Nutrients

Background/Objectives: The aim of this study was to compare the different forms of caffeine (CAF) administration in CrossFit^® participants. The countermovement jump (CMJ), the rate of perceived exertion (RPE), the total number of repetitions, and the maximum (HR_max) and mean heart rate (HR_mean) were evaluated. Methods: Fourteen males with more than six months of continuous CrossFit^® training (30.9 [5.62] years, 179 [1.33] cm, 78 [5.75] kg, 24.3 [1.33] kg·m⁻²) participated in this randomized, placebo-controlled, crossover study. Participants were randomized in a repeated measures design using caffeine capsule (CC), caffeine chewing gum (CCG), and caffeine mouth rinse (CMR) protocols, along with a placebo group (PG). Participants were unaware of whether any of the delivery methods contained caffeine. A 7-day washout period before each crossover was used. To ensure ecological validity, we replicated the real-world practice of CAF ingestion 30 min prior to training, mirroring typical athlete pre-workout routines. The participants of CrossFit^® performed the ‘Cindy’ protocol, and the CMJ as a primary outcome was measured pre- and post-intervention, while the RPE, HR, and the number of repetitions were tracked at the end of the workout for comparisons. Results: No significant differences were found between CAF forms in internal load measures (RPE, HR_max, HR_mean) or the number of repetitions. While no changes were observed with other CAF forms, CMR significantly improved the CMJ performance compared to the baseline (Δ: +3.5; Cohen’s d_unb: 0.51], which exceeded the estimated SWC by approximately three-fold. However, the inferential analysis revealed no significant main effects of the caffeine administration method on any measured outcomes. Conclusions: While CAF delivery forms did not improve internal load measures or performance parameters, such as the RPE, HR, or the total number of repetitions, the caffeine mouth rinse (CMR) showed a potentially meaningful improvement in CMJ performance after CrossFit^® training in participants with a certain level of experience.

Background/Objectives: This study aimed to examine levels of food agency and intentions to improve cooking skills among Korean young adults in their 20s, and to identify demographic differences and underlying motivators. Subjects/Methods: An online survey was administered from February 18 to 25, 2021, targeting Korean adults aged 20–29 years (n = 1102; 579 men, 523 women). Food agency was assessed using the Cooking and Food Provisioning Action Scale (CAFPAS), comprising three subscales: self-efficacy (13 items), attitude (10 items), and structure (5 items). Participants also reported their intentions to improve cooking skills and the motivators behind those intentions. Reliability of multi-item measures was confirmed using Cronbach’s alpha. Descriptive statistics were calculated for all study variables. Demographic differences in food agency and intentions were analyzed using independent t-tests and one-way ANOVA. Open-ended responses were analyzed using qualitative content analysis to explore key motivators. Statistical analyses were performed using SPSS Statistics 28.0 (α = 0.05). Results: Food agency scores were significantly lower among university graduates, employed individuals, and those from lower-income households. Single-person households reported significantly higher self-efficacy and attitude scores, while structure scores were significantly lower in this group. Lower structure scores were also observed among women; university graduates or individuals with higher levels of education; employed respondents; and those belonging to the low-income group. Intentions to improve cooking skills were significantly higher among women and single-person households. Qualitative analysis identified media influence and the demands of independent living as primary motivational drivers. Conclusions: These findings highlight the need for targeted interventions to enhance structural capacity for food agency, particularly among women, employed individuals, those with higher education, and people in the low-income range. Efforts should focus on leveraging media influence and supporting individuals adapting to independent living to promote cooking skill development.

Background/Objectives: Among more than 300 candidate genes for obesity, FTO, MC4R, and BDNF have been approved for DTC genetic testing. However, population-specific evidence supporting their relevance to obesity-related phenotypes in Koreans remains limited. Methods: A total of 231 healthy adults aged 19–64 years were recruited between March and May 2024. Anthropometric and clinical measurements, genotyping, dietary intake, and questionnaires on socioeconomic status, family history, and lifestyle behaviors were obtained. Associations between genotypes and obesity-related phenotypes were evaluated using ANOVA and ANCOVA, multivariable-adjusted models and multicollinearity analysis-based stepwise regression. Results: In Koreans, MAFs for FTO (3 SNPs), MC4R rs17782313 and BDNF rs6265 were 13–16%, 27.1% and 47.4%, respectively. OB frequency (%) differed significantly between BDNF GG and A allele carriers (p < 0.05). Compared to GG, BDNF A allele carriers showed higher WHR, ALT, HbA1c and sodium intake (p < 0.05). BDNF A allele carriers were observed to have higher drinking frequency and elevated ALT levels. Significant genotype–obesity interactions were identified for RMR/BW status, dietary fiber, Vit E, folate, P, K, cholesterol, and PUFA (p < 0.05). Among A allele carriers, OB-related indicators (BMI, RMR, WHR) were independently associated with age, sex, RMR, SBP, ALT, leptin, and dietary intakes of Vit A and sugars. Conclusions: These findings support the relevance of BDNF rs6265 in obesity phenotypes among Korean adults and provide Korean-specific evidence for genotype-based nutrition strategies. Given the cross-sectional study, the interpretation of personalized nutrition approaches for genetic risk carriers should be made with caution.