The Dr. Gabrielle Lyon Show
The Truth About Nutrition: How You Can Take a Science-Based Approach | Bradley Johnston PhD
Tue, 25 Feb 2025
Misinformation in nutrition is rampant. From demonizing red meat to hyping plant-based diets, conflicting advice has left many people confused about what’s truly evidence-based. In this episode, I am joined by Dr. Bradley Johnston, an expert in evidence-based nutrition and public health policies, to separate fact from fiction. With nearly 200 peer-reviewed publications, Dr. Johnston has challenged conventional wisdom—including recommendations from major organizations like the World Health Organization. He shares how evidence-based practices should guide our dietary choices, the importance of systematic reviews and meta-analyses, and how cognitive biases influence the research we trust.Key Points: How evidence-based guidelines are formed—and why they sometimes changeThe three pillars of evidence-based practice and why patient values matterWhy most nutrition studies aren’t as strong as we think—and how to critically evaluate themWhat the best available research actually says about dietary patterns for longevityThe role of AI in research and whether it’s a help or hindrance to scientific rigorIf you’ve ever questioned dietary guidelines, nutrition headlines, or conflicting health advice, this episode is a must-listen. Get ready to rethink everything you thought you knew about nutrition.Who is Dr. Bradley Johnston? Dr. Bradley Johnston is an Associate Professor at Texas A&M University, specializing in evidence-based nutrition, and the methodology of patient-reported outcomes, randomized clinical trials, systematic reviews, and clinical and public health practice guidelines. With a PhD in experimental medicine from the University of Alberta and post-doctoral training in evidence-based practice, epidemiology and biostatistics from Oxford and McMaster University, his research focuses on advancing human health research methodology to improve clinical and dietary practice recommendations and public health policies. He co-leads EvidenceBasedNutrition.org and NutriRECS, develops nutrition education resources (e.g. Nutrition Users’ Guides), and currently serves as Co-Chair of the Canadian Pediatric Obesity Management Guidelines, ensuring clinical and public health guidelines are backed and transparently supported by the best available evidence, including end user values and preferences, absolute estimates of effect and the certainty of evidence for estimates of effect. His overall aim is to empower patients, clients and members of the public to make fully-informed health care decisions based on the central tenets of evidence-based practice and policy. This episode is brought to you by: Timeline -Code DRLYON for 10% OFF https://timelinenutrition.com/DRLYONPuori - Code DRLYON for 20% OFF - https://puori.com/DRLYONBonCharge - Code DRLYON for 15% OFF - https://boncharge.com/DRLYONARMRA - Code DRLYON for 15% off! - https://armra.com/DRLYON/Find Dr. Bradley Johnston at: Evidence Based Nutrition - https://www.evidencebasednutrition.orgNutrition Users' Guides -https://www.evidencebasednutrition.org/nutrition-user-guidesTexas A&M University -
Chapter 1: Why is there so much misinformation in nutrition science?
The loaded term and phenomenon of misinformation has left many Americans asking, what if everything I know about nutrition is wrong? How often have we trusted headlines only to find years later the advice was misleading or incomplete? From demonizing red meat to hyping plant-based diets, nutrition science has become a battleground for conflicting advice and misconceptions.
Hi, I'm Dr. Gabrielle Lyon, and today we're cutting through the noise to uncover the truth about what we really know about nutrition. Joining me is Dr. Bradley Johnston, a world-renowned expert and researcher who's reshaping the way we think about food and health.
With almost 200 peer-reviewed papers, Dr. Johnston has been at the forefront of nutrition science who has tackled some of the most intense topics. His groundbreaking studies have sparked global debates and even challenged the advice from organizations like the World Health Organization. In this episode, we'll tackle how much influence we have over the dietary advice we're told to trust.
We're also going behind the scenes to explore how public health policies are shaped, uncover hidden biases in nutrition science, and give you actionable tips for making smarter food choices, backed by evidence, not hype. So my friends, if you've ever felt overwhelmed by conflicting advice about what to eat, or you've questioned whether you're getting the full story, this episode is for you.
Join me as we separate fact from fiction when it comes to nutrition. Dr. Bradley Johnston, welcome to the show. I am so thrilled to have you here. I've been a huge fan of your work. I think that you've done a tremendous job at helping us think about evidence-based practices, how we can sift through information. And you have your PhD. I believe that you're also a professor now. Are you teaching?
Yes.
Yes, I'm a professor, Texas A&M University.
Amazing. Amazing. Tell us a little bit about your background, what your PhD is in, how you became interested in the work that you're doing now.
Yeah, sure. So thanks for asking. Thanks for having me. My undergraduate degree is in kinesiology, and then I did doctoral training in experimental medicine at the University of Alberta. And then from there, I did postdoctoral training in evidence-based health care at Oxford University or University of Oxford and McMaster University in clinical epidemiology and biostatistics.
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Chapter 2: Who is Dr. Bradley Johnston and what is his background?
Oh, seven trials on the Mediterranean-style diet for the outcome of whole-cause mortality.
Okay.
And in fact, I think there's now eight.
Amazing. In my mind, I'm thinking, okay, well, that's only seven, but perhaps two would be enough. When can we say there's enough data to have an evidence-based practice?
Interesting. Well... It's actually more important than the number of studies is the size of the studies, how many participants were enrolled and followed and completed. If it's an experimental study, it's different. We have lots of very large cohort studies. It doesn't necessarily mean that we have a lot of certainty in those estimates of effect.
But I would, you know, you look at the number of studies, you look at the sample size, and then ideally there's at least a few studies that have replicated the finding in different geographic regions.
Yeah.
Is there, do you think that there is, and this is just a personal question in the way that, do you think that there's risk if we are not doing evidence-based practices? Meaning, you know, I don't know. Do you, because you spent your life studying this, really bringing this process forward, right?
Well, there's a risk in that we can have walkbacks if we got it wrong in terms of the recommendations that we've made. And that's a risk, and you risk the trust of the public, for example, or the trust of your patient or your patient base if it turns out that you're making recommendations either at a clinical level or a public health level.
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Chapter 3: What is evidence-based practice and how does it apply to nutrition?
Yeah, I think another important component is I think some people that maybe have a perception that if you only have observational studies for a public health question or a clinical question, then automatically it's going to be a weak or conditional recommendation. Automatically, the certainty of evidence is low. That's not necessarily always the case using the GRADE method.
So some people might be familiar with the old school static hierarchy of evidence where at the top were systematic reviews and meta-analysis of RCTs. And after that was systematic reviews of observational studies. And below that was RCT, a single RCT, single cohorts. Grade is a sophisticated approach.
It kind of starts to some degree with that hierarchy, but the evidence can move up or down depending on a whole bunch of questions we ask of the body of evidence. There are examples of observational data only that move up from low to possibly even high certainty evidence. So the example that most people would be familiar with is smoking and lung cancer, right?
We don't have randomized trials of smoking and the risk of lung cancer, but we have a lot of observational data that And we have observational data that shows large exposure effects and a very clear and reproducible dose response curve. So with that observational data, which has its limitations, we do have high certainty that smoking is a problem when it comes to risk of lung cancer.
You created a website. It's evidencebasednutrition.org. Can you tell me a little bit about it and why you created it? It's actually phenomenal. We'll put a link to it. But why did you create this and how can someone utilize this?
Yeah, sure. So we created it, a group of us who kind of work together regularly, a lot of people that have kind of come through McMaster University.
The home of evidence-based practices. Yeah.
Well, I mean, a lot of people, I guess, have websites now. It's a resource where we kind of park materials to help people interpret the literature, like our nutrition users guides that we're starting to publish.
Yeah, I saw that.
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