Sigma Nutrition Radio

Links: Episode page Subscribe to Premium Live event in London, UK Description: Meal timing has been a popular, and at times controversial, topic of interest in nutrition. Despite much speculation over the years as to potential advantages to specific meal timing or meal frequencies, for many outcomes there seems to be little pragmatically meaningful difference. For example, when accounting for calorie and macronutrient intake, there is little to no effect of meal timing on body composition, blood pressure, and energy expenditure. However, just because there is little evidence for the importance of meal timing in relation to those outcomes, this should not be interpreted to mean there is no impact of meal timing on all health outcomes. One area where meal timing may be an important factor is in relation to glucose tolerance and glycaemic control. For example, it has been consistently shown that eating at 'biological night' leads to worse postprandial glucose responses. And this could be particularly important for those with insulin resistance, pre-diabetes or type 2 diabetes. Some of the most influential work in this area has been done by Marta Garaulet's lab at the University of Murcia. One of the central aspects they have published on has been the interaction between food timing and melatonin levels, and how this in turn affects glucose tolerance and cardiometabolic markers. In this episode, Danny and Alan discuss the topic of meal timing and glucose tolerance, using a recent study from Garaulet et al. to highlight some important concepts.

Research in the field of 'chrononutrition' has continued to grow in the past couple of years, with some important studies being published in recent times. Chrononutrition is a research area that looks at the relationship between temporal (time-related) eating patterns, circadian rhythms, and metabolic health. While past podcast episodes have covered various aspects of chrononutrition, the latest research has added important pieces to the puzzle and has lead to both Alan and Danny updated their views on certain sub-topics. In this episode, we look at recent research (including that from the Big Breakfast Project) and how understanding and conclusions from the field have shifted over time. Dr. Flanagan also gives some insight into the important chrono work published in the UK, which his dotoral work contributed to. Links: Episode page Subscribe to Premium Live event: London

There is almost universal agreement that excess added sugar in the diet is detrimental to health. However, much of this negative health impact clearly relates to the ability of high sugar intakes to drive excess calorie intake and fat accumulation, which cause health issues. But what about situtaions of where there is not a calorie surplus (hypercaloric diet) or weight gain? Some people claim that sugar is inherently damaging. While others push back and claim sugar is only a problem in the context of a hypercaloric diet. So which position is more accurate? What evidence do we have? In this episode, Dr. Alan Flanagan and Danny Lennon take a look at situations of eucaloric (or even hypocaloric) diets, and what impact sugar has. Specifically, they investigate: in a situation where someone is not overconsuming calories or gaining weight, what health impacts do added sugars have? And if there are these calorie-independent effects, at what thresholds do they occur? Links: Episode page (incl. all links) Live event: London, UK - March 2023

This episode brings you a "debate" between Danny Lennon and Dr. Jackson Peos on the utility of intuitive eating. Specifcally, they make a case for and against, respectively, for the position: "Intuitive eating can be recommended eating approach for those with fitness and/or physique goals". This episode is a Premium-exclusive episode, so you'll need to be a Premium subscriber to listen to the full discussion but you can hear a preview here. Links: Subscribe to Premium Live event: London, UK - March 2023 Buy UEBC 22 Replay

Iron is an important nutrient for athletes, given that it is used for oxygen transport and energy production. However, research on athletes often reports a relatively high prevalence of iron deficiency. Common symptoms of low iron status like lethargy, fatigue and negative mood states are naturally of concern to athletes. But there is also the potential for low iron to directly impact work capacity. Therefore, maintaining adequate iron status (and knowing the signs of iron deficiency) is crucial for athlete health and performance. In this episode, Professor Pete Peeling of the University of Western Australia discusses the role of iron in performance, iron deficiency in athletes, the impact of exercise-induced inflammation, and other important issues. Links: Episode page Live event: London, UK - March 2023

Iron deficiency is a prevalent issue. Worldwide, it is the leading nutritional deficiency. And although there is lower prevalence in high-income countries, a significant number of people are still affected. Iron deficiency may be a result of too little iron coming in (i.e., via diet choices or low absorption), or from excess losses (e.g., commonly from blood losses). Understanding how these can impact iron status is crucial for both accurate diagnosis and treatment. In relation to dietary iron, the source of iron is a common talking point, as there are two forms of iron that we can consume. Heme iron is found in meat, fish, and poultry, while non-heme iron is found in plant foods. It is known that heme iron is more readily absorbed than non-heme iron. However, there is much more to this story that makes things complicated. To discuss some of the nuances of iron bioavailability, absorption, and metabolism, leading expert in the area Professor Paul Sharp of King's College London is on the podcast. Prof. Sharp discusses crucial aspects of dietary iron sources, bioavailability, supplementation, and impacts in the body. Links: Episode page (with links/resources) Subscribe to Premium Live event: London, UK - March 2023

Iron is involved in a whole range of biological processes and a consistent supply of iron is crucial for cellular turnover. But despite iron being an essential mineral for human function, it is highly toxic to cells and tissues if present at high levels. Therefore an intricate and tight regulation of iron is necessary. If iron status gets too low, iron-deficiency anaemia can result. In such situations there is a shortfall in hemoglobin production, which leads to a range of issues in the body. So how is iron status measured? Which biomarkers are most useful? Where can errors in diagnosis occur? What problems arise with iron deficiency? And what problems occur with iron overload? In this episode, these questions (and more) are put to Dr. Austin Baraki, a practicing Internal Medicine physician and Assistant Professor of Medicine at William Beaumont Army Medical Center in Texas. This episode is the first in a three-part series on iron. Links Episode page & relevant links Subscribe to Premium Live event in London

The current food environment is continuously highlighted as a problem for public health. And so there is a strong focus in both public policy and research circles to determine which strategies could lead to a healthier food environment. One potential strategy that is widely recommended by public health experts is the use of fiscal/taxation policies to decrease the consumption of unhealthy foods and beverages. By making unhealthy foods and beverages relatively more expensive than healthy foods and beverages it is hoped that this would alter the composition of the average diet in a favorable manner. This is based on economic theory and evidence showing that most foods are relatively price "inelastic". This means that increases in the prices of particular foods can be expected to lead to reductions in the purchase of those foods. But there have also been some concerns raised about the potential effectiveness of strategies aimed at taxing a certain nutrient (e.g. sugar) or a group of foods. There are worries that such policies wouldn't lead to healthier diets; with people either not changing behavior or just substituting in other processed foods that industry has formulated to avoid a specific nutrient tax. So what does the current evidence say? With a number of countries having implemented a range of taxes or health levies, what lessons can we learn from these? And what does the best public health nutrition currently tell us about the likely effectiveness of different policies or interventions? To get to some evidence-based answers, Dr. Kathryn Backholer, an Associate Professor at Deakin University, is on the podcast to discuss the current state of the evidence on various taxes and levies on different nutrients and unhealthy foods. Links: Episode page Subscribe to Premium Live event in London

In October 2022, Ruddick-Collins et al. published results of an RCT looking at the impact of different calorie distributions across the day. This study was from the 'Big Breakfast Study' project, primarily from the University of Aberdeen. In this study, 30 subjects underwent two 4-week calorie-restricted diets that were matched for calories. One diet was "morning-loaded", meaning that daily calories were distributed as 45% at breakfast, 35% at lunch, and 20% at dinner. The other was "evening-loaded", with an opposing calorie distribution; i.e., 20% at breakfast, 35% at lunch, and 45% at dinner. The trial received a lot of commentaries online after it was published. However, much of it lacked sufficient context, nuance, and understanding of the implications. In this episode, Dr. Alan Flanagan, who was one of the researchers involved in some of the work of the Big Breakfast Study, gives an insight into the recently published paper by Ruddick-Collins et al., and highlights some important aspects to be aware of. This is an episode exclusive to Sigma Nutrition Premium subscribers. To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium. Links: Subscribe to Premium Links to mentioned studies

In this episode, the Sigma team explores the question: "Do vegan diets increase the risk of depression?" This is a question that emerges from a few different places. First, it's common to hear such a claim from proponents of largely animal-based diets. Some reference is often made about how vegan diets can, at best, worsen symptoms or, at worst, even cause depression. Or conversely, they may state that moving away from a plant-based diet will improve mental health outcomes, including depression. And while all of those specific claims aren't within the scope of this episode, such claims do get people wondering if a plant-exclusive diet is actually a cause of various mental health ailments. But is there a basis for such claims? In this episode, we explore the evidence from two ends: 1) research related to the proposed mechanisms by which a vegan diet could cause problems, and 2) outcome data looking at the impact of such diets. Links: Subscribe to Premium Episode notes page Live event: London, UK (early bird ends Dec 19)