#584: EAT-Lancet: Does the Planetary Health Diet Improve Human Health?
Sigma Nutrition Radio
How should we think about diets that claim to optimise both human and planetary health? Can a single “reference diet” really balance the complex trade-offs between nutrition adequacy, chronic disease prevention, and environmental sustainability? These questions have gained renewed attention with the release of the 2025 update to the EAT-Lancet Planetary Health Diet. The original 2019 report proposed a mostly plant-based dietary pattern designed to improve population health while staying within planetary boundaries. But since then, new data have emerged—on nutrient requirements, disease...
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#583: Ultra-Processed Foods & Fixing the Food Environment – Kevin Hall, PhD
Sigma Nutrition Radio
Ultra-processed foods have become central to the way we eat and to many of the challenges we face in public health nutrition. They dominate supermarket shelves, shape population diets, and often appear as the prime suspect in rising obesity and metabolic disease rates. But beyond the label itself, what exactly makes these foods problematic? Is it their nutrient composition, their texture and palatability, the rate at which we consume them, or the broader environments that make them so accessible and appealing? The debate around ultra-processed foods sits at the intersection of metabolic...
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SNP45: Antioxidants – What You Need To Know
Sigma Nutrition Radio
This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to . What exactly are “antioxidants,” and why do they get so much hype? We often hear that blueberries, dark chocolate, and red wine are healthy because they’re packed with antioxidants – but is the story really as simple as “more antioxidants = better health”? In this episode, Danny explores the true role of antioxidants in the body, challenging simplistic narratives. Are antioxidants magic molecules that single-handedly prevent aging and disease? Or is the...
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#582: GLP-1 Agonists: Side Effects, Management and Diet – Dr. Spencer Nadolsky
Sigma Nutrition Radio
GLP-1 receptor agonists have emerged as a groundbreaking tool in obesity treatment. In this episode, Dr. Spencer Nadolsky (an obesity specialist) explains how these medications are now yielding unprecedented weight loss outcomes in people with obesity. The discussion centers on GLP-1 agonist drugs like semaglutide and tirzepatide: how they work, how much weight loss they can produce, and why they represent a paradigm shift in obesity management. Importantly, the conversation addresses practical aspects of using these drugs, including managing their side effects and optimizing...
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#581: What Is Successful Public Nutrition Policy? And Why Is It So Hard to Achieve? – Emily Callahan, RD, MPH
Sigma Nutrition Radio
Public nutrition policy plays a critical role in shaping population health through laws, guidelines, and programs that influence what people eat. In this episode, Emily Callahan, an expert in nutrition policy, talks about why public nutrition policies often fall short and what “success” looks like. They discuss how evidence-based nutrition interventions can stall due to political or practical barriers, and explore examples ranging from federal food assistance programs to sodium reduction initiatives. Crucially, they address how to evaluate if a policy has worked and highlight emerging...
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#580: Sodium Bicarbonate for Sports Performance – Prof. Lewis Gough
Sigma Nutrition Radio
Sodium bicarbonate is one of the most consistently supported ergogenic aids in sports nutrition research, yet its underlying mechanisms and real-world applications remain widely misunderstood. More recent developments have focused on how to optimise both the timing and formulation of supplementation. The “individualised ingestion timing” approach has emerged as a practical strategy, recognising that the time-to-peak blood bicarbonate concentration varies considerably between individuals. Similarly, novel formulations are being explored to address issues with gastrointestinal distress and...
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#579: Is Your Chronotype Hard-Wired or Modifiable? And What Does It Mean for Health?
Sigma Nutrition Radio
In this episode, we explore the concept of chronotype, which reflects an individual’s biological circadian timing and how it manifests in preferred sleep–wake patterns. Understanding chronotype is important because it differs from simple diurnal preference, which may be shaped by lifestyle or psychological factors rather than biology. We examine how chronotype is measured, from gold-standard laboratory methods to validated questionnaires used in field studies. The discussion also highlights the importance of accounting for sleep debt when estimating true biological timing. Finally, we...
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#578: Creatine For Brain Health: Overhyped Trend or Science-based Intervention? – Prof. Eric Rawson
Sigma Nutrition Radio
Creatine is best known as a sports supplement for enhancing muscle strength and high-intensity performance. But could it also improve brain health and cognitive function? Or are such claims overhyped? If creatine can support brain health, it could have implications for aging, neurodegenerative diseases, concussion recovery, and mental fatigue. In this podcast episode, Professor Eric Rawson discusses what current science says about creatine’s effects on the brain, including memory, executive function, and protection against neurological stress. Professor Rawson provides context on how...
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Is There a Limit to Energy Expenditure? And What Happens When We Push It? (SNP44)
Sigma Nutrition Radio
Energy expenditure is one of the most fundamental yet often misunderstood aspects of human physiology. A central question is whether there is a ceiling to how many calories we can burn, and what happens when activity levels approach that limit. Grasping these dynamics is essential for health professionals and researchers, as energy balance directly influences body weight regulation, metabolic health, and athletic performance. Emerging research shows that our bodies regulate calorie burn not in a fixed manner, but through adaptation and compensation, revealing that the “calories in vs....
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#577: Ultra-processed vs. Minimally Processed Diets: UPDATE Trial – Samuel Dicken, PhD
Sigma Nutrition Radio
Recently a new trial was published in Nature Medicine comparing the effect of ultra-processed versus minimally processed diets. Specifically, the UPDATE trial compared these two diets in the context of a healthy dietary pattern (in line with the UK’s EatWell Guide). This eight-week randomized, crossover trial generated a lot of discussion and was largely seen as being a really useful addition to the evidence base, and providing answers to some previously unexamined questions. In this episode the study’s lead author, Dr. Samuel Dicken, explains the background context for the UPDATE trial,...
info_outlineVitamin A is often one of the less-discussed micronutrients in relation to bone health, taking a back seat to nutrients like calcium and vitamin D. Yet this fat-soluble vitamin plays a fundamental role in skeletal development, remodeling, and mineral homeostasis. It influences gene expression in both osteoblasts and osteoclasts, and contributes to the regulation of bone turnover throughout the lifespan.
But what makes vitamin A particularly interesting, and controversial, is that its effects on bone appear to follow a double-edged pattern. While it’s essential for bone formation, several large epidemiological studies have suggested that chronically high intakes of preformed vitamin A may actually increase the risk of osteoporosis and fracture, especially when consumed as retinol from supplements or high-liver diets. And yet, the picture is not so clear-cut.
This raises compelling questions:
- Is the concern over vitamin A and bone health justified, or is it a case of context-dependent risk?
- Can vitamin A, when combined with adequate levels of D and K, actually support bone strength?
- And are there thresholds above or below which risk increases?
In this episode, we explore the human evidence on vitamin A and skeletal health, looking not only at fracture outcomes and bone mineral density data, but also at nutrient interactions, mechanistic plausibility, and the implications for supplement use in well-nourished populations.
Note: This is a Premium-exclusive episode, so you will only hear a preview on this public feed.
Timestamps
- [00:23] Vitamin A and bone health: an overview
- [02:50] Forms of vitamin A: retinol and carotenoids
- [04:16] Mechanisms of vitamin A in bone physiology
- [17:52] Nutrient interactions: vitamin A, D, and K
- [31:03] Practical takeaways and recommendations
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