#483: What are the Effects of Very High Fiber Intakes?

In Podcasts by Danny Lennon4 Comments


The benefits of consuming a higher fiber diet have been consistently demonstrated in nutrition research. Epidemiology clearly shows that higher intakes, compared to lower intakes, leads to a risk reduction for a range of diseases, including cardiovascular disease and colon cancer.

And based on this epidemiological evidence, most dietary guidelines recommend dietary patterns that provide adults with 30-35g of dietary fiber per day.

However, what do we know about intakes beyond this?

Do we continue to see benefit in a linear fashion? Is there a ceiling to benefit? At what level would we see “optimal” benefit or the greatest magnitude of risk reduction?

The ability to answer such questions is hampered by the fact it’s difficult to find cohort studies where the “high” fiber level is high enough to relate to this issue. However, there have been some controlled studies looking specifically at “very high” intakes, i.e. those far above current recommendations. In addition, there are some populations where habitual dietary intake gives a fiber intake far above the typical intakes in Western cohorts.

So in this episode we go through this data to try to see what we can conclude about this fascinating question of ‘what are the health effects at very high fiber intakes?’

Co-hosts for this Episode

Dr. Alan Flanagan has a PhD in nutrition from the University of Surrey, where his doctoral research focused on circadian rhythms, feeding, and chrononutrition.

This work was based on human intervention trials. He also has a Masters in Nutritional Medicine from the same institution.

Dr. Flanagan is a regular co-host of Sigma Nutrition Radio. He also produces written content for Sigma Nutrition, as part of his role as Research Communication Officer.

Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.

Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.


  • Epidemiology suggestive of benefit to more?
    • Pereira et al., 2004
    • Aune et al., 2011
    • Reynolds et al., 2020
  • Diet swap in African Americans & rural Africans
  • Very high fiber & blood lipids
  • Very high fiber & hyperlipidemia
  • Very high fiber & diabetes
  • Potential detrimental impacts of very high fiber

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  1. Hey Danny, The detailed study notes don’t seem to be loading correctly

  2. This is an interesting podcast, in particular how it relates to me since my intake is over 70 grams of fiber daily being whole food-plant based. Originally, I started this food program to fix my serum cholesterol and it dropped from 210 mg/dl (high being over 200) to 120, which some claim is virtually heart attack proof. The LDL went from 120 (high being over 100) to about 65, again, virtually heart attack proof by some claims. It just so happened to fix my high blood pressure, resting heart rate, and weight. I’m on Mcdougall Starch Solution.

    It’s been 6 years and the only measure which is high is just slightly, being blood pressure at 130/90. I need to exercise more and reduce salt intake a bit.

    The different between the highest and lowest groups of fiber intake have a dramatic difference in mortality risk. It is something that certainly affect individuals who eat very low amounts of grain, beans and other starches, if they happen to be on something like a standard omnivore low carb diet.

    My typical foods include whole wheat pasta and black beans with cayenne pepper, or whole wheat bread: yeast, flour and a small amount of sugar plus salt. Then, I also eat bananas, kale and carrots, but at times have eaten baked potato slices, white or whole grain rice.

    Thanks again for the great science podcast.

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