Category Archive

There has been much concern voiced over the years about the potential harms to both human health and the environment of genetically-modified (or more accurately, genetically-engineered) crops. tolerance, and even enhanced nutritional content. But are these advantages possible without harm? In this episode, Alan and Danny discuss the current evidence on genetically engineered crops (or GMOs) and their effect on human health, biodiversity, and the economy.

One propsed intervention for increasing longevity and/or healthspan is fasting. But what does the current evidence tell us? Does the evidence actually match the hype? In this episode Dr. Niamh Aspell, Alan Flanagan and Danny Lennon discuss some of the data on fasting and longevity.

While dietary guidelines universally include fish as a food group that can be consumed regularly in a healthy dietary pattern, there are some potential risks of fish consumption that get raised. Some have some legitimacy, for example the frequency of consumption of high-mercury fish. However, other claims can go to extremes (“eating fish is bad for you”) that are based in ideology rather than evidence.

In this Quack Asylum episode, we use a video made by a medical doctor as an example of where quackery can raise its head on this topic. Specifically, there are four claims made in the video that we investigate and see if there is any basis to them.

There is now widespread use of various “artificial sweeteners” in foods and beverages. Most commonly non-nutritive sweeteners are used to sweeten a products, whilst having less sugar and calories than a traditionally sugar-sweetened version of that product. For example, diet drinks (e.g. diet soda) are most commonly associated with artificial sweeteners. However, they are also in a wide variety of food products and supplements.
For a long-time there has been skepticism and alarm raised about their potential health effects. From claims of them increasing our food intake, all the way to causing cancer. And food safety authorities have conducted rigorous examinations of the safety data on each of these compounds.
In this episode, the Sigma team discuss the initial research that raised alarm bells, the current process of safety evaluation for non-nutritive sweeteners, the amounts they are consumed in, and the studies published thus far examining their health impacts.

In this episode we address the idea that you shouldn’t eat vegetables, or that they aren’t beneficial. We will specifically look at a number of claims that relate to: 1) The claim that vegetables aren’t beneficial for health, or that there is no health benefit to high vegetable intake; 2) The claim that vegetables are actually detrimental to health, and their removal improves health.

The popularity of soy foods and soy-based products has been increasing in recent times. This has been particularly the case as a dairy alternative, with people switching to using soy ‘milk’ and soy-based yogurts and cheese. Additionally, soy has become popular as a meat alternative in a variety of dishes for those looking to reduce meat intake. Soy foods such as tofu can be used in recipes in place of meat, and soy-based ‘meat alternatives’ that are vegetarian and vegan friendly have been developed.
With this increased prevalence, there has been some debate about the health effects of consuming soy foods and products. On one side, there have potential benefits highlighted of inclusion of soy in the diet. It contains phytoestrogens, which may have beneficial effects. Additionally, it is low in saturated fat, and so is potentially beneficial when used in place of saturated fat-rich foods. However, some have claimed that the phytoestrogens (isoflavones specifically) in soy can be a cause for concern due to the ability of these compounds to mimic the effects of the hormone oestrogen. One common claim is that high soy intake is detrimental for men particularly, as it is “feminizing”; causing gynecomastia, loss of libido and erectile dysfunction.
So what is the truth? Is soy a health food? A harmful endocrine disruptor? Or simply neutral? In this episode we dive into the research and look at the evidence to date tells us about these questions. We consider two big health outcomes in particular; cardiovascular disease and breast cancer. And then final discuss what this means practically for our dietary choices.

The pathogenesis of obesity is clearly complex. And the need to have a comprehensive model to explain this pathogenesis is important. One such model, termed the Energy Balance Model, has largely been the consensus paradigm of obesity scientists to this point. However, there are others who propose that this is not the correct model of obesity, but rather that obesity pathogenesis can be better explained by a model called the Carbohydrate-Insulin Model (CIM) of obesity.

In this episode the Sigma team discuss the research looking at ‘psychobiotics’; i.e. probiotics that have health impacts on those with pyschiatric disorders or symptoms. They discuss the origins of the research, the gut-brain axis, mechanisms by which gut microbiota could impact mood, and then the human trials to date that have examined probiotics’ effects on mood, anxiety, depression, bipolar disorder and other outcomes.

In this episode Danny and Alan discuss the debate around whether a direct source of the long-chain omega-3 fatty acid DHA should be recommended. Many people do not consume the marine foods (primarily fatty fish) that contain DHA, and higher DHA intakes, DHA status, and omega-3 indices are predictive of certain health outcomes. But the essential omega-3 fatty acid alpha-linolenic acid (ALA) can be consumed from plant sources. So do those who do not consume direct sources of DHA have lower DHA status? Does this matter? And if so, then what pragmatic conclusions can we come to? All of this is covered in this episode.

In this episode Alan and Danny answer a variety of questions sent in from listeners. Topics covered include: fruit consumption, protein dosing, salt for hypotensive people, public health & plant-based diets, and the tactics of quacks.

In this episode we discuss the potential impact of dietary polyphenols on cardiovascular disease risk; including impacts on blood pressure, flow-mediated dilation, and other related outcomes. We talk about some potential mechanisms and then several specific randomized, controlled trials.

In this episode we discuss the potential impact of dietary polyphenols on cognitive health; including cogitnitve funciton, memory, and risk of dementia and Alzeimher’s. We talk about some potential mechanisms, cohort studies, and then direct controlled trials.

James Betts is Professor of Metabolic Physiology at the University of Bath, where he is Co-Director of the Centre for Nutrition, Exercise & Metabolism.
His research employs randomised controlled trials to study the effects of nutrition on metabolic regulation.

In this episode Danny & Alan discuss the impacts of nitrates and nitrites on health. They look at the beneficial impacts of dietary nitrate, as well as issues around nitrites in processed meat.

Vitamin D status is linked to a variety of health outcomes, and avoiding or correcting deficiency is important. However, does supplementing with vitamin D actually benefit most people? Is there evidence for supplementation improving health outcomes like mortality, cancer risk, depression or other outcomes? In this episode Danny and Alan look at intervention trials of vitamin D supplementation.

In this episode Danny and Alan discuss the three primary models used to explain body mass regulation: 1) Set Point Model, 2) Settling Point Model, 3) Dual Intervention Model. They discuss the role of feedback systems, environment, behaviour, as well as discussing both the “thrifty gene hypothesis” and John Speakman’s “drifty gene hypothesis”.

Dr. Gil Carvalho is a medical doctor, researcher and science communicator. With a wide background in several fields, he currently spends a lot of time communicating nutrition science principles to the public.

What is the relationship between shift work and health? What nutrition, sleep and lifestyle strategies can help shift workers? Listen…

Listen on these AppsPodcast TranscriptsGuest InformationProf. Barry Popkin, PhD Prof. Barry Popkin is the W.R. Kenan Jr. Distinguished Professor of Nutrition at the University of North Carolina at Chapel Hill. He is a nutrition and obesity researcher at the Carolina Population Center and is the director of the Interdisciplinary Center for Obesity at UNC. He developed the concept of the Nutrition Transition, the study of the dynamic shifts in dietary intake and physical activity patterns and trends around obesity and other nutrition-related noncommunicable diseases (NCD). Prof. Popkin is involved now in work on program and policy design at the national …

Listen on these AppsPodcast TranscriptsGuest InformationHerman Pontzer,PhD Herman Pontzer, PhD is an Associate Professor of Evolutionary Anthropology at Duke University and Associate Research Professor of Global Health at the Duke Global Health Institute. He is an internationally recognized researcher in human energetics and evolution. Over two decades of research in the field and laboratory, Dr. Pontzer has conducted pathbreaking studies across a range of settings, including fieldwork with Hadza hunter-gatherers in northern Tanzania, fieldwork on chimpanzee ecology in the rainforests of Uganda, and metabolic measurements of great apes in zoos and sanctuaries around the globe. Dr. Pontzer’s work has been …

Listen on these AppsPodcast TranscriptsGuest InformationKevin Hall, PhD Dr. Kevin Hall, PhD is Senior Chief of the Integrative Physiology Section of the Laboratory of Biological Modeling at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). His laboratory investigates how metabolism and the brain adapt in response to a variety of interventions to diet and physical activity. They carry out studies to better understand the complex mechanisms regulating macronutrient metabolism, body composition, and energy expenditure. Recently Dr. Hall was lead author on a study titled ‘Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad …

We discuss the current evidence on sodium intake and cardiovascular disease. Particularly the claim that the sodium-CVD risk relationship exhibits a “J-shaped curve”.

Listen on these AppsPodcast TranscriptsToday’s Topic in Focus:  [03:40] In this episode Danny and Alan discuss the health impacts of alcohol and take a look at the research to answer whether alcohol should be viewed as having a J-shaped curve of risk or zero alcohol being better than any amount. Referenced Material: WHO Statistics – Harmful Use of Alcohol Wood et al., 2018 – Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599,912 current drinkers in 83 prospective studies Egolf et al., 1992 – The Roseto effect: a 50-year comparison of mortality rates “I Have a Question!”  …

Listen on these appsPodcast TranscriptsToday’s Topic in Focus:  [00:51] In this episode Danny and Alan discuss the debate over the impact of dietary cholesterol on LDL-C levels and heart disease risk. Are eggs & cholesterol-rich foods a problem? Let’s dive into the research to find out! Referenced Material: Dietary Guidelines for Americans 2020 – 2025 Hegsted et al., 1993 – Dietary fat and serum lipids: an evaluation of the experimental data Human Atherosclerosis and the Diet – Ancel Keys Keys et al., 1965 – Serum cholesterol response to changes in the diet: II. The effect of cholesterol in the diet …

Listen on these AppsPodcast TranscriptsIn this episode Danny and Alan answer some listener questions, covering a range of topics, including hunger cues, weight-neutral appraoches, body fat distribution, and breakfast and cognition, among others. The guys also discuss the most interesting thing they’ve learned this year and resources on critical thinking. Questions Answered: [08:40] What’s the most interesting thing you’ve learnt this year? [16:30] Is the cliche “hacks to survive the holiday period” a damaging narrative? [18:32] Is the notion that weight loss attempts typically produce more harm than benefit, evidence-based? [21:28] What’s your opinion on intuitive eating? Both the official …

Listen on these AppsPodcast TranscriptsGuest InformationSarah Berry, PhD Dr Sarah Berry is a researcher and senior lecturer in nutritional science at King’s College London. Her research interests relate to the influence of dietary components on markers of cardiovascular disease risk; with a particular focus on the influence of food and fat structure on postprandial metabolism. Dr. Berry has been the academic leader for more than 30 human nutrition studies in cardio-metabolic health. Her research also focuses on the influence of manipulation of food structure and subsequent effects on lipid and carbohydrate bioaccessibility and changes in postprandial metabolism. Ongoing research involves …

Listen on these AppsPodcast TranscriptsGuest InformationNick Hiebert Nick Hiebert writes about nutrition science on his site The Nutrivore, as well as exclusive, comprehnsive posts on his Patreon page. He is the creator of the “Nutrient Density Cheat Sheet”, a nutrition ranking tool for hundreds of whole foods. Nick has a deep interest in a host of nutrition science topics, from nutrient density to saturated fat & cardiovascular disease. He does a lot of deep analysis of raw data and has published some independent meta-analyses on his site.In this episode we discuss: Best and worse ways to calculate the nutrient density …

Listen on these AppsPodcast TranscriptsToday’s Topic in Focus: Calories In, Calories Out [02:15] In this episode Danny and Alan discuss the common misunderstandings and misrepresentations of the energy balance equation, leading to problematic debates over the validity of ‘calories in, calories out’. Sigma Statement: The “Calories In, Calories Out” Confusion: A Comprehensive Guide to Understanding Energy Balance “I Have a Question!” [60:17] Today’s question: “Can you explain what a dose-response relationship is?” Quack Asylum [70:20] Claims by Gary Taubes – Why We Get Fat Random Recommendations [76:20] Alan’s Recommendation: V2 – by Robert Harris  Danny’s Recommendation: The Social Dilemma Joe …

Danny & Alan discuss the impacts of coffee consumption on health; from acute effects and mechanistic actions to epidemiology of disease risk.

Listen on these AppsPodcast TranscriptsGuest InformationJames Hébert, ScD Dr. James Hébert is a nutritional and cancer epidemiologist, currently a distinguished Professor at the University of South Carolina. Dr. Hébert’s professional focus for the past several years has been on developing and refining the Dietary Inflammatory Index™ (DII®), which has now been established as an effective research tool. Dr. Hébert is also a Professor in the Department of Epidemiology and Biostatistics, a Professor of Epidemiology at the Medical University of South Carolina, a Professor of Community Medicine and Epidemiology at the University of South Carolina, School of Medicine, and the Director …

Listen on these AppsPodcast TranscriptsToday’s Topic in Focus: Omega-3 Supplementation & Heart Disease [01:52] 2018 Cochrane Review ASCEND Trial VITAL Trial REDUCE-IT GISSI-Prevenzione Hu et al., 2019 Meta-analysis “I Have a Question!” [66:30] Today’s listener question: “What do you guys think of the new obesity guidelines (UK government plan)?” Details: UK government press release Quack Asylum [87:00] Is a gram of PUFA in chicken worse than 250g of sugar from honey? Random Recommendations [94:20] Alan: Shelock – Netflix Series Danny: Profit & Cocaine – Planet MoneyPrevious EpisodesGo to all Previous EpisodesFan of the Podcast?If you regularly enjoy listening to Sigma …

Listen on these AppsPodcast TranscriptsGuest InformationRebecca Leech, PhD Dr. Rebecca Leech is a Registered Nutritionist and Nutritional Epidemiologist, based at Deakin’s Institute for Physical Activity and Nutrition. Rebecca has a PhD in Nutritional Epidemiology, and in 2018, was awarded an Alfred Deakin Medal for her doctoral thesis, which examined adults’ eating patterns and their associations with diet quality and obesity. Her postdoctoral research, extends on this, and applies novel analytic approaches to understand determinants of food intake at eating occasions and the role of eating patterns in cardiometabolic health in adults. Dr. Leech is funded by an Alfred Deakin Postdoctoral …

Get Sigma Synopsis EmailsIn this episode we discuss:Today’s Topic in Focus: Vegan Diets & Human Health Defining “plant-based” diets Examination of various intervention trials comparing diets Is veganism suitable across the lifestage? Benefits of a vegan diet Are there benefits to excluding animal products? Can the benefits of a vegan diet be gleaned whilst including animal foods? Nutrient considerations if deciding to eat vegan: a well-forumulated vegan diet Should athletes consider: creatine, carnosine, carnitine, leucine, etc.? Links: Research Referenced in this Episode: The BROAD study – Wright et al., 2017 Barnard et al., 2006 Barnard et al., 2009 “An Important …