Understanding the complexities of diet-disease relationships requires a nuanced approach to nutritional science. Unlike other scientific disciplines, nutrition research often grapples with the inherent challenges of studying dietary patterns and nutrient intakes in free-living populations over long periods.

The cumulative effects of dietary exposures, combined with the necessity to control for confounding factors such as total energy intake and population-specific dietary habits, highlight the need for rigorous study designs and careful interpretation of findings.

Despite their utility, these methods are often misunderstood or misrepresented in public discourse. Addressing these misunderstandings requires a clear communication of key principles underpinning nutritional science, including the role of cumulative exposure, the importance of contextualizing absolute and relative risks, and the necessity of evaluating the long-term effects of dietary patterns.

This episode aims to provide a comprehensive overview of these essential ideas, equipping readers with the tools to critically appraise the evidence and engage meaningfully with the ongoing conversation around nutrition research.

• [03:26] Understanding nutrition science: core concepts
• [06:01] Standards of proof in nutrition research
• [19:39] Unique challenges in nutrition research
• [26:30] High vs. low exposure in nutrition studies
• [34:34] Challenges in nutrition randomized control trials
• [39:29] Understanding null by design in nutrition trials
• [41:58] The importance of temporal relationships in diet and disease
• [43:55] Relative risk vs. absolute risk
• [57:16] The role of substitution and adjustment in nutrition studies

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• Episodes referenced:
  • 531: Correlation, Causation & Cliché
  • 478: Exposures in Nutrition – Why They’re Crucial to Understand
  • 511: Null By Design – When “No Effect” Doesn’t Mean No Effect
  • 378: Nutritional Epidemiology
  • 472: Compared To What? – Understanding Food Substitution Analysis & Adjustment Models

This episode focuses on the intersection of nutrition, lifestyle, and women’s health, with a particular emphasis on managing complex conditions such as PCOS, endometriosis, and premenstrual dysphoric disorder (PMDD).

Registered dietitian Marjorie Nolan Cohn shares insights from over two decades of clinical practice, highlighting the importance of addressing foundational health behaviors—such as adequate sleep, hydration, and nutrient-dense dietary patterns—before introducing targeted interventions like supplementation.

Marjorie explores the nuanced relationship between body weight, metabolic health, and fertility, while addressing misconceptions around weight loss as a primary health goal. The episode examines the role of long-term, individualized care in improving symptoms and outcomes for women experiencing significant menstrual-related challenges.

Practical considerations for practitioners, including strategies to build trust, identify key barriers, and provide holistic support, are outlined alongside the importance of interdisciplinary collaboration to improve care quality.

Marjorie Nolan Cohn is a registered dietitian with a Masters Degree in Food and Nutrition Science from the Indiana University of Pennsylvania. She is the Clinical Director of Berry Street, a company providing virtual in-network nutritional counseling to people across the US.

• [04:32] Beginning of the interview
• [08:39] The role of nutrition in fertility
• [13:40] Understanding PCOS and endometriosis
• [16:28] Barriers to accurate women’s health diagnoses
• [19:03] Exploring diet and lifestyle strategies
• [23:28] Addressing challenges in women’s health and nutrition
• [39:01] Closing remarks and final takeaways

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• Enroll in the next cohort of our Applied Nutrition Literacy course
• Guest website: Berry Street

Over the past couple of decades, renowned researcher Dr. Marie-Pierre St-Onge has uncovered fascinating links between how we sleep and what we eat, revealing how these two lifestyle factors influence energy balance, cardiovascular health, and metabolic function.

In this episode we’ll explore Dr. St-Onge’s findings on sleep regularity and its association with reduced mortality risk, providing actionable insights for optimizing your lifestyle. With a focus on combining rigorous methodologies and controlled dietary interventions, her research sheds light on the complex mechanisms connecting sleep, diet, and metabolic health.

Timestamps:

• [03:39] Dr. St-onge's academic journey and evolution of her research interests
• [07:03] Overcoming methodological challenges in sleep and nutrition research
• [10:20] The importance of sleep regularity for health
• [15:44] Exploring the bidirectional connection between diet and sleep
• [23:40] Unpacking the mechanisms linking diet to sleep quality
• [37:33] Practical recommendations for optimizing sleep and diet

Links:

• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course
• Article: How Sleep & Nutrition Interact – Alan Flanagan, PhD
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