Dietary polyphenols (DPs) have garnered growing interest because of their potent functional properties and health benefits. Nevertheless, the antioxidant capabilities of these substances are compromised by their multifarious structural compositions. Furthermore, most DPs are hydrophobic and unstable when subjected to light, heat, and varying pH conditions, restricting their practical application. Delivery systems based on the interactions of DPs with food constituents such as proteins, polypeptides, polysaccharides, and metal ions are being created as a viable option to improve the functional activities and bioavailability of DPs. In this review, the latest discoveries on the dietary sources, structure–antioxidant activity relationships, and interactions with nutrients of DPs are discussed. It also innovatively highlights the application progress of polyphenols and their green nutraceutical delivery systems. The conclusion drawn is that the various action sites and structures of DPs are beneficial for predicting and designing polyphenols with enhanced antioxidant attributes. The metal complexation of polyphenols and green encapsulation systems display promising outcomes for stabilizing DPs during food processing and in vivo digestion. In the future, more novel targeted delivery systems of DPs for nutrient fortification and intervention should be developed. To expand their usage in customized food products, they should meet the requirements of specific populations for personalized food and nutrition.

Background: Nitrate is a dietary intervention commonly used to enhance exercise capacity, including cardiopulmonary fitness, yet its effectiveness has been recently questioned at high altitudes. This meta-analysis systematically evaluates the effects of dietary nitrate supplements on cardiopulmonary fitness at high altitude, as reflected in the biomarker of cardiopulmonary fitness, paving the way for informed dietary strategies. Methods: We conducted a systematic assessment and meta-analysis of randomized controlled trials to examine the effects of dietary nitrate supplementation on biomarkers of cardiorespiratory health at high altitude. Studies were included if they involved healthy individuals (≥16 years of age) engaging in endurance activities such as hiking, long-distance running, mountain climbing, or bicycling at high altitude. Outcomes of interest included nitrite levels (NO₂-), maximal oxygen uptake (VO_2max), heart rate (HR), perceived exertion (RPE), and pulse oxygen saturation (SpO₂). Exclusion criteria included duplicate publications, non-human studies, studies with missing data that could not be retrieved, non-randomized clinical trials, and non-original research articles such as conference papers, expert consensus, or reviews. Our search for articles was conducted across PubMed, Scopus, Web of Science, and Embase, without any language restrictions. A random effects model was employed for quantitative data analysis, utilizing Standardized Mean Difference (SMD) and 95% confidence intervals as summary statistics. The methods and results were reported according to the PRISMA2020 statement. Results: A total of 9 studies with a sample size of 161 cases were included in the analysis. The meta-analysis indicated that dietary nitrate supplement significantly elevated NO₂^- concentration (95% CI: 1.38 to 3.12; SMD = 2.25, P < 0.00001; I² = 70%). However, there was no significant effect observed on VO_2max (95% CI: -0.58 to 0.23; SMD = -0.17, P = 0.76; I² = 0%), HR (95% CI: -0.31 to 0.23; SMD = -0.04, P = 0.77; I² = 0%), RPE scores (95% CI: -0.49 to 0.18; SMD = -0.16, P = 0.36; I² = 0%), and SpO₂ percentage (95% CI: -0.36 to 0.20; SMD = -0.08, P = 0.58; I² = 0%). Conclusions: The current meta-analysis indicates that dietary nitrate intake is less correlated with cardiopulmonary fitness at high altitudes, and further research is required to clarify its impact on exercise capacity.

Kumquat polyphenols, known for their antioxidant, anti-inflammatory, have been less studied for their potential to delay aging and enhance cognitive memory. This research involved extracting and analyzing free and bound phenols from oil-skinned kumquat (Fortunella japonica Swingle) for their antioxidant and anti-aging effects. Whole fruit free phenols (WFP) at low dose (WFP-L, 50 mg per kg per day) and high dose (WFP-H, 200 mg per kg per day) were administered to D-galactose-induced senescence model mice over six weeks, examining their impact on cognitive memory function and intestinal flora. Peel free phenols and seed-bound phenols displayed the strongest activities, with key compounds like quinic acid and p-hydroxybenzoic acid identified. WFP significantly reduced oxidative stress in aging mice, enhanced antioxidant capacity, lowered inflammatory markers and acetylcholinesterase activity in the hippocampus, and increased acetylcholine levels. By modulating the p53/SIRT1/NF-κB signaling pathway, WFP effectively delayed aging and cognitive decline. Furthermore, WFP improved intestinal microbial communities, regulating flora imbalances and enhancing the intestinal barrier by boosting beneficial bacteria and reducing harmful strains like Bacteroides and Escherichia-Shigella. These findings highlight kumquat polyphenols’ therapeutic potential against age-related cognitive impairment.