Sigma Nutrition Radio

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)

Gyorgy Scrinis, an expert on ultra-processed foods and their effects on nutrition and food systems, dives deep into the complexities of our modern diets. He discusses the Nova food processing classification system and its implications for health, advocating for a holistic understanding beyond mere nutrients. The conversation highlights the socioeconomic factors driving the rise of ultra-processed foods, particularly in disadvantaged communities. Scrinis emphasizes the need for systemic changes in public policy to tackle food poverty and inequality, making it clear that nutrition is intricately linked to broader social issues.

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

The podcast explores the alarming trend of undermining true expertise in nutrition. It discusses how influential online voices often lack genuine knowledge, complicating the landscape for those seeking reliable health information. The hosts emphasize the importance of domain-specific expertise, warning against oversimplified critiques of complex nutritional studies. They also highlight the dangers of entertainment-focused platforms as sources of health information, stressing the need for informed decision-making in the digital age.

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

Dr. Nicky Keay discusses hormone diurnal variation, bone health, amenorrhea, HRT, perimenopause, and aging implications in the context of the endocrine system across different life stages. The intricacies of hormones, importance of timing in hormone testing, and maintaining hormonal balance through lifestyle interventions are emphasized.