SNP#30: Melatonin, Meal Timing & Chrononutrition – Marta Garaulet, PhD

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Introduction

In this interview, we will explore the role of circadian biology in human health and metabolism. We will begin by examining circadian clocks, the internal mechanisms that regulate our daily physiological cycles, and how these differ from behavioral cycles, which are influenced by external factors such as light exposure and activity levels. This distinction is important for understanding the roles of circadian phase and melatonin, two biological drivers that affect our metabolic processes and overall well-being.

We will also discuss the diurnal variation in glucose tolerance, a phenomenon where the body’s ability to process glucose changes throughout the day. This discussion will reference studies from 2013 and 2015 from our guest’s lab, which investigated the benefits of consuming the largest meal earlier in the day for metabolic health. These studies have contributed to ongoing discussions about the relationship between meal timing and glucose control, particularly in the context of endogenous melatonin levels and their impact on glucose metabolism during the biological night.

Finally, we will touch upon ongoing research, including the ONTIME-MT study, which examines the interaction between obesity, nutrigenetics, and meal timing within the context of a Mediterranean diet and melatonin levels. We will also discuss the concept of dim-light melatonin onset and its implications for defining “late dinners” based on individual circadian rhythms and melatonin onset times. This conversation will provide insights into current and future research directions in this field.

Related resources

Overview

Guest Information

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Marta Garaulet Aza is a Doctor of Pharmacy, Nutritionist and Master in Public Health from Harvard University (USA), as well as Professor of Physiology and Physiological Bases of Nutrition at the University of Murcia.

Her teaching and research activity has always been related to nutrition issues, especially chrononutrition and obesity, publishing more than 200 scientific articles in high impact journals in her area. Her research has been crucial for the discovery of the importance of mealtimes.

She is currently a Research Collaborator at Brighams and Women’s Hospital (Harvard University) and is a member of the steering committee of different scientific societies such as the Spanish Nutrition Foundation (FEN), and is also a Full Member of the National Academy of Nutrition.

Marta Garaulet Aza
a Doctor of Pharmacy, Nutritionist and Master in Public Health from Harvard University (USA)

Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.

Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.

Danny Lennon
MSc. in Nutritional Sciences from University College Cork

Introduction to this Episode

In this interview, we will explore the role of circadian biology in human health and metabolism.

We will begin by examining circadian clocks, the internal mechanisms that regulate our daily physiological cycles, and how these differ from behavioral cycles, which are influenced by external factors such as light exposure and activity levels. This distinction is important for understanding the roles of circadian phase and melatonin, two biological drivers that affect our metabolic processes and overall well-being.

We will also discuss the diurnal variation in glucose tolerance, a phenomenon where the bodyʼs ability to process glucose changes throughout the day. This discussion will reference studies from 2013 and 2015 from our guestʼs lab, which investigated the benefits of consuming the largest meal earlier in the day for metabolic health.

These studies have contributed to ongoing discussions about the relationship between meal timing and glucose control, particularly in the context of endogenous melatonin levels and their impact on glucose metabolism during the biological night.

Finally, we will touch upon ongoing research, including the ONTIME-MT study, which examines the interaction between obesity, nutrigenetics, and meal timing within the context of a Mediterranean diet and melatonin levels.

We will also discuss the concept of dim-light melatonin onset and its implications for defining “late dinners” based on individual circadian rhythms and melatonin onset times. This conversation will provide insights into current and future research directions in this field.

Useful Terminology for this Episode

Key Terms & Acronyms
  • Chrononutrition: The study of how the timing of food intake affects metabolic health and overall well-being, emphasizing the synchronization of eating patterns with the body’s circadian rhythms.
  • Circadian Rhythms: 24-hour cycles in the physiological processes of living organisms, driven by an internal biological clock, which regulate sleep-wake cycles, hormone release, and other vital functions.
  • Suprachiasmatic Nucleus (SCN): A small region in the hypothalamus of the brain that acts as the master clock, coordinating circadian rhythms throughout the body.
  • Dim-light Melatonin Onset (DLMO): The time at which melatonin levels start to rise in dim light conditions, marking the beginning of the biological night and used as a marker for circadian phase.
  • Insulin Sensitivity: The efficiency with which cells respond to the hormone insulin, facilitating glucose uptake from the bloodstream; higher sensitivity indicates better glucose metabolism.
  • MTNR1B Gene: A gene encoding the melatonin receptor 1B, which is involved in the regulation of insulin secretion and glucose metabolism, with certain variants linked to higher fasting glucose levels and diabetes risk.
  • Postprandial Glucose Response: The change in blood glucose levels following a meal, reflecting how effectively the body metabolizes food.
  • Beta-cell Function: The ability of pancreatic beta cells to produce and secrete insulin in response to blood glucose levels, crucial for maintaining glucose homeostasis.

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