Food · 4 min read ·

Fibre: modest and underrated

Fibre has hardly any calories or vitamins, yet it is one of the best-studied parts of the diet. How much to eat and what it can do.

In a nutshell

1How much fibre

EFSA and WHO recommendation 25 g EFSA considers 25 g of fibre a day an adequate intake for adults; WHO recommends at least 25 g of naturally occurring fibre and 400 g of vegetables and fruit a day. Adults in Europe eat 16–29 g on average.1,2

The main sources are whole grains, pulses, fruit, vegetables and potatoes.1 More in the articles Side dishes, Vegetables and Fruit.

2What it does for health

Moderate evidence −15 to 30% A series of summaries of 185 prospective studies and 58 clinical trials: people with the highest fibre intake had 15–30% lower mortality and less heart disease, stroke, type 2 diabetes and colorectal cancer than those with the lowest. Risk fell most at 25–29 g a day, and even higher intakes might protect more.3

In clinical trials, people who ate more fibre had lower body weight, blood pressure and cholesterol.3

3Constipation and digestion

Moderate evidence 66% / 41% A summary of 16 randomised trials with 1,251 people with constipation: fibre supplements helped 66% of people, control treatment 41%. Psyllium worked best, at doses above 10 g a day taken for at least 4 weeks. But fibre increased flatulence.4

That is why it makes sense to add fibre gradually.

4Cholesterol and weight

Moderate evidence −0.33 mmol/L A summary of 28 randomised trials with 1,924 people: about 10 g of psyllium a day lowered LDL cholesterol by 0.33 mmol/L.5
Weak evidence −0.33 kg A summary of 62 studies: viscous (gel-forming) fibre reduced weight by 0.33 kg even without calorie restriction. The effect is small and results varied between studies.6

What to take from this

Sources

Written on , based on studies available at that date. Newer research may change the conclusions.

  1. EFSA (2017). Dietary Reference Values for nutrients: Summary report. EFSA Supporting Publications 14(12):e15121. doi.org/10.2903/sp.efsa.2017.e15121
  2. World Health Organization (2023). WHO updates guidelines on fats and carbohydrates (press release). who.int
  3. Reynolds A. et al. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet 393:434–445. doi.org/10.1016/S0140-6736(18)31809-9
  4. van der Schoot A. et al. (2022). The effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 116:953–969. doi.org/10.1093/ajcn/nqac184
  5. Jovanovski E. et al. (2018). Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 108:922–932. doi.org/10.1093/ajcn/nqy115
  6. Jovanovski E. et al. (2020). Can dietary viscous fiber affect body weight independently of an energy-restrictive diet? A systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 111:471–485. doi.org/10.1093/ajcn/nqz292

This is general information and does not replace a doctor or dietitian. If you have long-term constipation, blood in your stool or a bowel disease, see a doctor.