Most adults over 75 eat far less fibre than their body needs — often less than half the recommended 25–30 g per day. The right foods, introduced gradually, support regular bowel function, a healthy gut, lower cholesterol and steadier blood sugar. The key is a steady increase, not a sudden one.
The part of plant food your body cannot digest
Dietary fibre is the collective name for the indigestible parts of plant foods — cell walls, husks, seeds and gums — that pass through the small intestine largely intact and reach the large intestine (colon) in an undigested form. Unlike protein, fat or starch, fibre provides very little energy. Its value lies entirely in what it does along the way.
- Soluble fibre — dissolves in water to form a gel. Slows digestion, lowers LDL cholesterol and smooths the rise in blood sugar after meals. Found in oats, legumes, apples and psyllium.
- Insoluble fibre — does not dissolve. Adds bulk to stools and speeds their passage through the bowel, reducing constipation. Found in wheat bran, wholegrain bread, vegetables and nuts.
- Prebiotic fibre — a subset of soluble fibre that feeds beneficial bacteria in the colon. Includes inulin and fructooligosaccharides, found in onions, garlic, leeks and legumes.
Most plant foods contain a mixture of both soluble and insoluble fibre, so eating a varied diet provides a useful balance. No single food delivers everything; variety is the most important principle.
Why fibre matters more — and is harder to get — after 75
Several changes that come with ageing make adequate fibre intake both more important and more difficult. Gut motility (the movement of food through the digestive tract) slows with age, partly due to reduced muscle tone in the bowel wall and changes in the nerves that control it. Constipation affects an estimated 30–40% of adults over 65, and reduced fluid intake — itself common in older age due to a blunted thirst response — compounds the problem.
At the same time, appetite tends to decrease, meals become smaller, and some people reduce fruit and vegetable intake due to chewing difficulties, cost, or the effort of cooking for one. The result is that fibre intake often falls significantly below the recommended target.
A 2024 analysis of the UK National Diet and Nutrition Survey found that mean dietary fibre intake in older adults was just 18.3 g per day — barely half the recommended 30 g — with fewer than 6% of older adults meeting their target.[1]
The good news is that the benefits of increasing fibre intake are measurable at any age. Research consistently shows that even modest increases — from 15 g to 25 g per day — produce meaningful improvements in bowel regularity, cholesterol and blood sugar control.
What each type of fibre does for your health
Different fibres act in different parts of the body. Select each one below to understand what it does and which foods provide it.
Soluble fibre dissolves in water in the gut to form a thick gel, which slows the emptying of the stomach and the absorption of glucose into the bloodstream. This blunts sharp rises in blood sugar after meals — particularly useful for the many older adults managing type 2 diabetes or pre-diabetes. The gel also binds to cholesterol and bile acids in the intestine, carrying them out of the body and lowering LDL ("bad") cholesterol.
A systematic review and meta-analysis published in PMC found that soluble fibre supplementation significantly reduced fasting blood glucose and HbA1c in adults with type 2 diabetes across 28 randomised controlled trials.[3] Beta-glucan, the soluble fibre in oats and barley, has a well-established cholesterol-lowering effect confirmed by multiple regulatory bodies worldwide.
Target: aim for at least 5–10 g of soluble fibre per day, equivalent to a bowl of porridge plus one piece of fruit.
Insoluble fibre does not dissolve but absorbs water as it moves through the large bowel, swelling to add bulk to stools and stimulating the muscular contractions that propel waste through the colon. This is the fibre most directly responsible for preventing constipation — a condition affecting a large proportion of adults over 70.
Research published in PMC on nutritional therapy and gastrointestinal motility in older adults confirmed that increased insoluble fibre intake, combined with adequate fluid intake, significantly reduced constipation and improved stool frequency.[2] Crucially, insoluble fibre only works well when fluid intake is sufficient — at least 6–8 cups of water or other drinks daily.
Important: always increase insoluble fibre gradually and drink more water alongside it to avoid worsening bloating.
Prebiotic fibres are fermented by the beneficial bacteria — particularly Bifidobacterium and Lactobacillus species — that live in the large intestine. Fermentation produces short-chain fatty acids (SCFAs) such as butyrate, which nourish the lining of the colon, reduce inflammation and support immune function. The diversity and health of the gut microbiome tends to decline with age, making prebiotic fibre particularly valuable for older adults.
A 2024 study in PMC confirmed that a dietary pattern rich in prebiotic fibre was inversely associated with constipation in a large representative sample of US adults, and that gut microbiota diversity mediated much of this effect.[4] Small portions of prebiotic foods daily are more effective than occasional large servings.
Note: prebiotic fibre can cause gas and bloating if introduced too quickly. Start with half a serving per day and increase slowly over 2–3 weeks.
Resistant starch is a type of starch that resists digestion in the small intestine and behaves like a fermentable fibre in the colon. It is found naturally in foods such as unripe bananas, lentils and whole grains, and it forms in cooked starchy foods — potatoes, pasta and rice — that have been allowed to cool. Cooling causes the starch to re-crystallise into a form that is harder to digest.
Resistant starch has been shown to improve insulin sensitivity and reduce post-meal blood sugar spikes. A systematic review in PMC found that dietary fibre, including resistant starch, was associated with a meaningful reduction in HbA1c and fasting glucose in people with or at risk of type 2 diabetes.[3] Eating cooled potato salad, cold cooked pasta or leftover rice is a practical way to add resistant starch without any additional preparation.
Practical tip: cook potatoes or rice the day before, refrigerate overnight, then reheat gently — the resistant starch content remains higher even after reheating.
Higher dietary fibre intake — particularly cereal and fruit fibre — is one of the most consistently protective dietary factors against cardiovascular disease. The mechanisms include reduced LDL cholesterol (via soluble fibre binding bile acids), lower blood pressure, reduced systemic inflammation, and improved blood vessel function. These effects are additive; no single food provides all of them.
A study in the Cardiovascular Health Study cohort of adults aged 65 and over found that cereal fibre intake was associated with significantly lower levels of inflammatory markers including C-reactive protein and interleukin-6, and that higher cereal fibre intake was independently associated with lower incidence of cardiovascular disease over 10 years of follow-up.[5] A 2025 open-access meta-analysis confirmed that dietary fibre intake was inversely associated with all-cause and cardiovascular mortality across a broad range of intakes.[6]
Even a modest daily increase of 7 g of fibre — one extra bowl of oats or a serving of lentils — is associated with a 9% reduction in cardiovascular disease risk.
What to put on your plate
The most effective strategy is to include high-fibre foods at every meal rather than relying on one or two sources. Soft-cooked or well-prepared options below are chosen with chewing comfort and ease of solo preparation in mind.
Making it work in a solo kitchen
Increase fibre slowly — one step per week
The most common reason people abandon a higher-fibre diet is digestive discomfort: bloating, wind and loose stools that can occur when fibre intake rises too quickly. The gut microbiome needs time to adjust. A safe, comfortable approach is to add just one additional fibre-rich food per week — for example, switching from white to wholemeal bread in week one, adding a serving of lentils to soup in week two, and including a daily piece of fruit in week three.
Drink more water alongside fibre
Insoluble fibre absorbs water as it moves through the bowel. Without adequate fluid, it can harden rather than soften stools and make constipation worse. Aim for at least 6–8 cups of fluid daily — water, herbal teas, diluted juice and soups all count. A practical prompt is to have a glass of water with every meal and a cup of herbal tea mid-morning and mid-afternoon.
Use tinned and frozen foods without compromise
Fresh produce is not necessary to meet fibre targets. Tinned legumes (chickpeas, kidney beans, lentils), frozen vegetables and tinned fruit in juice are equally nutritious and far more practical for a solo household. A tin of lentil soup, a handful of frozen peas added to any dish, or tinned peaches on porridge are all simple, low-waste ways to raise daily fibre intake.
A practical way to reach 25 g of fibre without counting: a bowl of porridge at breakfast (+4 g), two slices of wholemeal bread at lunch (+5 g), a serving of lentils or beans at dinner (+8 g), two pieces of fruit during the day (+5 g), and a small handful of nuts (+2 g). That is approximately 24 g with minimal effort.
If you have irritable bowel syndrome (IBS), inflammatory bowel disease (Crohn's disease or ulcerative colitis), a history of bowel obstruction, or are taking medications such as certain diabetes drugs or blood thinners, please discuss changes to your fibre intake with your GP or a registered dietitian before making them. In some conditions, high-fibre foods need to be introduced under specific guidance. Fibre supplements (such as psyllium) should also be discussed with your doctor if you are on regular medication, as they can affect drug absorption timing.
Foods and habits that reduce fibre intake and gut health
- Refined white grains — white bread, white rice and standard pasta have had their bran and germ removed, eliminating most of their fibre. Switching to wholegrain equivalents is one of the simplest changes with the most impact.
- Ultra-processed snack foods — biscuits, crackers, crisps and packaged cakes are low in fibre and high in sodium and saturated fat, often replacing more nutritious fibre-rich foods in the diet.
- Inadequate fluid intake — not drinking enough water with a higher-fibre diet is the leading cause of fibre-related digestive discomfort. Dehydration stiffens the stool, negating the benefits of insoluble fibre.
- Peeling all fruit and vegetables — much of the insoluble fibre in apples, pears, potatoes and carrots sits in or just under the skin. Washing and eating the skin where possible is an easy way to retain fibre that is commonly discarded.
Dietary fibre at a glance
| Fibre type | Main health benefit | Best food sources |
|---|---|---|
| Soluble (beta-glucan, pectin) | Lowers LDL cholesterol; smooths blood sugar rises | Oats, barley, apples, lentils, psyllium |
| Insoluble (cellulose, bran) | Adds stool bulk; prevents constipation | Wholemeal bread, bran, root vegetables, nuts |
| Prebiotic (inulin, FOS) | Feeds gut bacteria; reduces inflammation | Onions, garlic, leeks, asparagus, chickpeas |
| Resistant starch | Improves insulin sensitivity; feeds colon cells | Cooled potato or rice, lentils, unripe bananas |
Scientific sources
- Gibson R, et al. (2024). Exploring UK older adults' dietary fibre consumption habits and associated factors: a national diet and nutrition survey perspective. British Journal of Nutrition (PMC Open Access). View article ↗
- Volkert D, et al. (2023). The Impact of Nutritional Therapy on Gastrointestinal Motility in Older Adults. Nutrients (PMC Open Access). View article ↗
- Jovanovski E, et al. (2020). Effects of soluble fiber supplementation on glycemic control in adults with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials. Clinical Nutrition. View article ↗
- Wu Y, et al. (2025). Association of the newly proposed dietary index for gut microbiota and constipation: a cross-sectional study from NHANES. BMC Gastroenterology (PMC Open Access). View article ↗
- Mozaffarian D, et al. (2022). Intake and Sources of Dietary Fiber, Inflammation, and Cardiovascular Disease in Older US Adults. Journal of the American Heart Association (PMC Open Access). View article ↗
- Zhang Y, et al. (2025). Dietary Fiber Intake Was Inversely Associated with All-Cause Mortality but Not with Cancer and Cardiovascular Disease Mortalities in the US. Nutrients (PMC Open Access). View article ↗
- Reynolds A, et al. (2020). Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses. PLOS Medicine (PMC Open Access). View article ↗