Optimal cognitive functions are necessary for activities of daily living and self-independence. Cognitive abilities are acquired during early childhood as part of progressive neurodevelopmental milestones; unfortunately, regressive changes can occur as part of physiological aging, or more ominously, pathological diseases, such as Alzheimer’s disease (AD). Cases of AD and its milder subset, mild cognitive impairment (MCI), are rising and would impose a burdensome impact beyond the individual level. Various dietary and nutritional approaches have potential for promising results in managing cognitive deterioration. Glucose is the core source of bioenergy in the body; however, glucose brain metabolism could be affected in aging cells or due to disease development. Ketone bodies are an efficient alternate fuel source that could compensate for the deficient glycolytic metabolism upon their supra-physiologic availability in the blood (ketosis), which, in turn, could promote cognitive benefits and tackle disease progression. In this review, we describe the potential of ketogenic approaches to produce cognitive benefits in healthy individuals, as well as those with MCI and AD. Neurophysiological changes of the cognitive brain in response to ketosis through neuroimaging modalities are also described in this review to provide insight into the ketogenic effect on the brain outside the framework of purely molecular explanations.

Interacting with nature may promote mental and physical health. There are multiple ways to interact with nature: indirectly, incidentally, and intentionally. How these types of interactions with nature may be associated with mental and physical health status and health behaviors is unclear. The purpose of this narrative review is to (1) describe the relationship between interactions with nature (indirect, incidental, and intentional) and mental and physical health outcomes and behaviors, (2) identify gaps in the literature, and (3) provide recommendations for future research. Considerable evidence suggests that interacting with nature, indirectly and intentionally, is associated with improvements in mental health and physical exhibitions of mental status. Furthermore, intentionally interacting with nature is associated with engagement in physical activity and gardening is associated with fruit and vegetable consumption. Research suggests that incidentally interacting with nature may be associated with positive mental health status. More research is needed to understand the relationships between incidental interactions with nature and physical health status and behaviors; as well as among all types of interactions with nature and physical health disorders, sleep, and dietary behaviors.

Background: Interleukin‐15 (IL‐15) is a myokine associated with muscle strength, possibly by attenuating protein breakdown. A variant in the alpha‐receptor (IL‐15Rα 1775 A>C, rs2228059) partially modulates the muscle strength and size response to resistance training. We examined if this polymorphism associated with habitual physical activity among European‐American adults.Methods: Men (n = 240, 23.7 ± 0.3 year, body mass index [BMI] 25.3 ± 0.3 kg/m²) and women (n = 292, 23.2 ± 0.3 year, 24.0 ± 0.3 kg/m²) were genotyped. Physical activity phenotypes were derived from the Paffenbarger Physical Activity Questionnaire. Analysis of covariance (ancova) tested log‐transformed differences between the IL‐15Rα genotype and physical activity phenotypes by gender with age and BMI as covariates.Results: Men with the IL‐15Rα 1775AA genotype spent more time in light intensity physical activity (39.4 ± 2.4 hr/week) than men with the CC genotype (28.6 ± 2.3 hr/week, (p = .009).Conclusion: Further research is needed to confirm our finding and determine the possible mechanisms by which the IL‐15Rα variant modulates light intensity physical activity.

The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism (rs4340) (ACE DIP) accounts for half of the variability in plasma ACE concentrations. ACE has been widely studied for its influence on sports performance; however, research on its influence in physical activity is limited and inconsistent. We examined the influence of the ACE DIP on physical activity among 461 European Americans. Subjects completed the Paffenbarger Physical Activity Questionnaire for weekly walking distance. Multivariate analysis of covariance (MANCOVA) tested log-transformed differences in weekly walking distance among ACE DIP genotypes (II, ID, DD) with gender as a fixed factor, and age and body mass index (BMI) as covariates. Because we found a significant ACE DIPxBMI interaction (P = 0.03), we categorized the sample by normal weight (NW: BMI<25.0 kg/m²) and overweight (OW: BMI ≥25.0 kg/m²) and repeated the MANCOVA with multiple comparison adjustments. NW adults with ACE II walked 15.8 ± 11.1 km/week, ID 13.2 ± 10.6 km/week, and DD 17.9 ± 13.0 km/week, with ID walking less than II (P = 0.03) and DD (P = 0.01). OW adults with ACE II walked 16.7 ± 12.6 km/week, ID 13.8 ± 11.6 km/week, and DD 9.7 ± 9.0 km/week, with DD walking less than II (P = 0.02). Weekly walking distance was 8.2 ± 2.4 km/week less among OW adults with ACE DD than NW (P = 0.02). BMI interacted with ACE DD such that OW walked ~8.2 km/week less than NW, potentially equating to a body weight differential of ~3.5 kg annually.

Interacting with nature, such as spending time in nature and having houseplants, has been associated with positive mental and physical health outcomes and behaviors but limited research has explored dietary behaviors. Therefore, this study examined the relationships among interactions with nature, diet quality, and sustainable dietary patterns. In this explanatory sequential mixed methods study, participants self-reported the frequency and duration of their interactions with nature and completed Diet History Questionnaire II, where Healthy Eating Index-2020 (diet quality) and EAT-Lancet Index (sustainable dietary pattern) scores were calculated. A purposive sample of participants completed an interview. Multiple regression models were used to analyze quantitative data. Qualitative data were thematically analyzed. The data were integrated by connecting and merging. Three hundred adults completed the survey and 30 were interviewed. Positive significant relationships among interactions with nature, diet quality (p < .001), and sustainable dietary patterns (p < .001) were found. Four themes highlighted how interacting with nature may affect dietary intake: engaging with the natural world relaxes the mind, paving the way for healthier eating habits; pursuing health draws us toward nature and positively influences dietary choices; a deep connection to nature sparks a desire to nourish the body with more fruits and vegetables; and thoughtfully participating in the food system promotes healthier choices for personal and planetary health. Integrated findings highlight that mental state moderates and connection to nature mediates the relationships of interest. These results may be used to promote dietary behaviors for personal and planetary health through nature-based interventions.

“Loss of control, LOC” eating is a major contributor to the development of obesity. Dietary protein is known to promote satiety, but little attention has been paid to the ability of protein, consumed in close proximity to snacking (20 min), to reduce the intake of ultra-processed, low-protein snack foods. We hypothesized that a high-protein preload (HP, 8 g of protein) consumed in close proximity to eating an ultra-processed snack food would reduce intake of the snack food as compared to a low-protein preload (LP, 1.2 g of protein). Two laboratory test meals were conducted, and the intake of ice cream (1.99 kcal/gram) after consuming dairy-based liquid preloads was measured. Habitual physical activity, a potential modulator of satiety, was assessed by a self-reporting questionnaire. Thirty (responders) out of 50 participants reduced their intake of ice cream after the HP preload, with a significant difference in intake observed between the responders and non-responders (−30 ± 25 and 18 ± 18 g, F (1, 49) = 54.36, p < 0.001 for responders and non-responders, respectively). Our data demonstrate that protein consumed in close proximity to ultra-processed snack food can reduce caloric intake by ~60 kcal, which could potentially reduce body weight by at least 5 pounds per year.