Dietary Intake Timing (Chrono-nutrition)

Current studies focusing on the relationship between sleep and mood emphasize the need for circadian intervention methods to help avoid the development of mood disorders as a result of shift work. Shift workers are a particularly vulnerable population of employees due to the resulting circadian rhythm disturbances, subjecting them to an increase of 25% to 40% in the likelihood of suffering from anxiety and depression. In this study by Qian et al. (2022), the authors investigated the impact of shift work on mood by simulating night work plus daytime and nighttime or daytime-only eating compared to a control baseline for two weeks, in a sample of 20 participants (aged 18-35, BMI 18.5-29.9, 12 males and eight females). The authors observed an increase in anxiety and depressive symptoms in night work with nighttime and daytime eating compared to controls, however, participants who only ate during the day did not show similar results. Overall, a disruption of the normal circadian rhythm as a result of night work was noted to increase depressive and anxiety symptoms, findings that the authors highlight as a proof-of-concept for adjusting meal times as an effort to potentially ameliorate mood disturbances associated with shift work. However, more studies are necessary. [NPID: Circadian disruption, mental health, mood vulnerability, shift work, sleep]

This 2021 article focuses on the role of the gut microbial community (microbiota) as a regulator of circadian rhythms and metabolism. The microorganisms in the gut primarily can modulate host metabolism by providing input to both circadian clock-dependent and clock-independent host networks. Also known as microbial oscillators, these microorganisms’ behaviors and composition can be influenced by a variety of factors such as genetics, environmental variables, diet, gut immunity, and host sex. Plant-based, low-fat diets generally promote microbial oscillators, whereas low-fiber, high-sugar, high-fat (Western) diets can destroy most of these microorganisms. This review further discusses the ways in which these oscillators affect host circadian gene expression and metabolic state. Since the gut microbiota is unique in its role as a non-light dependent driver of host metabolism and metabolic rhythms, the development and clinical application of novel gut microbiota-related diagnostics and therapeutics have great potential in achieving and maintaining metabolic health. [NPID: gut microbiota, circadian rhythm, metabolic rhythm, metabolism, diet, Western diet, lean diet]

In this 2021 article, the authors explain that shift and night workers may be at risk of developing cancer and cardiometabolic diseases, while shift work also increases the probability of suffering from mood disorders such as depression, anxiety, and burnout syndrome. Guerrero-Vargas et al. therefore tested whether adult male Wistar rats exposed to an experimental model of shiftwork developed depression or anxiety-like behaviors. Another purpose of this experiment was to examine whether this shift-work model was linked to neuroinflammation in the areas of the brain related to mood regulation. Some rats were fed only during their active phases to determine whether this condition can prevent neuroinflammation, as well as depressive and anxiety-like behaviors. It was found that the shift-work model causes depressive-like behavior and increased anxiety-like behavior in the rats. In addition, there were several indicators of increased neuroinflammatory markers in various parts of the brain. But neuroinflammatory markers in the brain were reduced, and behavioral changes prevented by time-restricted feeding (eating only during the active phase). These results add to the existing evidence of time-restricted feeding having an important role in promoting circadian synchrony with the light-dark cycle and in preventing neuroinflammation, leading to healthy mood states even when exposed to conditions that can induce circadian disruption. [NPID: shift work, night workers, circadian rhythm, depression, anxiety, neuroinflammation, burnout, time-restricted feeding, chrononutrition, mood, meal intake timing]

This 2018 study hypothesized that the night eating syndrome (NES) feeding pattern might cause time-specific depression. Patients with night eating syndrome delay their eating rhythm and find that their mood declines during the evening and night, manifesting as time-specific depression. In this study, a night eating syndrome model was developed and tested on mice. This new model involved free access to a normal-fat diet but restricted feeding with a high-fat diet during the inactive period. Lights were switched on and off at times to reflect evening and early night for humans. The forced swimming test, which indicates depressive-like behavior, showed longer immobility time in the night eating syndrome (NES) model only after lights-on. Also, production of neurotransmitters such as serotonin and norepinephrine increased in the night eating syndrome model. However, the utilization and metabolism of these chemicals decreased under stress. Desipramine, an antidepressant, shortened the immobility time of some mice under the NES condition in the forced swimming test. These results suggest that this feeding pattern mimicking the night eating syndrome causes malfunction of the monoamine system, possibly contributing to the development of time-specific depression. [NPID: time-specific depression, forced swimming test, night eating syndrome, eating rhythm, chrononutrition]

This 2019 study monitored the daily dietary and macronutrient intake of children at 4 years old, and then examined their body mass index (BMI) at 7 years old. The purpose of this cohort was to investigate if timing of food and macronutrient consumption at 4 years old affects weight status at 7 years old. The results showed that 4-year-olds with a relatively higher energy intake at lunch and dinner or at mid-afternoon were more likely to be overweight/obese three years later. Consuming a relatively higher amount of fat at lunch was also associated with being overweight or obese at 7 years old. These relationships were independent of the effect on children's eating behaviors related to appetite. Moreover, this study identified a detrimental correlation between breakfast skipping and eating later in the day with body weight. It appears that eating a higher proportion of energy and macronutrients during the main meals and consuming a lower proportion during the afternoon and evening is more beneficial to children’s weight. These results highlight the extent to which daily food intake rhythm influences weight gain during childhood. [NPID: childhood, food intake rhythm, chrononutrition, food intake timing, breakfast skipping, meal timing, meal patterns]

The influence of our gut microbiome on wellbeing extends well beyond our digestive system, up to the interactions and harmony we achieve between one another. The influence of relationships on the gut microbiome, and the subsequent impact on dietary choices, remains poorly understood. To further study the relationship between the gut microbiome and behavioral patterns, Di Stefano et al. (2019) examined the "gut-human behavior axis" and its evolving mechanisms through complex social scenarios in real life. Taking into account the concepts of personality and gut homophily (the practice where individuals seek like-minded/similar others), psychological and other unconscious sources of bias, the authors investigated the relationship between social interactions and gut microbiota, evaluating how dietary choices impacted behavioral patterns and gut microbiota composition, and vice versa. It was observed that the times of the day meals are consumed significantly affected feeding behavioral patterns, in addition to type and amount of food consumed (i.e., chrono-nutrition). By examining shift workers, the authors looked at the relationship between gut microbiome and dietary behaviors from a chrono-nutrition perspective. The results set the foundation for a quantitative framework that may be used to measure the interaction between human conduct and the gut microbiome. Furthermore, the authors comment that the chronological timeline of gut microbiome lags behind shift work and social contact, thus it is postulated that shift work affects chrononutrition variably, in terms of both meal timing and quality of consumed meals (which tend to gravitate towards high-fat meals in shift workers). In conclusion, the authors believe that understanding the social factors impacting gut microbiome and our dietary conduct and choices will further our understanding of the underlying metabolic mechanisms and their impact on overall human health, which may lead to the development of novel socially-focused therapeutic dietary treatments. [NPID: Chrono-nutrition, dietary patterns, gut microbiome, feeding behavior, shift work]

The objective of this 2021 study was to examine the relationship between food intake timing and cognition in a sample of adults living in Southern Italy. Manipulation of feeding/fasting timing has emerged as an innovative strategy to fight and treat cognitive decline. In this study, 883 adults living in Sicily were given food frequency questionnaires to complete. Demographic and dietary characteristics were identified, including the time window between the first and the last meal of an average day. If the time difference between the first and last meal was on average less than 10 hours, the individual was identified to practice time-restricted feeding. After adjusting the analysis models for potential confounding factors, these participants who showed time-restricted feeding were reported to be at lower risk of having cognitive impairment, compared to those with no eating time restrictions. A similar relationship was found among people who have a breakfast meal, but this association was not seen among those who eat meals for dinner. In conclusion, time-restricted eating appears to have considerable effects on brain health and may be positively related to cognitive status. [NPID: brain health, chrononutrition, time restricted eating, time restricted feeding, Italy, Italian, cognition, cognitive status, breakfast, dinner]

In this 2021 study, 192 students were asked to complete a questionnaire on preferred timing of eating, and actual chrononutrition (the timing of food intake) behaviors. The participants were aged between 18 to 31 years. The aim of this study was to examine the extent to which people’s ideal eating schedule matches their actual consumption timing. This discrepancy between chrononutrition preferences and chrononutrition behaviors is called eating misalignment. After administering the questionnaires (the Chrononutrition Profile Questionnaire), Veronda & Irish found that there was high variability in eating misalignment between these students. The results showed extreme cases of eating misalignment across all aspects of chrononutrition. These findings confirm that when individuals want to eat may differ from when they eat. [NPID: chrononutrition, eating behaviors, eating misalignment, circadian]

The purpose of this 2021 study was to investigate the relationship between time-restricted feeding and mental health outcomes in southern Italian adults. Since the growing mental health problems seem to be influenced by modern society, unhealthy lifestyle, and harmful dietary habits, some people have suggested dietary strategies such as feeding regulation and fasting to prevent and treat mental health diseases. In this present study, food frequency questionnaires were used to calculate the dietary consumption of 1572 adults. The participants were asked what time, on average, they consumed their meals. The researchers wanted to find out who was eating within 8 hours or less of their previous meal. These dietary characteristics were then analyzed on their correlations with depressive symptoms, perceived stress, and sleep quality. Time-restricted feeding was not related to mental health outcomes after adjusting the analysis model for potential confounding factors. However, there were notable results when performing the analyses by age groups. Individuals over 70 years old with feeding time windows of 8 hours were less likely to exhibit signs of mental health issues than those with no feeding time restrictions, regardless of the quality of their diets. This relationship was maintained after adjusting for having dinner but disappeared after adjusting for having breakfast. In conclusion, restricting the daily feeding window of time is linked with fewer symptoms of mental health distress in adults older than 70 years. [NPID: mental health, restricted eating, restricted feeding, fasting, timing, chrononutrition, Italian, Italy]