabolomics data offer new possibilities for identifying nutritional biomarkers, as demonstrated in short-term intervention studies. This study investigated associations between habitual dietary intake and urinary metabolites, a not well-studied area. Methods: Data were available from 496 participants of the population-based MEIA study. Linear and median regression models examined associations between habitual dietary intake and metabolites, adjusted for possible confounders. K-means clustering identified urinary metabolite clusters, and multinomial regression models were applied to analyze associations between food intake and metabolite clusters. Results: Using linear regression models, previously reported associations could be replicated, including citrus intake with proline betaine, protein intake with urea, and fiber intake with hippurate. Novel findings include positive associations of poultry intake with taurine, indoxyl sulfate, 1-methylnicotinamide, and trimethylamine-N-oxide. Milk substitutes were positively associated with urinary uracil, pseudouridine, 4-hydroxyhippurate, and 3-hydroxyhippurate, and inversely associated with quinic acid. Dietary fiber intake showed a positive association with 3-(3-hydroxyphenyl)-3-hydroxypropionic acid and a negative association with indoxyl sulfate. We identified sucrose and taurine as key metabolites differentiating metabolite clusters. Multinomial regression analysis confirmed significantly different dietary associations across clusters, particularly for fruits, processed meat, poultry, and alcoholic beverages. Conclusions: This study highlights established and novel food–metabolite associations, demonstrating the potential of urinary metabolomics for use as nutritional biomarkers in individuals from the general population. Full article

The EAT-Lancet diet is an outstanding model of a healthy, environmentally sustainable diet. However, its effects on the gut microbiota remain poorly explored. This study assessed the asso-ciation between adherence to the EAT-Lancet diet in habitual intake and the relative abundance of selected gut bacteria in a Mexican subpopulation. Fifty-four young adults (18–35 years) completed a validated Food Frequency Questionnaire (FFQ) and were nutritionally assessed. Participants were grouped into low, moderate, and high adherence levels to the EAT-Lancet diet. Blood samples were analysed for glucose and lipid profiles, and gDNA from faecal samples was analysed using Real-time qPCR to quantify gut bacteria. While no significant differences in bacterial abundance were observed across adherence levels, correlations emerged with increased adherence. Notably, Bifidobacterium negatively correlated with beef and lamb intake (rho −0.5, p < 0.05), and Akkermansia muciniphila negatively correlated with fish intake (rho −0.8, p < 0.05). Bilophila wadsworthia positively correlated with triglycerides, while Prevotella copri and Faecalibacterium prausnitzii negatively correlated with body fat and blood pressure, respectively. In addition, a non-significant trend toward a higher abundance of Firmicutes, Akkermansia muciniphila, and Prevotella copri was observed in the high-adherence group, whereas Lactobacillus tended to be more abundant in participants with low and moderate adherence. These findings suggest that adherence to the EAT-Lancet diet modulates gut microbiota composition. However, further controlled interventional studies are needed to confirm these effects and their implications for human health. Full article

Background/Objectives: Despite extensive research on caffeine’s (CAF’s) ergogenic effects, evidence regarding its impact on anaerobic performance in female athletes remains limited and inconclusive. The aim of this study was to investigate the acute effects of 6 mg/kg⁻¹ caffeine on anaerobic performance, functional strength, agility, and ball speed in female soccer players. Methods: A randomized, double-blind, placebo-controlled crossover design was employed. Thirteen moderately trained female soccer players (age: 21.08 ± 1.11 years; height: 161.69 ± 6.30 cm; weight: 59.69 ± 10.52 kg; body mass index (BMI): 22.77 ± 3.50 kg/m²; training age: 7.77 ± 1.16 years; habitual caffeine intake: 319 ± 160 mg/day) completed two experimental trials (caffeine vs. placebo (PLA)), separated by at least 48 h. Testing sessions included performance assessments in vertical jump (VJ), running-based anaerobic sprint test (RAST), bilateral leg strength (LS), handgrip strength (HS), single hop for distance (SH), medial rotation (90°) hop for distance (MRH), change of direction (COD), and ball speed. Rating of perceived exertion (RPE) was also recorded. Results: CAF ingestion significantly improved minimum (p = 0.011; d = 0.35) and average power (p = 0.007; d = 0.29) during RAST. A significant increase was also observed in SHR (single leg hop for distance right) performance (p = 0.045; d = 0.44). No significant differences were found in VJ, COD, ball speed, LS, HS, SHL, MRHR, or MRHL (p > 0.05). RPE showed a moderate effect size (d = 0.65) favoring the CAF condition, though not statistically significant (p = 0.110). Conclusions: In conclusion, acute CAF intake at a dose of 6 mg/kg⁻¹ may enhance anaerobic capacity and lower-limb functional strength in female soccer players, with no significant effects on jump height, agility, or upper-body strength. Full article

Objective: Eggs are a valuable source of nutrients and bioactive compounds that may influence the gastrointestinal tract by modulating the microbiome, promoting the production of gastrointestinal-related metabolites, and mediating inflammation. Limited human studies have explored the effects of whole egg intake on indices of gastrointestinal health. This systematic literature review aimed to synthesise research investigating the impact of whole egg consumption on markers of gastrointestinal health. Methods: Five databases were searched from inception until July 2024. Studies were included if they examined the link between whole egg consumption and gastrointestinal markers, including symptoms, gut microbiome composition, inflammation, colonic fermentation, and egg-derived metabolites such as trimethylamine N-oxide (TMAO) in healthy adults. Two reviewers independently conducted title and abstract and full-text screening, with conflicts resolved by a third reviewer. Similarly, two authors conducted data extraction, which was verified by a third. A risk of bias assessment was conducted using validated tools. Random effects meta-analyses were performed to summarise the effect of egg consumption on TMAO, choline, and C-reactive protein (CRP). Results: Twenty-two studies were included in a narrative synthesis and ten in the meta-analyses. Nine were randomised controlled trials (RCTs), three were non-randomised intervention trials, eight were cross-sectional, and two were prospective cohort studies. Meta-analyses indicated that egg consumption did not impact plasma TMAO (n = 6, p = 0.22) or CRP (n = 3, p = 0.45) concentrations but did increase plasma choline (n = 5, p < 0.001) in the short term (≤4 weeks). Four studies found correlations between habitual egg consumption and specific gut bacteria, although results varied as egg consumption was both positively and negatively associated with butyrate-producing genera. Conclusions: This review found conflicting results regarding egg consumption and most gastrointestinal outcomes, highlighting that future studies are needed to explore links between habitual egg intake and plasma TMAO, microbial diversity, and inflammation (PROSPERO registration: 408532). Full article

Background/Objectives: Brown seaweeds, such as Himanthalia elongata, are a promising source of dietary fiber. However, in vivo evidence regarding the effects of H. elongata intake on the human gut microbiota remains limited. This study aimed to evaluate the impact of daily H. elongata consumption on the gut microbiota composition and short-chain fatty acid production in overweight adults. Methods: A randomized, double-blind, placebo-controlled trial was conducted in which 10 overweight adult participants consumed 2 g/day of whole H. elongata for 30 days. Fecal samples were collected before and after the intervention for 16S rRNA sequencing and short-chain fatty acid analysis. Dietary intake was evaluated using a 24 h recall and a 3-day dietary record. Nutritional assessment was performed to determine habitual macronutrient consumption. Results: Baseline dietary analysis revealed an imbalanced macronutrient profile characterized by high intakes of total and saturated fats and protein, along with low carbohydrate and fiber consumption. In addition, 50% of the participants were obese, and 50% were overweight based on the BMI. Notable changes in the gut microbiota composition were observed after the intervention, including increases in short-chain fatty acid-producing species, such as Parabacteroides distasonis, Bacteroides eggerthii, Bacteroides uniformis, and Bacteroides obeum. Conclusions: This study provides the first clinical evidence in humans that whole H. elongata can beneficially modulate the gut microbiota composition. These results support the potential use of this seaweed as a functional prebiotic ingredient in dietary strategies aimed at enhancing gut health. Full article

Palmitic acid (PA) and oleic acid (OA) are, respectively, the most prevalent saturated and monounsaturated fatty acids (SFAs, MUFAs) in the human diet. The objective of this brief review is to explore how this ratio affects brain function. In two double-masked crossover trials in young adults, physical activity was greater and systemic inflammatory tone was diminished under a diet with a lower dietary PA/OA ratio compared to that of the typical North American Diet, and anger and total mood disturbance were diminished under the low- compared to the higher-PA/OA diet. In another diet trial in young women, functional magnetic resonance imaging showed that lowering the dietary PA/OA ratio decreased brain activation in regions of the basal ganglia, suggesting that brain function was reversibly altered by the dietary PA/OA ratio. Recently, a crossover trial in older adults showed that a lower dietary PA/OA ratio decreased systemic inflammatory tone and caused the greater activation of a working memory network. As people age, there are declines in cognition that impact functional abilities and independence, but the preservation of structural aspects of the brain in normal aging implies that there is the possibility of slowing, stopping, or reversing cognitive changes that impact daily life. Reducing pro-inflammatory cytokine secretion by lowering habitual PA intake for even brief periods of time may be one modality to improve cognitive function in older adults, not only in those with typical cognitive aging but in those with dementia as well. Full article

In this study, we aimed to investigate the occurrence of rare earth elements (REEs) in commonly consumed foods and assess the dietary exposure risks among different age groups in Zhejiang Province. The results showed that tea and shrimp had the highest REE detection rates, reaching 100%. Of all the food categories examined, tea exhibited the highest REE concentrations, significantly exceeding those in other foods. This may be attributed to differences in moisture content, root absorption mechanisms, and processing methods. The concentration pattern of REEs in all samples occurred in the following order: cerium > lanthanum > yttrium > neodymium > neodymium > scandium > praseodymium > gadolinium > dysprosium. The light REEs/heavy REEs (HREEs) ratio was consistently > 2 but remained lower than the ratios observed in the soil and sediments, indicating a potential risk of HREE enrichment. Dietary exposure assessments revealed that the total REE intake among Zhejiang residents was below the established safety threshold (51.3 µg/kg BW/day), with children experiencing the highest exposure (3.71 µg/kg BW/day), primarily due to their lower body weight. In the assessment of individual rare earth elements, Ce exposure in children aged ≤ 6 years exceeded the toxicological reference value. However, this threshold was established based on studies in pregnant and lactating populations and might not be directly applicable to young children. Therefore, overall dietary exposure to individual REEs remains within safe limits. REE exposure from tea consumption did not pose a health risk, even for habitual tea drinkers. These findings underscore the importance of continuous monitoring of REE accumulation in food and additional research on the potential long-term health effects, even though the current exposure levels of REEs are below the established safety limit. This is especially important considering the bioaccumulative nature of REEs and the limited paucity of toxicological data, particularly in vulnerable populations. Full article

The aim of the present study was to evaluate the effect of grazing the low deciduous forest (LDF) vegetation on the diversity of the rumen microbiome in growing lambs and its relationship with volatile fatty acid (VFA) profiles. After a 35-day indoor acclimatization (stabilization period), the lambs were assigned to two groups: housed (CG, n = 4) and grazing (EG, n = 4). The grazing lambs had a 14-day habituation period in the LDF (4 h/day) and a further 30 grazing days when fodder intake was observed. Ruminal samples were collected at the end of the stabilization, on day 14 post-stabilization (14DPS), and on day 44 post-stabilization (44DPS). The ruminal butyrate concentration showed a progressive decrease of approximately 23% over the time (p = 0.0130). The qualitative composition (p = 0.001) and relative proportions of bacteria (p = 0.004) in EG-44DPS exhibited a greater diversity, with 107 total genera and 19 unique, significant abundances in 13 genera with a higher presence of Bacteroidales_RF16_group, Lachnospiraceae_ND3007_group, and WCHB1-41. Moreover, significant functional profiles are associated with key metabolic pathways in bacteria and are interconnected by the need to generate energy and biosynthetic precursors and to manage available nitrogen and carbon. Finally, eight bacterial genera were identified as biomarkers correlated with the increase in VFA in EG-44DPS. Full article