Fiber

Last update: 18 December 2020

This page explores the essentiality of dietary fiber. If you have any interesting studies on the topic, please share. There’s a chance I haven’t looked at it. Contact information is on the About Me page.

While dietary fiber may be helpful in weight loss8 (as one would expect from consuming mostly indigestible material) it is not a complety benign substance, and its associations may almost completely stem from its weight reduction properties. Contrary to common claims:

  • You don’t need it to evacuate1.
  • Additional fiber, in the form of supplements or normal foods, can be helpful in constipation, but it’s not a panacea, and the evidence is quite heterogenous3,9,10,11,12,13.
  • Fiber can cause constipation and other gastrointestinal problems1,2,10.
  • Fiber isn’t essential for short-chain fatty acid production in the bowel4.
  • Eating more fiber doesn’t reduce all-cause mortality5.
  • Fiber doesn’t prevent colon cancer6.
  • Fiber doesn’t prevent heart disease7.

References

  1. Ho et al, “Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms”, World J Gastroenterol. 2012 Sep 7; 18(33): 4593–4596.
  2. Bijkerk et al, “Systematic review: the role of different types of fibre in the treatment of irritable bowel syndrome.”, Aliment Pharmacol Ther. 2004 Feb 1;19(3):245-51.
  3. Ornstein et al, “Are fibre supplements really necessary in diverticular disease of the colon? A controlled clinical trial.”, Br Med J (Clin Res Ed). 1981 Apr 25;282(6273):1353-6.
  4. David et al, “Diet rapidly and reproducibly alters the human gut microbiome.”, Nature. 2014 Jan 23;505(7484):559-63.
  5. Burr et al, “Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART).”, Lancet. 1989 Sep 30;2(8666):757-61.
  6. Asano et al, “Dietary fibre for the prevention of colorectal adenomas and carcinomas.”, Cochrane Database Syst Rev. 2002;(2):CD003430.
  7. Ness et al, “The long-term effect of dietary advice in men with coronary disease: follow-up of the Diet and Reinfarction trial (DART).”, Eur J Clin Nutr. 2002 Jun;56(6):512-8.
  8. Lancet. 2019 Feb 2;393(10170):434-445. doi: 10.1016/S0140-6736(18)31809-9. Epub 2019 Jan 10. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Reynolds A1, Mann J2, Cummings J3, Winter N4, Mete E4, Te Morenga L5.
  9. Yang J, Wang HP, Zhou L, Xu CF. Effect of dietary fiber on constipation: a meta analysis. World J Gastroenterol. 2012;18(48):7378-7383. doi:10.3748/wjg.v18.i48.7378
  10. Christodoulides S, Dimidi E, Fragkos KC, Farmer AD, Whelan K, Scott SM. Systematic review with meta-analysis: effect of fibre supplementation on chronic idiopathic constipation in adults. Aliment Pharmacol Ther. 2016 Jul;44(2):103-16. doi: 10.1111/apt.13662. Epub 2016 May 12. PMID: 27170558.
  11. Suares NC, Ford AC. Systematic review: the effects of fibre in the management of chronic idiopathic constipation. Aliment Pharmacol Ther. 2011 Apr;33(8):895-901. doi: 10.1111/j.1365-2036.2011.04602.x. Epub 2011 Feb 20. PMID: 21332763.
  12. Woo HI, Kwak SH, Lee Y, Choi JH, Cho YM, Om AS. A Controlled, Randomized, Double-blind Trial to Evaluate the Effect of Vegetables and Whole Grain Powder That Is Rich in Dietary Fibers on Bowel Functions and Defecation in Constipated Young Adults. J Cancer Prev. 2015;20(1):64-69. doi:10.15430/JCP.2015.20.1.64
  13. Rao SS, Yu S, Fedewa A. Systematic review: dietary fibre and FODMAP-restricted diet in the management of constipation and irritable bowel syndrome. Aliment Pharmacol Ther. 2015 Jun;41(12):1256-70. doi: 10.1111/apt.13167. Epub 2015 Apr 22. Erratum in: Aliment Pharmacol Ther. 2015 Aug;42(4):490. PMID: 25903636.