#555: What Should the Dietary Guidelines Say? – Prof. Christopher Gardner
Release Date: 03/04/2025
#571: Is Zone 2 Training Actually Best for Health? – Prof. Brendon Gurd
Sigma Nutrition Radio
In recent years “Zone 2 training” has gained immense popularity in fitness and health circles, often being proclaimed the “best” cardiovascular training for metabolic health. Zone 2 training is sustained, low-intensity exercise below the lactate threshold that is commonly employed by many elite level endurance athletes, with a variety of proposed performance benefits. This led to interest from health-conscious folks about its ability to improve markers like VO2 max and mitochondrial function, which are associated with better health outcomes and longevity. Prof....
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#570: Fructose: Metabolism, Claims & Context for Risk – Scott Harding, PhD
Sigma Nutrition Radio
Fructose has often been labeled a uniquely damaging nutrient, blamed for obesity, diabetes, and other metabolic diseases. But does fructose truly have unique harmful effects or are the risks associated with it related to context and quantity? The episode explores how fructose is metabolized in the body, why it gained a reputation for being problematic, and what the scientific evidence says about fructose in our diets. You will gain insight into why fructose was singled out in the past (e.g., its unique pathway in the liver and lack of insulin response), and how newer studies put those concerns...
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SNP42: Is Vitamin A Good or Bad for Bone Health?
Sigma Nutrition Radio
Vitamin 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...
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#569: The History of Fat, Cholesterol & Heart Disease
Sigma Nutrition Radio
The idea that saturated fat might be harmful to our health has sparked controversy for decades. In recent years, counter-narratives have surged: suggesting that concerns over saturated fat were overblown, that LDL cholesterol doesn’t matter, or that the original diet-heart hypothesis has been debunked. These claims have become especially popular in online wellness spaces and certain dietary communities, often wrapped in compelling but misleading rhetoric. So what does the best available evidence actually say? And how should we think about saturated fat, LDL cholesterol, and cardiovascular...
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#568: Does the Maternal Diet Impact Risk of ADHD & Autism? – David Horner, PhD
Sigma Nutrition Radio
To what extent can maternal nutrition during pregnancy influence a child’s later cognitive or behavioural development? While genetic and environmental factors are known to contribute to neurodevelopmental outcomes such as ADHD and autism, growing attention is being paid to the potential role of prenatal exposures, including dietary patterns. Yet, evidence in this area remains limited, and causality is difficult to establish. One recent study aimed to explore this question by analysing how maternal diet quality during pregnancy (specifically, adherence to a Western-style dietary pattern)...
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#567: Did Big Sugar Hijack the Food Pyramid? Were Low-fat Diets a Scam that Damaged Our Health?
Sigma Nutrition Radio
For decades, dietary guidelines—and the Food Pyramid in particular—have been at the center of heated debates and considerable controversy. These guidelines have often been accused of being influenced by industry interests, oversimplifying nutritional nuance, or even directly contributing to rising obesity and metabolic disease rates. In this episode, we critically assess common claims surrounding the Food Pyramid, including whether it was truly shaped by vested industry interests, if it encouraged harmful dietary shifts toward excessive carbohydrate and sugar consumption, and whether the...
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SNP41: Do Certain Foods Really Cause Inflammation – And Are Anti-Inflammatory Diets the Answer?
Sigma Nutrition Radio
Inflammation has become a nutrition buzzword, often used in extreme or misleading ways. This episode aims to clarify what inflammation is, how it relates to diet and health, and whether specific foods truly provoke inflammatory responses in the body. The episode provides a nuanced, evidence-based look at inflammation and diet. It explains the difference between acute and chronic inflammation, outlines the role of chronic low-grade inflammation in disease, and emphasizes that overall dietary patterns – rather than any single food – are what influence our inflammatory status. Commonly...
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#566: Can We Maintain Weight Loss? Pharmacology and Behavior – Tara Schmidt, RD
Sigma Nutrition Radio
GLP-1 receptor agonists have changed the landscape of obesity treatment, offering levels of weight loss once thought unattainable without surgery. But what happens after the weight is lost? And can we really talk about success without talking about maintenance? While much of the public discourse fixates on dramatic weight loss numbers, the harder question is what comes next. Can lifestyle interventions alone sustain weight loss after GLP-1 cessation? How do metabolic adaptations and behavioral relapse factor in? And what does the data actually show about relapse rates, nutritional adequacy,...
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#565: How Zinc Insufficiency Impacts Inflammation, Immunity & Aging – Prof. Emily Ho
Sigma Nutrition Radio
Zinc is an essential micronutrient that often flies under the radar, despite being vital for hundreds of enzymes and transcription factors involved in immunity, antioxidant defense, and DNA repair. A surprisingly large segment of the population may not get enough – an estimated 10% of U.S. individuals consume less than half the recommended zinc intake, putting them at risk of deficiency. In this episode, Prof. Emily Ho discusses how even mild zinc insufficiency can impair immune function, promote chronic inflammation, and accelerate aspects of aging. She delves into the concept of...
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#564: Is Protein’s Appetite-Suppressing Power Overstated?
Sigma Nutrition Radio
In this episode, we take a deep dive into the commonly held belief that protein is the most satiating macronutrient. It’s an idea that shows up frequently in both clinical guidance and popular nutrition discourse: if you want to feel fuller, eat more protein. But how robust is that claim when you drill into the details of the evidence? To explore this, Alan and Danny examine the complex interplay between protein intake, satiety, and energy intake. We look at both historical and recent literature, including work from Kevin Hall’s group, that raises important questions about how much of...
info_outlineEvery five years, the U.S. Dietary Guidelines are updated based on the latest scientific evidence to help shape national nutrition recommendations. A panel of experts was assembled to review the existing research, evaluate new findings, and provide recommendations that will inform the next edition of the guidelines.
One of the committee members involved in this process is Professor Christopher Gardner, a leading nutrition scientist at Stanford University, who joins us to share key insights from the committee’s work.
In this discussion, Professor Gardner provides an inside look into how the committee evaluated dietary patterns, the role of plant-based proteins, and the ongoing debate surrounding ultra-processed foods. He explains the rigorous process of reviewing scientific literature, the challenges in translating research into policy, and the critical role of health equity in shaping the recommendations.
By exploring these themes, this episode aims to provide clarity on the scientific foundation behind the upcoming dietary guidelines. Whether you’re a nutrition professional, researcher, or someone interested in how dietary recommendations are formed, this conversation sheds light on the key discussions shaping the future of nutrition policy.
Timestamps
- [03:38] Interview begins
- [07:18] The rigorous process behind formulating dietary guidelines
- [12:10] Key questions addressed and major findings from the report
- [25:41] Identifying nutrients of concern and refining dietary patterns
- [33:39] The importance of health equity in dietary recommendations
- [36:04] Reassessing dairy’s role in different population groups
- [41:05] Shifting the focus towards plant-based protein sources
- [47:52] The debate on ultra-processed foods and public health implications
- [58:24] Key Ideas segment (Premium-only)
Related Resources
- Enroll in the next cohort of our Applied Nutrition Literacy course
- Subscribe to Sigma Nutrition Premium
- Join the Sigma email newsletter for free
- Scientific Report of the 2025 Dietary Guidelines Advisory Committee
- Previous episode with Prof. Gardner: Episode 223