Listen Here:
For a full list of apps, go here. Or simply search “Sigma Nutrition” in your app of choice. Or listen directly on the Sigma website here.
Introduction
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 risk in the current day?
In this wide-ranging interview, originally recorded for the Chasing Clarity podcast, Alan and Danny explore the scientific consensus around saturated fat’s impact on blood lipids, why LDL and apoB are central to atherosclerotic disease, and how dietary patterns can meaningfully reduce risk.
Importantly, they also address some of the most persistent myths and half-truths that fuel confusion, from flawed interpretations of the Seven Countries Study to misrepresentations of newer meta-analyses.
- [03:41]How do we know saturated fat impacts LDL-C?
- [05:28]Metabolic ward studies and key findings
- [11:13]The Keys equation and subsequent research
- [17:17]Epidemiology and long-term studies
- [31:48]The Seven Countries Study
- [44:25]Understanding the impact of saturated fat on blood lipids
- [47:23]Historical and research perspectives on saturated fat
- [50:43]Practical dietary strategies for improving blood lipids
- [53:48]The Portfolio Diet and other dietary interventions
- [58:07]The role of pharmacology in managing blood lipids
- [01:00:58]Addressing misconceptions and common claims
- [01:13:57]Key ideas segment (premium-only)
The Hosts
Click through to your app of choice to listen and subscribe:
Dr. Alan Flanagan has a PhD in nutrition from the University of Surrey, where his doctoral research focused on circadian rhythms, feeding, and chrononutrition.
This work was based on human intervention trials. He also has a Masters in Nutritional Medicine from the same institution.
Dr. Flanagan is a regular co-host of Sigma Nutrition Radio. He also produces written content for Sigma Nutrition, as part of his role as Research Communication Officer.
Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.
Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.
Related Resources
Latest evidence-based insights from our nutrition science team
Introduction to this Episode
Few topics in nutrition generate as much confusion, or as much passionate debate, as the link between saturated fat, blood cholesterol, and heart disease. While public narratives have shied dramatically in recent years, with some voices claiming saturated fat was unfairly demonized or that LDL cholesterol “doesn’t matter,” the actual scientific evidence tells a far more consistent story.
This episode offers a comprehensive exploration of how dietary fat became central to our understanding of cardiovascular risk. Tracing the arc from early post-WWII observations to tightly controlled metabolic ward studies in the 1950s, it walks through landmark research by Ancel Keys and others, into the robust modern evidence from randomized trials, population studies, and mechanistic data. The episode explains how scientists uncovered the powerful influence of saturated fat on blood cholesterol levels and how that, in turn, impacts atherosclerosis and cardiovascular disease.
Importantly, it also highlights how scientific focus sharpened over time, moving from total cholesterol to LDL cholesterol and eventually apoB-containing lipoproteins, as our understanding of the atherosclerotic process deepened. What emerges is a remarkably consistent finding: diets high in saturated fat raise cholesterol and drive heart disease, while replacing saturated fat with unsaturated fat lowers cholesterol and reduces risk. This forms the backbone of the diet-heart hypothesis and continues to shape current dietary guidelines.
In an era of conflicting dietary narratives, revisiting this robust and evolving body of evidence is essential. Cardiovascular disease remains the leading cause of death globally, and LDL cholesterol is a major modifiable risk factor. Understanding the science behind dietary fat’s role in heart disease helps clarify why guidelines exist and why claims that saturated fat is harmless don’t hold up to scrutiny.
This episode also tackles persistent myths: that the dangers of saturated fat were invented by the sugar industry, or that modern nutrition guidelines are based on flawed or outdated science. With clear explanations, historical context, and reference to rigorous data, the conversation helps health professionals and informed listeners cut through the noise and evaluate dietary advice with clarity and confidence.
