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Sigma Nutrition Radio

#603: Should Dietary Fiber Be Considered Essential? – Andrew Reynolds, PhD

Sigma Nutrition Radio

Danny Lennon

Health & Fitness, Nutrition

4.8 • 633 Ratings

🗓️ 28 April 2026

⏱️ 59 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

Dietary fiber is widely recognized as an important component of a healthy diet, yet it is not typically classified as an essential nutrient. In this episode, Dr. Andrew Reynolds explores whether that distinction still holds, arguing that the traditional criteria used to define essentiality may be outdated when applied to modern nutrition science.

The discussion moves beyond simply acknowledging the benefits of fiber and instead examines whether it meets the foundational requirements of an essential nutrient. This includes considering its physiological roles, the body's inability to synthesize it in sufficient quantities, and whether low intake leads to a meaningful and reversible dysfunction.

Drawing on evidence from prospective cohort studies, randomized controlled trials, and mechanistic research, Reynolds outlines the strength of the evidence linking higher fiber intakes to reduced risk of cardiovascular disease, type 2 diabetes, colorectal cancer, and premature mortality. 

Reynolds presents a compelling case that fiber may play a fundamental role in maintaining normal physiological function and therefore warrants reconsideration within the framework of essential nutrients.

Timestamps:

  • [03:50] Interview starts
  • [05:53] Understanding essentiality
  • [09:26] Could there be a deficiency-state for fiber?
  • [15:38] What are fiber guidelines based on?
  • [23:52] Fiber and chronic disease risk: dose-response
  • [28:59] Different types of fiber
  • [37:21] Fermentation and SCFAs
  • [42:55] Research priorities ahead
  • [50:04] Low fiber health risks
  • [58:02] Key Ideas segment (Premium-only)

Related Resources:

Transcript

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0:00.0

Hello and welcome to Sigma Nutrition Radio.

0:03.0

This is episode 603 of the podcast.

0:06.6

My name is Danny Lennon.

0:07.8

You are very welcome to the show.

0:09.7

Whether you are a long-time listener or maybe this the first time you're listening in, you are very welcome.

0:14.3

Today, of course, we have another discussion that gets deep into nutrition science.

0:18.1

And I'm going to be welcoming back a previous guest of the podcast

0:21.7

who was on the show back in episode 498, where we discussed some of his excellent and important

0:28.2

work in the area of carbohydrate quality and health. And that is Dr. Andrew Reynolds, who's an

0:35.2

associate professor at the University of Otago in New Zealand.

0:39.5

He has done some excellent and important work that relate to how diet interacts with chronic

0:44.2

disease risks, such as in type 2 diabetes and cardiovascular disease.

0:48.5

He's worked with both randomized control trials as well as with epidemiology, and more and

0:54.0

more his work has been focused in the

0:55.6

area of nutrition epidemiology. And indeed, in our previous discussion, we discussed some of his

1:01.0

very important work that has been used to inform evidence-based dietary and clinical guidelines,

1:06.0

as well as policy from some of the biggest organizations in the world. And part of that was using the conjunction

1:13.9

of both randomized control trials and prospective cohort studies in side-by-side analyses,

1:20.1

something we will maybe discuss today as well. But recently, Dr. Reynolds and his colleagues

1:26.0

authored a comment piece in Nature Food titled

1:29.6

Dietary Fiber as an Essential Nutrient, where they made a case as to why we should maybe

1:36.2

start thinking of dietary fiber as an essential nutrient, despite it not meeting the traditional

...

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