In today’s episode Dr Matthew Nagra returns to The Proof to break down a new JAMA Internal Medicine study on butter, plant-based oils, and mortality.

Over 200,000 Americans were followed for 33 years — so what did the research really find?

We unpack the study’s most talked-about claims, including whether swapping just 10g of butter for plant-based oil could lower your risk of early death.

Plus, we dive into the bigger picture: Why fats are so polarising, the debate around seed oils, and how to navigate nutrition science in an era of misinformation.

Specifically, we cover:

Inside a Controversial New Study on Butter and Plant Oils (00:00)
How the 33-Year Nutrition Study Was Conducted (00:47)
What Observational Studies Can (and Can’t) Tell Us (03:01)
The Truth About Food Frequency Questionnaires (08:03)
Surprising Patterns in Butter and Oil Consumption (17:52)
Why One Common Oil Performed Better Than Expected (22:50)
Are We Misunderstanding Nutrition Guidelines? (26:13)
What Happens When Oils Are Heated Over and Over (28:28)
Do Oils Measure Up to Whole Food Fat Sources? (31:04)
The Great Oil Debate: A Preview and Reflection (34:07)
A Smarter Way to Navigate Conflicting Health Advice (43:40)

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Simon Hill, MSc, BSc (Hons)

• Creator of theproof.com

• Host of The Proof with Simon Hill

• Author of The Proof is in the Plants

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