bims-ciryme Biomed News
on Circadian rhythms and metabolism
Issue of 2022‒01‒09
three papers selected by
Gabriela Da Silva Xavier
University of Birmingham

  1. Acta Physiol (Oxf). 2022 Jan 04. e13770
      In mammals, physiology and metabolism are shaped both by immediate and anticipatory responses to environmental changes through myriad of molecular mechanisms. While the former is mostly mediated through different acute signaling pathways the latter is primarily orchestrated by the circadian clock. Oxygen is vital for life and as such mammals have evolved different mechanisms to cope with changes in oxygen levels. It is widely accepted that oxygen sensing through HIF-1 signaling pathway is paramount for the acute response to changes in oxygen levels. Circadian clocks are molecular oscillators that control 24 h rhythms in various aspects of physiology and behavior. Evidence emerging in recent years points towards pervasive molecular and functional interactions between these two pathways on multiple levels. Daily oscillations in oxygen levels are circadian clock controlled and can reset the clock through HIF-1. Furthermore, the circadian clock appears to modulate the hypoxic response. We review herein the literature related to the crosstalk between the circadian clockwork and the oxygen-signaling pathway in mammals at the molecular and physiological level both under normal and pathologic conditions.
    Keywords:  Circadian Clocks; Daily Rhythms; HIF-1; Metabolism; Oxygen; Physiology
  2. Int J Obes (Lond). 2022 Jan 08.
      The quality and quantity of nutrition impact health. However, chrononutrition, the timing, and variation of food intake in relation to the daily sleep-wake cycle are also important contributors to health. This has necessitated an urgent need to measure, analyze, and optimize eating patterns to improve health and manage disease. While written food journals, questionnaires, and 24-hour dietary recalls are acceptable methods to assess the quantity and quality of energy consumption, they are insufficient to capture the timing and day-to-day variation of energy intake. Smartphone applications are novel methods for information-dense real-time food and beverage tracking. Despite the availability of thousands of commercial nutrient apps, they almost always ignore eating patterns, and the raw real-time data is not available to researchers for monitoring and intervening in eating patterns. Our lab developed a smartphone app called myCircadianClock (mCC) and associated software to enable long-term real-time logging that captures temporal components of eating patterns. The mCC app runs on iOS and android operating systems and can be used to track multiple cohorts in parallel studies. The logging burden is decreased by using a timestamped photo and annotation of the food/beverage being logged. Capturing temporal data of consumption in free-living individuals over weeks/months has provided new insights into diverse eating patterns in the real world. This review discusses (1) chrononutrition and the importance of understanding eating patterns, (2) the myCircadianClock app, (3) validation of the mCC app, (4) clinical trials to assess the timing of energy intake, and (5) strengths and limitations of the mCC app.
  3. Am J Clin Nutr. 2022 Jan 03. pii: nqab433. [Epub ahead of print]
      Chronobiology plays a crucial role in modulating many physiological systems in which there is nutritional synergism with meal timing. Given that intermitting fasting (IF) has grown as a flexible dietary method consisting of delayed or early eating windows, this scoping review addresses the effects of IF protocols on metabolism as they relate to clinical nutrition and the circadian system. While nocturnal habits are associated with circadian misalignments and impaired cardiometabolic profile - and nutritional physiology is better orchestrated during the day - most findings are based on animal experiments or human studies with observational designs or acute meal tests. Well-controlled randomized clinical trials employing IF protocols of delayed or early eating windows have sometimes demonstrated clinical benefits, such as improved glycemic and lipid profiles, as well as weight loss. However, IF does not appear to be more effective than traditional diets at the group level, and its effects largely depend on energy restriction. Thus, efforts must be made to identify patient biological rhythms, preferences, routines, and medical conditions before individual dietary prescription in clinical practice.
    Keywords:  cardiovascular disease; diabetes; intermittent fasting; time-restricted eating