Evidence, Uncertainty, and Nutrition Science | Gordon Guyatt, MD

What do we know about health, nutrition, and medicine — and how confident should we be? In this episode, Dr. Gordon Guyatt, the clinician-scientist who coined the term evidence-based medicine and co-created the GRADE framework, breaks down why so much health and nutrition guidance rests on weak foundations. We dig into the hierarchy of evidence, why observational studies so often mislead us, and what went wrong with hormone replacement therapy and antioxidant vitamins. Dr. Guyatt also explains the intense backlash to the NutriRECS red-meat guidelines and why overstating certainty erodes trust in both science and public health.

We also explore the growing influence of health influencers, why acknowledging uncertainty is essential, and how AI could both help and harm evidence-based decision-making. From the limits of nutrition research to the future of trustworthy guidelines, this conversation offers a clear, honest look at what we know — and what we don’t. If you want rigorous, hype-free insight into how evidence should inform health decisions, this episode is for you.

Timestamps

00:00 Introduction
01:10 What evidence-based medicine actually means
04:28 When low-quality evidence misleads (HRT, antioxidants)
07:29 Why most nutrition research is low certainty
11:29 The NutriRECS red-meat guidelines and backlash
17:55 How the nutrition field overstates certainty
21:02 Influencers and misinformation
23:42 AI’s role in evidence-based decision-making
31:58 Why uncertainty and humility matter
32:34 Advice for clinicians and researchers
37:14 How to make recommendations with low-quality evidence

Dr. Gordon Guyatt

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McMaster University: https://experts.mcmaster.ca/people/guyatt

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