Sigma Nutrition Radio

Links: Go to episode page Subscribe to PREMIUM Receive Danny's weekly email Twitter: @NutritionDanny Instagram: @dannylennon_sigma About This Episode: Note: This is a Premium-exclusive episode, so in order to listen to the full episode you'll need to subscribe to Sigma Nutrition Premium. Low-carbohydrate diets come with a list of reported benefits, and research does show benefit for a number of different outcomes. However, many influencers and advocates of low-carb diets routinely add commentary that is misleading, incorrect, and possibly dangerous. This has led to us highlighting such incorrect information on this podcast before and pushing back against central claims of the "big names" in the "low-carb community". However, low-carbohydrate diets can indeed be a viable dietary pattern for people who wish to consume a healthy diet… provided they meet a few criteria. In other words, it is possible to consume a low-carb diet that still largely fits in with the evidence we have on healthy dietary patterns. In this episode, Danny discusses what health outcomes may result from low-carb diets, and what distinguishes a "healthy low-carb diet" from an "unhealthy low-carb diet". This includes some pragmatic tips for nutritionists, health professionals and consumers, who are choosing to use a low-carbohydrate diet.

Links: Episode page with resources Subscribe to PREMIUM MASS Research Review About This Episode: Metabolic adaptation refers to the process by which the body adjusts its metabolism in response to changes in energy intake or body mass. This adjustment can occur in both directions, meaning that the body can increase or decrease its energy expenditure in response to changes in energy intake or body weight. When someone consumes fewer calories than their body requires for energy, the body will respond by slowing down its metabolism to conserve energy. This can make it harder to lose weight and maintain weight loss over time. Conversely, when someone consumes more calories than their body needs, the body will increase its metabolic rate in order to burn off the excess energy. There are several open debates in science about metabolic adaptation, including the actual magnitude of it, its relevance to weight loss, what measurement methods should be used, and the mechanisms underlying the contributory factors. Some people have framed metabolic adaptation as so significant that it makes weight loss attempts futile. While others, including in research, have referred to metabolic adaptation as an "illusion". So what do we actually know about this concept and what is the pragmatic significance of it? To discuss the nuances of the topic, Alan and Danny are joined by Dr. Eric Trexler, who has published on this topic and has followed recent publications closely. About The Guest: Dr. Eric Trexler is Director of Education at Stronger By Science, where he co-hosts the SBS podcast. He also is one of the four contributors to the MASS Research Review. Eric has a prolific background in exercise science research, with more than 30 publications to his name by the time he completed his PhD at UNC-Chapel Hill. --- Subscribe to PREMIUM

Links: Episode page (with links to studies mentioned) Subscribe to PREMIUM Receive Danny's free weekly email About This Episode: The benefits of consuming a higher fiber diet have been consistently demonstrated in nutrition research. Epidemiology clearly shows that higher intakes, compared to lower intakes, leads to a risk reduction for a range of diseases, including cardiovascular disease and colon cancer. And based on this epidemiological evidence, most dietary guidelines recommend dietary patterns that provide adults with 30-35g of dietary fiber per day. However, what do we know about intakes beyond this? Do we continue to see benefit in a linear fashion? Is there a ceiling to benefit? At what level would we see "optimal" benefit or the greatest magnitude of risk reduction? The ability to answer such questions is hampered by the fact it's difficult to find cohort studies where the "high" fiber level is high enough to relate to this issue. However, there have been some controlled studies looking specifically at "very high" intakes, i.e. those far above current recommendations. In addition, there are some populations where habitual dietary intake gives a fiber intake far above the typcial intakes in Western cohorts. So in this episode we go through this data to try to see what we can conclude about this fascinating question of 'what are the health effects at very high fiber intakes?' New to Sigma Nutrition? Learn more about us here.

Links: Go to episode page (with resources) Subscribe to PREMIUM Receive Danny's weekly email About This Episode: In the last couple of decades, carbohydrates have experienced an increasing amount of negative campaigning. In general, the main argument is that carbohydrates have been viewed as the root cause for obesity, diabetes and several other diseases including heart disease and behavioral disorders. However, there can often be a lack of appreciation that not all carbohydrates are equal in their health effects. Beyond this, now there has even been confusion as to whether high fiber diets with whole grains are good for you or bad. This is mostly a result of strong claims made by people with large online followings and promoting specific diets. What does the best evidence tell us about different carbohydrate types and impacts on health outcomes? Should carbohydrates be viewed as inherently harmful? How solid is the evidence on whole grains, legumes and other high-fiber carbohydrate-rich foods? To help us tease through the science in this area, in this episode we get some answers from nutrition epidemiologist, Dr. Andrew Reynolds. About the Guest: Dr. Andrew Reynolds is a nutrition epidemiologist working with achievable lifestyle and environment change in the prevention and management of non-communicable diseases, such as type 2 diabetes and cardiovascular disease. He primarily conducts randomised controlled trials and meta-analyses. Much of his work is to inform evidence-based dietary or clinical guidelines, policy, and food reformulation. Links: Go to episode page (with resources) Subscribe to PREMIUM Receive Danny's weekly email

Links: Go to episode page (with resources) Subscribe to PREMIUM Receive Danny's free weekly email About This Episode: "Personalized nutrition" has been promoted as an approach that will improve people's health by prescribing them specific dietary recommendations based on their own genetic and phenotypic data. The premise is that given we each respond differently to foods, having general dietary recommendations may be doing many people a disservice. And by using an array of personal data, it is now possible to give unique diets that improve health. The early and interesting findings of research in this area was met with much fanfare, and indeed, many companies are now offering commercial direct-to-consumer services based on genetic and physiological testing, followed by "personalized" dietary prescription. Such testing may include genetic tests, microbiome testing, glucose monitoring data, and more. This data is then fed into machine learning algorithms to prescribe dietary recommendations. However, do the marketing claims match the current evidence? Does the "proof" it works that is often cited, actually back up the claims? Do personalized nutrition diets actually lead to improved health outcomes over generic, conventional dietary recommendations? Do personalized nutrition diets lead to better outcomes than standard dietetic/nutrition practice? To answer these questions, we go through the main studies cited in favor of personalized nutrition being superior to typical dietary advice, and see if they indeed support the claims. So is personalized nutrition superior to standard dietary advice? Let's find out… Note: This is a Premium-exclusive episode, so in order to listen to the full episode you'll need to subscribe to Sigma Nutrition Premium. However, you can listen to a preview here.

Links: Go to episode page (with further resources) Subscribe to PREMIUM Get Danny's weekly email, the Sigma Synopsis About This Episode: While it has long been acknowledged that high intakes of saturated fat can increase risk of atherosclerotic cardiovascular disease due to their impact on blood lipids, there are some who question the association between saturated fat and heart disease. Specifically, they may state that the evidence for this association is weak or non-existent, typically by pointing to some commonly cited studies that show null associations between saturated fat and CVD outcomes. On this basis, they may conclude that there is no basis to aim to limit saturated fat intake to current recommended levels or that reducing saturated fat intake will not actually improve health outcomes. In this episode, Alan and Danny look at the four most commonly cited publications showing a null association, highlighting some key issues. Beyond that, they look at a number of other lines of evidence on saturated fat that allows one to come to a confident answer on this question. So does reducing saturated fat intake to recommended levels actually reduce heart disease risk? Let's discuss…

Links: Go to episode page (with resources) Subscribe to Sigma Nutrition PREMIUM Receive Danny's free weekly emails About this Episode: The beneficial impact of a high-fiber diet is something that has been promoted in nutrition for a long period of time. But there remain a variety of interesting questions to researchers, practitioners and the general public alike. How much fiber do we actually need? What are current fiber recommendations based on? What outcomes have the strongest evidence for benefit? Should we have targets for fiber sub-types? Are some types of fiber "better" than others? Do functional fibers added to food products still retain the benefits we see with dietary fiber? To help get to some evidence-based answers on these issues, our guest in this episode is one of the researchers at the forefront of dietary fiber research for decades, Professor Joanne Slavin.

Links: Go to episode page Subscribe to PREMIUM Receive Danny's free weekly email Description: Blood glucose responses play a crucial role in maintaining good health, and any abnormalities in glucose regulation can lead to several chronic conditions. Diabetes is one such disease that results from a lack of insulin production or the body's inability to use insulin effectively, leading to elevated blood glucose levels. There has been debate about what exactly constitues a "healthy" and "unhealthy" blood glucose response. While it is suggested that unhealthy blood glucose responses are characterized by erratic and unpredictable "spikes" in blood glucose levels, sometimes vague terminology leads to people worrying about normal blood glucose responses. This may be particularly related to the increasing prevalence of continuous glucose monitoring (CGM) devices that allow individuals to track their glucose levels in real-time. While these devices can be helpful for people with diabetes to manage their glucose levels, they can also lead to unnecessary concern and anxiety about small, normal glucose elevations. In recent years exciting advances have been made in diabetes remission research. And off the back of that, more research has looked at various dietary interventions that could either directly impact remission, or act as an adjuct to other interventions. In this discussion with Dr. Nicola Guess, we discuss a range of topics related to glycemia, diabetes, and diet. This includes the potential for high-protein interventions, what utility CGMs actually have, what to make of diabetes remission trials, and future directions for the field.

Links: Go to episode page (w/ resources) Get Danny's weekly emails Subscibe to Premium Description: Understanding the concept of an "exposure" is a critical aspect to nutrition science literacy. The 'exposure of interest' refers to the variable or factor that is being studied to determine its relationship with a particular health outcome. For example, in a study examining the relationship between diet and heart disease, the exposure of interest may be a particular nutrient or food group, such as saturated fat or red meat consumption. But when reading research we need to be able to critically examine the levels of an exposure and ask were these suitable for the research question at hand. For example, is there a sufficiently wide contrast in the exposure between the groups being compared? How do the reported levels of intake relate to what we know about this exposure from the wider literature? Much has been made of the many 'null' associations found in nutrition epidemiology. But in many cases, these may be accounted for by looking at the exposure contrast or absolute intakes in those studies. Something we referred to as "null by design". In this episode, Danny and Alan go through the most crucial aspects to understand about the exposure of interest in nutrition, hopefully leading to an enhanced understanding of interpreting nutrition research.

Links: Episode page with related links Subscribe to Sigma Nutrition Premium Receive Danny's free weekly email Description: Substantial evidence shows that a high intake of saturated fat in the diet has the potential to significantly raise LDL-C and ApoB-containing lipoproteins in many people, and in turn increase their risk of developing atherosclerotic cardiovascular disease (ASCVD). However, people may raise what seems to some contradictory evidence, or what is sometimes thought of as a paradox: the impact of full-fat dairy on CVD risk. This paradox arises because given the saturated fat content of full-fat milk, yogurt and cheese, we typically don't see the same impact on blood lipid profiles. In addition, epidemiology can often show such foods in a favourable light. And the dairy fat story gets more interesting when we look at evidence showing there is a huge difference in the impact of consuming different dairy foods (e.g. butter vs cheese/yogurt). So this leads to many questions that people rightly ask, which we aim to address in this episode. Questions such as: Why doesn't increased dairy consumption lead to same increases in CVD risk as other saturated fat sources? Do results from full-fat dairy studies prove that saturated fat isn't a problem? What is it about cheese/yogurt that makes it different to butter? How do low-fat and full-fat dairy compare? Diets including/excluding dairy: how to compare? Subscribe to Sigma Nutrition Premium

Links: Go to episode page (with resources) Subscribe to Sigma Nutrition Premium Receive our free weekly emails Introduction: Discordance between low-density lipoprotein particle (LDL-p) and low-density lipoprotein cholesterol (LDL-C) occurs when the levels of these two biomarkers do not match up as expected. Discordance between Apolipoprotein B (ApoB) and low-density lipoprotein cholesterol (LDL-C) is similar, except rather than counting just LDL particles, ApoB is a measure of the numbers of lipoproteins that have an ApoB attached. Discordance between ApoB and LDL-C can lead to either an underestimate or overestimate of ASCVD risk. And therefore there may be important implications for someone who does have discordance. Additionally, it is such cases that suggest that a measurement of ApoB may provide additional information beyond traditional lipid measures in assessing a person's cardiovascular risk. Recent work from researchers at Liverpool John Moores University has investigated whether discordance is associated with certain dietary patterns. In this episode, one of the researchers involved, Dr. Ian Davies, is on the podcast to discuss this work in addition to wider questions in the diet-lipids-CVD field that remain to be answered.

Links: Go to episode page (w/ resources) Subscribe to PREMIUM Receive Danny's free weekly email Description: Fructose is a type of sugar that is commonly found in fruits, vegetables, and many processed foods. In recent years, there has been a lot of discussion and debate about the impact of fructose on health, with some claiming that it is a major contributor to obesity, diabetes, and other chronic diseases. However, these claims are often at odds with what the scientific literature actually says. One of the most common claims about fructose is that it is inherently "bad" for health, and that consuming too much of it can lead to a wide range of health problems. This idea has been popularized in many popular diet and health books, and has led to a widespread fear of fructose among the general public. However, many of these claims are based on outdated or oversimplified research, and do not reflect the complex reality of how fructose interacts with the human body. Another common claim about fructose is that it is uniquely responsible for the current obesity epidemic, and that reducing fructose intake is the key to weight loss and better health. While it is true that excessive consumption of sugary foods and beverages can contribute to weight gain and other health problems, the idea that fructose is uniquely responsible for these issues is not supported by the scientific evidence. In fact, many studies have found that total sugar intake, rather than fructose specifically, is the most important factor in the development of obesity and related health problems. In this episode we discuss the unique aspects of fructose metabolism, why some studies appear to show unique harm of fructose, and the implications of this for dietary choices. Go to episode page

Links: Go to episode page Subscribe to Premium Sign-up for our free weekly email: The Sigma Synopsis Description: The idea of food addiction has gained a lot of attention in recent years, as obesity rates continue to rise around the world. Many people struggle with overeating and find it difficult to resist certain foods, leading to a cycle of guilt and shame. The concept of food addiction suggests that there may be a biological explanation for this behavior, and that certain foods may be especially "rewarding" to the brain, leading to a kind of addiction. To help look at the evidence in this area, our guest in this episode is Dr. Charlotte Hardman, who is a leading researcher in the field of appetite and obesity. Dr. Hardman's research focuses on the psychological and biological processes that contribute to overeating and obesity. She is particularly interested in the concept of "food addiction," which suggests that certain foods may be addictive and lead to compulsive overeating, similar to substance addiction. In this podcast, we will explore the latest research on food addiction with Dr. Hardman. We will delve into the evidence for and against the idea of food addiction, as well as discuss the potential implications for public health and policy. Join us as we explore this fascinating topic and learn more about the complex relationship between food and the brain.

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

The endocrine system plays a central role in growth, development, metabolism, reproduction, and physical well-being throughout life. Hormones interact in complex networks, orchestrating a range of critical functions. Over the life course, we experience various changes in hormone levels, fluctuations, patterns, and actions. Additionally, lifestyle factors and disease processes can impact the levels and functions of hormones. In this episode, Dr. Nicky Keay, a medical doctor with expertise in the field of exercise endocrinology, is on the podcast to discuss a variety of endocrine-related issues, including: hormone diurnal variation, bone health, amenorrhoea, HRT, perimenopause, and thinking about hormones and aging. Links: Episode page Subscribe to Premium Sigma live event in Berlin Sigma recommended resources

Stable isotopes have been used as tracers in human nutritional studies for many years. But what are they? Why do we use 'tracers' in nutrition studies? And what are some practical examples? A chemical element can have different forms or 'isotopes.' These different isotopes have the same atomic number and position in the periodic table but have different atomic masses and physical properties. An isotope that is not radioactive is said to be 'stable'. In physiology and metabolism research, stable isotopes are used as 'tracers.' As the name implies, it allows us to 'trace' the fate of compounds, thus giving a very detailed insight into the metabolism of nutrients and the regulation of many disease processes. In this episode, Dr. Alan Flanagan explains what stable isotope tracers are, how they are used to answer nutrition science questions and some examples that you may come across. This is a 'Nutrition Science Explained' episode. These episodes are exclusive to Sigma Nutrition Premium. To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium.

Given the negative consequences of consistent overconsumption of food (leading to a caloric surplus), having a dietary intake that is of appropriate calorie intake is an important aspect of long-term health. Therefore, thinking about which foods and diets can help promote appropriate satiety to keep calorie intake in check is a key focus for many researchers and practitioners. There is a complex system of human appetite control. This appetite system influences food consumption and associated motivational drives such as hunger, as well as interacting with and being influenced by energy expenditure. Satiety is an important psycho-biological process involved in the expression of human appetite, inhibiting hunger and intake following food or beverage consumption. In this episode, the Sigma team discusses the human appetite system, how different nutrients and foods impact satiety, and the implications of this research. Links: Subscribe to Premium Show notes for this episode Live event in Berlin, Germany Sigma Recommended Resources

Hypertension (elevated blood pressure) is a condition that significantly increases the risk of several diseases and is a major cause of premature death worldwide. In the US, recent estimates suggest that about half of the adult population has hypertension. At a population level, high sodium intake is one of the main dietary risk factors. All population health guidelines recommend keeping sodium intake below certain levels. While, on average, blood pressure correlates with sodium intake, there is a wide range of responses on an individual level. People who see increasing sodium intake lead to increased blood pressure are termed "salt sensitive". Others, however, don't see much change in blood pressure with increased dietary sodium. Such individuals are classed as "salt resistant". In this episode, Assistant Professor at Auburn University, Dr. Austin Robinson, is on to discuss whether people who are salt resistant need to keep their sodium intake low or not. And other individual and group differences that exist for hypertension risk and sodium physiology? Links: Subscribe to Premium Episode overview Live event in Berlin Recommended Resources

Exercise improves metabolic control both via increasing muscle glucose uptake during muscle contractions by insulin-independent mechanisms and by increasing skeletal muscle insulin sensitivity after physical activity. A reduction in skeletal muscle insulin sensitivity is an early event in the development of not only prediabetes, metabolic syndrome, and type 2 diabetes but is also associated with other conditions such as cardiovascular disease and some cancers. One of the researchers that has been at the forefront of research in this area for many years is Professor Glenn McConell. In this episode we discuss glucose uptake during and after exercise, looking at both insulin-dependent and insulin-independent mechanisms. In addition we discuss the crucial importance of muscle insulin sensitivity and some important research breakthroughs on the topic. Links: Subscribe to Premium Episode show notes Live event: Berlin

The term 'tactical populations' has been applied to those working in law enforcement, fire, first responders, and military. In addition to the importance of their work, the work they do itself presents some challenges for health and nutrition. Despite the fact that such individuals make up a significant number of the population and their work plays a crucial role in society, there is currently very little research on fire and law enforcement nutrition. Most research is on the prevalence of disease and the occupational risk factors and related pathophysiology. Lifestyle research, descriptive and interventions, is way behind. Dr. Jill Joyce is the co-director of the OSU Tactical Fitness and Nutrition Lab at Oklahoma State University. She does research looking at real-world interventions in these populations, particularly firefighters, in an attempt to improve their diets and health. In this episode, we look at both the theoretical and pragmatic realities of improving diet and health in firefighters and some other tactical populations. Links: Subscribe to Premium Access show notes Live event in Berlin

In this Premium-exclusive 'Ask Me Anything' episode, Alan & Danny answer a range of listener questions. Topics include obesity rates, lowering blood pressure, cholesterol drugs, PCOS, and what issues they have changed their minds on. See the full list of questions below. [02.37] Do you feel that there is hope (or an effective way forward) for obesity rates to come down? Based on your response, why/why not? [11.28] In this field, it seems like so many of us have had positions we've held very seriously that we now see as poorly supported by research, or just have a significant paradigm change. It would be great to hear you look back to how your views have evolved over the years. [30.34] Apart from lowering salt intake and eating foods high in potassium are there other things you can take or do to reduce blood pressure? [40.34] What is the best ratio of DHA vs EPA to increase my Omega 3 index? [46.20] Statins v Ezetimibe: Differences between the two? Mechanism of action? Are there situations, conditions, genetic markers where one may work better than the other? [56.20] I'm starting a PhD in the fall concerning the pathophysiology of metabolic diseases and I'd like to take some courses that would help me in my research. Would you have any recommendations for a beginner scientist? [59.01] Is astaxanthin a good substitute for algae oil for someone who follows a vegan diet? [60.45] Do you have any suggestions how to better manage hunger in obese women with PCOS? [64.33] Do you have any recommendations for anyone wanting to get involved in chrononutrition research? Links: Subscribe to Premium Live Event: Berlin, Germany on November 26th 2022 Episode transcript Resources mentioned in this episode

When it comes to eating to promote muscle hypertrophy, muscle repair/recovery and maintenance of mass and function, protein has been an obvious focus. Indeed muscle mass and quality are dependent on the continuous remodeling of skeletal muscle proteins. This is related to the amount of muscle protein balance, i.e. the net difference between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Because of this, MPS has long been used as a proxy measure for muscle repair and/or growth of muscle. Protein feeding increases MPS, with the amino acid leucine having a specifically strong impact on MPS. Therefore both the dose of protein and the amino acid profile of the protein have been looked at to assess which protein sources are "superior" for muscle mass and function. This has typically led to viewing animal proteins as better than plant proteins. But many assumptions are layered into conversations on the topic. In this episode we explore some important points that are often neglected. Is MPS as reliable as we assume? Does the amino acid profile tell us everything about the anabolic effect of a protein? Does dose and timing matter as much as we think? How does the picture change when we look at whole foods or mixed meals? Link: Subscribe to Premium Go to show notes Live Event: Berlin, Germany MASS Research Review Muscle & Strength Pyramids: Training & Nutrition Books

The brain plays a central role in both physical and psychological function and performance. The brain also has a very high energy demand. In addition, fatiguing conditions can cause impairment of cognitive performance. One area of research in neurometabolism related to the potential use of nutrients on improving cognitive function, as well as "rescuing" the fatigue-related declines in performance. Nick Gant is Director of the Exercise Neurometabolism Laboratory at the University of Auckland. His group uses interdisciplinary approaches from the nutritional sciences and neurosciences to investigate the role of nutrition in brain health and performance. Nick is particularly interested in foods and supplements that prevent brain fatigue and improve physical and cognitive function. Subscribe to PREMIUM

This episode was oringally published as one of our "Expert – ask me anything" (AMA) episodes, which we published for Premium prescribers. In such bonus episodes, we collect questions from Premium subscribers and ask them direct to a world-class expert and past podcast guest. If you're interested in subscribing to Sigma Nutrition Premium, then check all the details here. In this episode Prof. Stu Phillips takes questions about synethized whey protein, plant proteins, post-exercise MPS, and many other topics related to protein, muscle function and ageing.

It has been consistently shown in research that elevated dietary sodium consumption is associated with high blood pressure and an increased risk of cardiovascular disease. In addition, low levels of dietary potassium intake are associated with these same risks. However, there is some debate on how to characterize these relationships. In a study published in European Heart Journal in July 2022, using data from the EPIC-Norfolk study, researchers attempted to answer whether the associations between potassium and both blood pressure and cardiovascular disease: 1) differ between men and women? and 2) depend on daily sodium intake. In this episode Dr. Alan Flanagan and Danny Lennon discuss the details of this study and then link it to the overall evidence base and what this may mean for potassium (and sodium) intake considerations. Access show notes Subscribe to Premium

With the advances in understanding the importance of the gut (including its bacterial contents) for human health, much interest and attention has been placed on how to eat to promote positive 'gut health'. This has led to many exciting research questions and labs doing fascinating work. However, on the opposite side, it has led to a spike in opportunistic quacks to jump on the wave of enthusiasm and promote diets, supplements, testing kits and products that don't reflect the current evidence base. So what do we actually know? What aspects of diet should we focus on to improve gut health? For those with gut symptoms (bloating, pain, irritable bowel, etc.) is it possible to include more vegetables and fiber without the pain? In this episode, gut health researcher at King's College London, Dr. Megan Rossi, discusses some simple heuristics to follow that will likely improve overall health, and promote positive gut health. Access show notes here Subscribe to Premium

A study published in March 2022 suggested that consumption of artificial (non-nutritive) sweeteners is associated with a 13% increase in risk of cancer. And so in this episode, Dr. Alan Flanagan, Dr. Niamh Aspell, and Danny Lennon discuss this specific study and give their thoughts on what are fair conclusions to come to. Access show notes here Subscribe to Premium here

While we've never known more about diet and health, there remain many unanswered questions in nutrition science. However, there is often disagreements on how best to answer these questions, particularly in relation to informing practical diet advise that meaningfully improves health. Prof. Norman Temple is one academic who has written on a number of these issues. One issue he highlights is the large discrepency in the practical value we have attained from cohort studies and RCTs, relative to mechanistic research. Another is the limitations of RCTs for nutrition-specific research questions. In this episode, Prof. Temple discusses these issues, as well as what strategies can actually improve population diet, and thus health. Access show notes here Subscribe to Premium here

A recent study reported a higher risk of developing melanoma in people who ate a relatively high intake of fish. This study caused headlines and it was picked up by many outlets (including the New York Times, Sky News, etc.). In this episode, Alan and Danny dig into the nuances of this study to see if the headlines are justified. Click here for show notes Click here for Premium

This is an "ask me anything" (AMA) episode, which means a world-class expert and past podcast guest comes on the podcast to answer questions submitted by you, our podcast listeners. Stephan Guyenet spent 12 years in academia studying neurodegenerative disease and obesity neuroscience. He was a postdoctoral fellow at the Univeristy of Washington, studying the neuroscience of obesity and eating behavior. Previous to that he completed a PhD in neuroscience. Stephan is the author of the popular and well-received book 'The Hungry Brain', which lays out the science behind the brain's role in obesity. To subscribe to Premium (and get the full episode) go here. Questions Answered In Full Episode "When someone undergoes liposuction or other surgery that removes adipose tissue, is there a sudden reduction in leptin levels? While this may reduce leptin resistance, could the drop in leptin lead to increased hunger over time?" "What is the current research around how chronic energy restriction (or following crash diets) affects appetite hormones and/ or appetite regulation long term? Is there a physiological mechanism influencing overeating attributable to appetite dysregulation caused by chronic dieting? I ask as this is something I am often tackling in my nutrition consultancy but research in biochemical and physiological mechanisms seems lacking." "Can you talk about the conditions of anorexia and morbid obesity and how they essentially defy the rules of metabolic compensation? In other words- I understand anorexia to be a mental health condition where the individual starves themselves with a purpose to control weight. And morbid obesity being excessive consumption despite over fatness, etc. If the body has these numerous mechanisms by which calorie restriction or calorie over- consumption results in these compensatory processes-driving us to eat more/less slow us down/speed us up, and many more; do these individuals not "hear" these signals or are they just adept at ignoring them or is it that their bodies have lost the ability to compensate for their under or over consumption? Additionally, can anyone become anorexic or morbidly obese? Or is it merely genetics?" "Why do some SDRIs (serotonin–dopamine reuptake inhibitors) and serotonin precursors reduce hunger/appetite? E.g. 5-HTP and Wellbutrin (Bupropion)" "Question about the ideal weight program: As an iOS developer, my instinct is to assume determinism and quantifiability of the entire universe. I believe this to be fundamentally true. But what is hypothetically possible differs from what we can realistically know. I worry that attempts like yours to quantify some seemingly qualitative measures are doomed. I have similar concerns about happiness research. How do you reassure yourself you can really construct an algorithm that deciphers the "ideal weight program" for any given user – do you rely on averages?" a. Quick explanation of the ideal weight program "In 2018 a poster was presented at the annual meeting of the Society for Neuroscience titled 'The human brain microbiome; there are bacteria in our brains!' which showed bacteria apparently penetrating and inhabiting the cells of healthy human brains. While the work was preliminary, have you heard of any further work in this area? What is your opinion on the possibility that, if bacteria do inhabit the brain, they could play a part in appetite regulation and/or obesity similar to how the gut microbiome can affect our health?" "It seems like there are significant differences in policies put forth between researchers from biomedical backgrounds and ones from public health policy backgrounds. Dr [David] Allison touched on this during recent interviews, noting that there is very little evidence regarding the efficacy of upstream obesity prevention interventions, such community gardens, combatting food deserts, nutrition education, and cooking classes. On the other hand, governments are increasingly turning to such interventions, as well as policies such as front of pack labelling (Canada, 2022), nutrition facts tables, calorie labelling on menus, as well as the aforementioned ones. Given your research on determinants of health and obesity, what are some of the most promising interventions to prevent NCD morbidity, as well as stones unturned in public health policy? Would you agree with individuals such as Dr Allison that in our current environment, the only efficacious interventions are drugs and bariatric surgery?" Question based on your debate on JRE with Gary Taubes: "Would the insulinogenic effect of protein, specifically something like whey protein which causes an insulin response, be something that should automatically refute Taubes arguments about insulins inherent role in increasing adiposity? Second, would overeating on any macronutrient increase insulin simply because you are eating more food (i.e. hypercaloric)?" "Are there best practices for the maximum duration someone should spend in fat loss (or wei

Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, such as through variations in the solar cycle. But since the 1800's, human activities have been the main driver of climate change, primarily due to burning fossil fuels like coal, oil and gas. Climate change has the potential to negatively impact the nutrient value of plants, soil organisms, food stuffs, via a variety of ways. Climate change puts food supplies at risk. Floods, droughts, more intense hurricanes, heatwaves and wildfires can drive down crop yields, destroy livestock, and interfere with the transport of food. And rising carbon dioxide levels from human activity can make staple crops like rice and wheat less nutritious. In this podcast the Sigma team take a look at the evidence on how climate change will impact nutrient status, if left unchecked. There will be also a look at what solutions have been put forward to tackle this issue. This episode will focus more on how climate change impacts nutritional & nutrient status, as opposed to converse (but equally important) issue of how food systems impact climate change. Access show notes here Subscribe to Premium here Attend a live event in London, Dublin or Berlin!