Dietary fibre is one of the few nutrients most Australians hear about constantly and still don’t get enough of. National survey data suggests more than 7 in 10 Australian adults fall short of the minimum recommended intake, and fewer than 1 in 5 meet the higher target linked to long-term disease prevention. This shortfall, sometimes referred to as the ‘fibre gap’, has significant consequences for gut function and longer-term risk of heart disease, type 2 diabetes and some cancers.
Fibre represents the part of plant foods our digestive enzymes can’t break down. Some (soluble) types dissolve in water and slow digestion, helping regulate blood glucose and cholesterol; whilst others stay largely intact and add bulk that keeps the bowel moving (insoluble). Most wholefoods contain a mix of both, which is why whole grains, legumes, vegetables and fruit remain the main recommended sources within a balanced diet.
Adequate daily intake
Australia’s Nutrient Reference Values set an Adequate Intake (AI) of 25 grams per day for women and 30 grams per day for men to support normal gastrointestinal function in otherwise healthy adults. A higher Suggested Dietary Target (SDT) to specifically target chronic disease risk is additionally set at 28 g/d for women and 38 g/d for men.
Analysis of the 2011-12 national nutrition survey data, led by researchers at Macquarie University, found that the median fibre intake for Australian adults sat at around 21 grams per day – below the AI and well short of the SDT. Based on these figures more than 7 in 10 adults don’t meet the AI, whilst over 4 in every 5 fail to meet the SDT. Intakes tend to be lowest among adolescents, young adults, males (once adjusted for total energy intake) and those with lower socio-economic status.
Why we aren’t meeting the requirements
The same research compared those with the highest fibre intakes to those with the lowest, and the differences weren’t attributed to restricted eating but rather came down to food choices. Higher fibre consumers ate roughly 2 more serves of grains and 2 more serves of fruit per day, close to 4 times the vegetable serves and 6-8 times more wholegrain foods than lower consumers. Their diets contained 40% less discretionary food. Much of the gap could be attributed to choices within familiar categories: selecting wholegrain or mixed-grain breads over white, higher-fibre breakfast cereals and the presence of legumes in everyday meals.
Why it matters
A large 2019 series of systematic reviews and meta-analyses published in The Lancet found that higher fibre intake was associated with a lower risk of coronary heart disease, stroke, type 2 diabetes and colorectal cancer, alongside lower all-cause and cardiovascular mortality. These reductions in risk became more pronounced as intake increased across the 25-29 gram range and beyond, suggesting many Australians whose consumption falls below the AI threshold may still be considerably short of where the greatest protective benefit is seen. As with most nutrition evidence of this nature, these are associations drawn from population studies rather than evidence of individual outcomes, and fibre likely represents just one pillar within a broader dietary matrix that may need attention.
Increasing your intake
Closing the fibre gap is often more about small substitutions rather than an entire dietary overhaul. The consumption data above suggests choosing wholegrain or fibre enriched options, adding legumes to meals and consuming fruit with the peels intact may be all you need to push your intake into a healthier zone. For anyone looking to meaningfully increase their intake, doing so gradually and concurrently with adequate water intake can help avoid digestive discomfort, whilst those with existing gastrointestinal issues may wish to consult their doctor or allied health professional before making any major changes.
Small, consistent choices at the everyday food level are what separate the highest fibre consumers from everyone else, which means the fibre gap, unlike many more challenging nutrition targets, may be a genuinely achievable one to close.
References
Fayet-Moore F, Cassettari T, Tuck K, McConnell A, Petocz P. Dietary Fibre Intake in Australia. Paper I: Associations with Demographic, Socio-Economic, and Anthropometric Factors. Nutrients. 2018;10(5):599. https://doi.org/10.3390/nu10050599
Fayet-Moore F, Cassettari T, Tuck K, McConnell A, Petocz P. Dietary Fibre Intake in Australia. Paper II: Comparative Examination of Food Sources of Fibre among High and Low Fibre Consumers. Nutrients. 2018;10(9):1223. https://doi.org/10.3390/nu10091223
National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand: Dietary Fibre. Eat For Health, Australian Government. https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/dietary-fibre
Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. 2019;393(10170):434-445. https://doi.org/10.1016/S0140-6736(18)31809-9
Written by Helena Setio Luongo, a University of Sydney-trained nutritionist and exercise scientist, and Scientific Affairs Manager at TAIK Health.
