Sigma Nutrition Radio
Sigma Nutrition Radio
About Sigma Nutrition Radio
Discussions about the science of nutrition, dietetics and health. The podcast that educates through nuanced conversations, exploring evidence and cultivating critical thinking. Hosted by Danny Lennon.
Questions Answered in this AMA [00:03:01] Mechanisms that keeps weight stable over time? [00:11:52] Semaglutide: Game-changer? Weight regain? [00:30:42] How to further lower LDL-C? Can I avoid statins? [00:43:52] Glyphosate: A cause for concern in food? [00:48:30] High caffeine intake is making me sweat more. What’s going on? [00:55:16] Should I avoid non-organic meat? [01:00:08] Is there evidence on iron and zinc co-ingestion for anemia of prematurity? [01:03:09] “Carni-nutrients”: Can vegan diets cause brain issues due to lower choline, creatine and taurine? [01:12:10] Are energy drinks bad for us? [01:17:43] What are some resources for doctors and patients that simply explain obesity & treatments? This is an episode exclusive to Premium subscribers. To listen to the full episode you’ll need to subscribe. However, you can listen to a preview here.
Links: Go to episode page (with links & resources) Subscribe to Sigma Nutrition Premium Receive our free weekly email, The Sigma Synopsis About This Episode: Often claims are made recommending that people should aim to keep peaks in blood glucose low in terms of both magnitude and frequency. And while many claims about blood glucose “spikes” are incorrect or purposefully exaggerated to grab attention, there are some reasonable and interesting hypotheses put forward in relation to blood glucose variability and excursions. For example, interesting questions have been raised in relation to the impact of blood glucose excursions in seemingly normoglycemic and/or healthy people. In this episode, we look at three specific elements of this: average blood glucose, glucose variability, and glucose peaks. All in the context of people without prediabetes or type diabetes, who have typical blood glucose measures in the ‘normal’ range. Specifically, we look at three hypothesized recommendations made elsewhere: “The lower you average blood glucose (HbA1C) is better, even if already in normal range” “The more you can minimize glucose variability, the better.” “Minimizing the number of glucose “peaks” is important, even if they don’t meet the threshold for hyperglycemia” Can normoglycemic people benefit from further reducing these measures? Let’s take a look…
Links: Episode page (with more links) Subscribe to Premium Introduction Depression is a common disorder and is a leading cause of disability worldwide. Depression results from a complex interaction of social, psychological, and biological factors. Diet has been one area that has been suggested in playing a role; from potential for exacerbating symptoms to being a treatment. And while some associations have been noted, many claims far exceed what (little) evidence exists. Online it is common to see people claiming certain diets can treat depression or that certain foods will improve outcomes. However, does the evidence match such claims? In trials that have been published on diet-depression, there has been considerable media attention and fanfare around some results. For example, the SMILES trial published out of Australia. However, some have raised considerable concerns about the interpretation of such findings. In this episode, clinical psychologist Dr. Nicole Lippman-Barile is on the podcast to discuss what we currently know about diet and depression, what issues exist with current studies, and why many nutrition-mental health studies are being incorrently interpreted.
Links: Subscribe to Premium Go to this episode's page (with links) Live event: London - March 18th Receive 'Sigma Synopsis' emails Description: When thinking about the effect of eating or not eating a certain food or nutrient, we can’t consider this in isolation. Meaning, we need to evaluate the impact within the context of what such an inclusion/exclusion does to an individual’s overall diet pattern. Thinking about this concept, the phrase “compared to what?” has been colloquially used. And while this is an important idea, there has been some misapplication of this principle. In nutrition science, this is related to the concept of food or nutrient “substitution”. And this concept is crucial to understanding the issues that can arise in nutrition studies, particularly when it comes to single food analyses in nutritional epidemiology. This concept of substitution is quite intuitive in controlled feeding studies. However, it is not as obvious when considering nutrition epidemiology studies. As noted by Ibsen & Dahm (2022): “Whereas studying the effects of eating one food instead of another is typically explicit in interventional study designs, it is often implicit and sometimes hidden in analyses of observational studies.” However, in nutrition epidemiology substitution is still happening, but it typically emerges as a consequence of adjustment models. In nutritional epidemiology, it is essential to adjust for confounders. E.g., one vital adjustment is often for total calorie intake. However, when our exposure is a specific food/nutrient, we must think about confounding by other foods. So knowing what, and how, a study is adjusting for variables helps us interpret it better. In this episode, Dr. Alan Flanagan and Danny Lennon discuss these crucial ideas of food substitution, adjustment models, and “compared to what?”. Go to this episode's page (with links)
Links: Episode page Subscribe to Premium Live Event: London, UK Receive the Sigma Synopsis emails About This Episode: Does sodium lead to calcium losses? Do high-salt diets harm bone health? At what thresholds could there be an impact? Does any of this change our recommendations around salt/sodium intake? Thanks to Sigma Nutrition Premium subscriber Kate Wall for submitting a question in the member’s area that inspired this episode. Kate asks: “Salt can impact calcium excretion in the urine and it is said that a high salt diet can increase risk of osteoporosis as it draws calcium from the bone and excretes it. How much of an impact does dietary salt intake actually have on bone health and how high would salt intake have to be for this to be a concern? Obviously high salt intakes are not something to aim for in general, but just wondered if this was a mechanism that could remove meaningful amounts of calcium in a way that I should be advising around this in those that we work with as nutritional professionals. Thanks!” So in this episode, Danny and Alan look at some of the evidence in this area to see if there are impacts that have pragmatic implications for nutrition and medical professionals, as well as health-concious people.
Links: Subscribe to Premium Episode page Description: Nutritionists, dietitians and other health & fitness professionals face many challenges when attempting to help their clients and in understanding what approaches are best in a given situations. There are often discussions around improving client adherence to dietary recommendations. However, sometimes we need to think deeper about this topic. Is there really just a tool to fix this? Or could the problem be the recommendations themselves? Similarly, while quantifying dietary intake in terms of calorie and macronutrient amounts can be useful in some cases, it’s clear that this isn’t the best approach in many cases. So for coaches aiming to help athletes or those with body composition goals, how do we use “non-tracking” approaches effectively? This episode brings you a roundtable discusssion between three accomplised and insightful nutrition professionals; Dr. Eric Helms, Dr. Zoya Huschtscha, and Mackenzie Baker. In the episode we discuss the above-mentioned topics and more.
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)
Links: Show notes page (incl. study links & related episodes) Subscribe to Sigma Nutrition Premium Live event in London, UK About this episode: Over the past decade, the increasing uptake and acceptance of the Nova food processing classification system has placed focus on one of the categories in Nova; ultra-processed foods (UPFs). Ultra-processed foods (UPFs) are products created from deconstructed (and recombined) food components, usually with the goal of creating a highly palatable, convenient, and profitable product. This typically means such products are high in nutrients of content (e.g. sugar, sodium, saturated fat, etc.). But in addition, they have other characteristics that may make them detrimental to health, particularly when they replace unprocessed or minimally processed foods in the diet. There is now clear evidence showing that when such products make up a large proportion of the diet, such a dietary pattern has negative health effects. However, there are still many unanswered questions and many debates within nutrition science about how to best classify UPFs, to what degree they need to be limited, whether some can be beneficial, and what to do with policy going forward. To offer one perspective on this issue, Associate Professor of Food Politics and Policy at the University of Melbourne, Dr. Gyorgy Scrinis, is on the podcast to discuss his work in the area. While we have discussed the problem of reductionism in nutrition science previously on the podcast, Dr. Scrinis’ use of the term ‘reductionism’ does differ a bit from the way others use the term. For example, he suggests that nutrition science has been too reductive even at the food-level and dietary-pattern level. His work on ultra-processed foods and the Nova classification system has attempted to understand the technological and corporate character of ultra-processed foods, the power of food corporations, and how food corporations shape and capture nutrition science for the purposes of promoting and defending their products.
Research has shown that food marketing strongly impacts children’s eating behaviour. Marketing influences food purchase requests, purchases, and preferences. And the evidence of a relationship between food marketing exposure and obesity meets epidemiological criteria for causality. The evidence suggests that the impact of food marketing is a function of both exposure to the marketing message and its persuasive power. What does the current evidence tell us about the exact effect of marketing on food choices? And beyond that, what strategies are likely to yield the best results in terms of mitigating the harms of food marketing on eating behaviour, particularly in children and adolescents? To help answer these questions, subject area expert Prof. Emma Boyland is on the podcast to discuss what is currently known. Links: Episode page, resources & links Subscribe to Premium
Never before has there been greater access to information about nutrition and health. But never before has there been such a low barrier to being seen as an “expert”. There are large numbers of people getting information from, and basing their health decisions on, people who don’t have direct expertise in the field in which they are talking about. Moreover, some promote the lack of domain expertise as a feature, not a bug. They claim that those that were conventionally seen as domain experts are either brainwashed, lazy in their thinking, or outright corrupt. And the solution is instead to look to those with a fresh perspective that can illuminate us on the “truth”. In this episode, Alan and Danny discuss this “death of domain expertise”, how it plays out online, and its ramifications for people’s ability to get good information. This is a Premium-exclusive episode. To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium. Links: Episode page Subscribe to Premium
Obesity increases the risk of a range of chronic diseases and negative health outcomes. And trials where a sufficient amount of weight loss is achieved show health improvements. However, despite the “straightforward” nature of causing weight loss through a hypocaloric diet, it is clear that most people who lose weight will regain some or all of the weight. This is a result of both the physiologic control of intake and expenditure (i.e. homeostatic regulation by the body to avoid staying at a lower body or fat mass), and environmental factors. Diet-induced weight loss is followed by a number of hormonal change that encourage weight regain. So how do we tackle this problem? In this episode, Dr. Priya Sumithran discusses this physiologic control of body mass, in addition to environmental and behavioural factors that make weight loss maintenance difficult. Dr. Sumithran also discusses what this means for setting weight loss targets, choosing the correct intervention, and looking to non-weight-centric approaches for certain individuals. We also discuss the evidence on GLP-1 receptor agonist drugs, such as Semaglutide, as a treatment for obesity. Links: Episode page Subscribe to Premium Sigma live event - Berlin Sigma recommended resources
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