6d ago

Dr. David Klurfeld on Dietary Guidelines - Why the WHO IARC position is biased

Dr. David Klurfeld—longtime USDA scientist and one of the few insiders to publicly challenge the WHO's classification of red meat as a carcinogen. We go deep into the flawed evidence behind the infamous 2015 IARC report, why nutritional epidemiology often fails to prove causality, and how a small group of researchers helped shape global policy with low-quality science. If you've ever felt confused about meat, saturated fat, or dietary guidelines, this conversation will help you think critically about what “counts” as evidence—and who gets to decide.

We cover:

Dr. Klurfeld’s personal journey and lessons from a career in public health
Why the 2015 IARC red meat classification was based on weak and inconsistent evidence
How observational studies and “allegiance bias” mislead nutrition science
The politics of dietary guidelines and the role of the USDA and WHO
What the media got wrong—and why red meat remains a nutrient-dense food

Whether you're a clinician, dietitian, or simply trying to make better nutrition decisions, this episode is a powerful reminder that bias, groupthink and weak data can distort science and mislead the public. We need to be discerning about the nutrition and health advice we follow.

Who is Dr. David Klurfeld?

Dr. David Klurfeld is a nutritional scientist and former National Program Leader for Human Nutrition at the USDA’s Agricultural Research Service. He also served as Professor and Chair of Nutrition and Food Science at Wayne State University and Associate Editor of The American Journal of Clinical Nutrition. He has authored more than 200 scientific publications and was one of 22 experts invited to the 2015 IARC working group on red meat and cancer. He is a longtime advocate for scientific integrity in public health policy.

Timestamps

00:00 – Dr. Gabrielle Lyon introduces Dr. David Klurfeld and the controversy around red meat and cancer.
03:18 – Dr. Klurfeld explains his unconventional path into nutrition science and his early influences.
06:07 – He describes how "allegiance bias" distorts nutrition research outcomes.
09:08 – Klurfeld calls the IARC red meat classification “the most frustrating professional experience of my life.”
12:15 – He explains why epidemiology and food questionnaires are unreliable for determining dietary risk.
15:30 – Red meat is misleadingly grouped with engine exhaust and radiation in cancer risk categories.
22:15 – Many IARC scientists had pre-existing biases and used the panel to reinforce prior publications.
26:08 – Klurfeld critiques the misuse of correlation in nutrition
32:06 – He debunks the commonly cited 17% increase in colorectal cancer risk from red meat.
48:44 – Activist groups filed FOIA requests to access years of Klurfeld’s emails during public-private research.
1:09:21 – He explains why nitrogen content alone is an inadequate way to assess protein quality.

Dr Klurfeld was ON the WHO IARC panel that classified Red Meat as a type 2 carcniogen. His experience is inside baseball of how that committee made its decision, specifically little gem: https://www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf

IARC Monographs evaluate consumption of red meat and processed meat

Lyon, France, 26 October 2015 – The International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, has evaluated the carcinogenicity of the consumption of red meat and processed meat.

Red meat

After thoroughly reviewing the accumulated scientific literature, a Working Group of 22 experts from 10 countries convened by the IARC Monographs Programme classified the consumption of red meat as probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect. This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer.

Key points he brings up about the WHO 2015 IARC process:

Not a systematic review
Not a meta-analysis of epidemiology
Decisions made from individual observational studies
Mechanistic studies (say whats possible, don't demonstrate in humans)
800 Studies were in the literature pool, but only used 18 that supported the conclusions. 782 were thrown out....
Majority voting for conclusions
About 2/3 of the committee members were vegetarian, but didn't feel necessary to disclose this as a bias.
IARC members are self nominated

So a group of volunteers decides by majority vote without scientific rigor what is and isn't causal

Klurfeld has a excellent critique of epidemiology as low quality evidence at 12:00

He has since retired in 2021? - So he can speak about his experiences now without impacting his career.

Dr. Klurfeld is very well spoken, very much worth your time to listen to him.

Here is his publication history as seen by google scholar: https://scholar.google.com/citations?user=Ym5Og20AAAAJ&hl=en

2 comments

Dr Klurfeld was ON the WHO IARC panel that classified Red Meat as a type 2 carcniogen. His experience is inside baseball of how that committee made its decision, specifically little gem: https://www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf
IARC Monographs evaluate consumption of red meat and processed meat
Lyon, France, 26 October 2015 – The International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, has evaluated the carcinogenicity of the consumption of red meat and processed meat.
Red meat
After thoroughly reviewing the accumulated scientific literature, a Working Group of 22 experts from 10 countries convened by the IARC Monographs Programme classified the consumption of red meat as probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect. This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer.
Key points he brings up about the WHO 2015 IARC process:
Not a systematic review
Not a meta-analysis of epidemiology
Decisions made from individual observational studies
Mechanistic studies (say whats possible, don't demonstrate in humans)
800 Studies were in the literature pool, but only used 18 that supported the conclusions. 782 were thrown out....
Majority voting for conclusions
About 2/3 of the committee members were vegetarian, but didn't feel necessary to disclose this as a bias.
IARC members are self nominated
So a group of volunteers decides by majority vote without scientific rigor what is and isn't causal
Klurfeld has a excellent critique of epidemiology as low quality evidence at 12:00
He has since retired in 2021? - So he can speak about his experiences now without impacting his career.
Dr. Klurfeld is very well spoken, very much worth your time to listen to him.
Here is his publication history as seen by google scholar: https://scholar.google.com/citations?user=Ym5Og20AAAAJ&hl=en
- At 1h he makes a really good point; If nutritional epidemiology "science" is so weak that it needs lower standards of evidence then actual science it shouldn't be called science. It shouldn't be presented with the same rigor and confidence as empirically demonstrated science.