Chrono‐nutrition – an emerging, modifiable risk factor for chronic disease?

Everything around us has a rhythm, including the internal processes in our body. These are called circadian rhythms since they occur 24-h cycle (from Latin circa = and dia day). During COVID-19 pandemic, many people have seen their normal daily routine disrupted may changed timing of eating sleeping. changes sleeping had metabolic effects. Over past decade, nutrition researchers incorporated research biological temporal rhythms, chrono-biology, into research, this novel area is chrono-nutrition (Garaulet & Gómez-Abellán, 2014; St-Onge et al., 2017; Tahara Shibata, 2013). Chrono-nutrition includes distribution energy intake, meal frequency regularity, duration fasting periods, relative importance these factors for health chronic disease risk (Flanagan 2020; Pot 2016). This Virtual Issue brings together papers recently published Nutrition Bulletin discussing different aspects chrono-nutrition, sleep, breakfast consumption time-restricted feeding (Figure 1) (Clayton Darzi Edinburgh Gibson, 2018; Gibson-Moore Chambers, 2019; Lynch 2021; Ruddick-Collins 2018). Other elements such as clock time (time eating) beyond scope Issue. editorial aims to set context wider emerging field goes on discuss potential public implications considering chrono-type what findings from might mean shift workers. To understand underlying mechanisms how can affect health, it important consider works. In brief, system manages synchronises physiology behaviour world 2020). The central clock, located hypothalamic suprachiasmatic nuclei (SCN), entrained by two main signals (also zeitgebers): light food intake (Green 2008). addition, almost all tissues body peripheral clocks 2020) under control genes (i.e. genes) (Dashti 2011, 2015b). network both imposes rhythmic over virtually bodily functions, example when we feel sleepy hungry. Feeding follows strong diurnal or pattern [e.g. nocturnal rodents mice rats typically consume majority calories during active phase dark 2020)]. When were forced resting phase, gained more weight compared with that consumed isocaloric meals (Arble 2009). suggests calorie not always same effect effects depend day consumed. Human intervention studies confirmed showed responses strongly influenced at which 2013; Jakubowicz Garaulet al. one first groups observe among women who trying lose weight, those consuming before 3 pm lost than after 20-week loss 420 obesity found similar results 93 overweight beneficial high caloric evening terms loss, waist circumference, serum ghrelin lipids, appetite scores insulin resistance indices (Jakubowicz shown and/or irregularity cardiometabolic (Farshchi 2004; Farshchi 2005; Madjd 2016; Specific examples tight regulation blood levels glucose triacylglycerol (TAG). For healthy individual fasted state, 4.6 g 4–5 mmol/l. Oral tolerance tests, measure sensitivity, display rhythm usually peaks morning reduces later (Jarrett 1972; Van Cauter 1997). review examines role diet exercise mediating postprandial TAG (Edinburgh 2017). Many individuals three per thus spend waking hours state (de Castro, 2004). Exaggerated glycaemia triglyceridaemia associated diseases (Ning 2012; Nordestgaard Ingestion carbohydrates fat excursions. factors, quantity type each macronutrient well relation physical activity habitual level an individual. Sleeping night being awake also light-related rhythm. Sleep basic requirement human plays essential physiological psychological functioning (Van 2008; Vincent example, sleep cognitive performance, metabolism, regulation, immune function hormone (Vincent Disruption patterns leads endocrine alterations, intolerance (Johnston, 2014). Research shows decreased increased diseases, probably reverse J-shaped relationship optimal amount 7–8 (Zhou 2019). winners British Foundation Drummond Pump Priming award, Dr Pot, up PhD project examine quality balance, dietary quality, (Darzi First, demonstrated systematic meta-analysis partial deprivation resulted but expenditure, leading net positive balance 385 kcal/day (Al Khatib Subsequently, pilot cross-sectional study (Sleep-E study) linked lipid metabolism Lastly, extension feasible lifestyle free-living, short sleepers randomised controlled trial (SLuMBER Overall, concluded current guidelines benefit advice sleep. Chambers provides summary evidence inadequate (Gibson-Moore Although impact outcomes tends be relatively small, long-term cumulatively, contribute morbidities 2015a, five short-term restriction [including aforementioned SLuMBER 2018)] some improvements, hormones, bodyweight (Pizinger However, there need well-designed, larger longer studies, using objective measures determine whether good night's help tackle crisis Most so far specific times relate breakfast). UK, third population sometimes regularly skips (Reeves 2013) although recent pandemic. Consumption early overnight fast fundamental regulating 2020); nonetheless, complex. observational suggest possible protective against increasing adiposity (Gibney interventions do support hypothesis skipping positively influences (Chowdhury Levitsky Pacanowski, Sievert paper describes rationale Medical Council-funded Big Breakfast Study. investigate mechanistic basis amplified diet-induced thermogenesis enhanced exploring behavioural adaptations expenditure alongside biology (Ruddick-Collins briefly reports linking timing, overview undertaken part Study will provide insights involved mealtime-dependent implementing comparing morning-loaded versus evening-loaded diets obese subjects, whilst monitoring components 4-week period. needs periods order reset (Tahara Implementing extended restricted parts become increasingly popular effective method management improving health. Intermittent been ageing Cabo Mattson, humans, most widely studied intermittent-fasting regimens alternate-day fasting, 5:2 intermittent (two days week) Time-restricted (TRF) (TRE) special form based (Moon Studies explored TRF humans often feasibility wide range protocols participant characteristics limiting ability extrapolate real-life settings. Issue, Clayton describe exploration independent metabolic, endocrinal winner award conduct crossover lean, following either fasting. influence key markers (e.g. glycaemic control), information subjective experience. primary reduce improve So far, performed conditions. understanding TRE specifically use lean design late established 2 diabetes 10-week 3-arm parallel (Lynch 2021). 10 weeks low-density lipoprotein (LDL)-cholesterol sensitivity. hypothesised early-TRF induce late-TRF proposed practical earlier real life, its social interactions preferences. Both (2020) (2021) shed better restrict – question evaluating modifiable factor non-communicable diseases. only starting receive attention, given ways modern lifestyles, work, exposure prolonged artificial erratic patterns, disrupt system, large (Cornelissen Otsuka, workers, especially working night, developing (Depner Reutrakul Knutson, 2015). Despite known aetiology disease, gaps remain between (Gibson, Gibson's summarises future directions mediator With 15% UK workforce shifts 12% (ONS, 2011), could substantial, growing economy. relevant workers everybody today's society. It change throughout life course Someren, 2000). amplitude age acrophase (the period peaks) becomes variable, tending advancing Individuals ends spectrum, adolescents older adults, prone disorders. Delayed disorder (DSPD) occurs adults work jet-lag (Duffy disorders due greater inability adverse reduced age. Alterations thought symptoms age-related disorders, dementia Consideration therefore (night) shifts. further needed appropriate recommendations formulated. Understanding complex hours, nutrient affects opportunity significant proportion obesity-related taken account. Chrono-type refers individual's preferred activity/rest cycle. categorised morning, intermediate (Roenneberg 2007). stable trait minor (Druiven A number investigating chrono-type. Recent evening-type displayed unhealthy habits (Merikanto Partonen, difficult (Mazri tended (Zerón-Rugerio 2020), overweight/obesity (Baron 2011; Martínez-Lozano Xiao may, part, explain differences metabolically obesity. bedtimes, complete counterparts (Torres-Castillo Furthermore, Finland mismatch sleep–wake preference was particularly present young indicating misalignment Finnish adult if does Thus, consideration add base settings conclusion, potentially substantial implications. There urgent counteract induced modern-day Intervention should ideally practice-based taking account intra-variability day-to-day variability seasonal changes) inter-variability chrono-type). follow trends personalised likely lead one-size-fits-all approach. Evidence mitigating used formulate recommendations. knowledge already trickling through American Heart Association (St-Onge regular recommended. described inform advice. address activity. You you eat