Dietary fibre is the part of plant food that the body cannot break down into sugar, so it passes through the gut largely undigested.1 The importance of dietary fibre comes from what it does along the way, and from how little of it most adults eat. The NHS says adults should aim for 30 g a day, while the average adult manages about 20 g.2 WHO sets its own minimum for adults at 25 g of naturally occurring fibre a day.3
Fibre for gut health
Fibre works in the gut in more than one way. Harvard's Nutrition Source explains that insoluble fibre, the kind that does not dissolve in water, can help food move through the digestive system and helps prevent constipation.1 Whole-wheat foods, especially wheat bran, along with legumes, leafy greens, nuts, seeds and fruit eaten with the skin, are among the sources it lists. Some fibres are also fermentable, which means bacteria in the gut break them down and use them as food.1
The NHS sums up the everyday effect: choosing foods with fibre can help with your digestion and prevent constipation.2 Harvard's page adds a practical point. A sudden, large rise in fibre can cause bloating and cramping, so it suggests raising fibre gradually and drinking more fluids as you do.1
Fibre and heart health
The NHS says eating plenty of fibre is associated with a lower risk of heart disease and stroke, as well as type 2 diabetes and bowel cancer.2 Harvard's Nutrition Source describes one route for the heart. Soluble fibre, the kind that dissolves in water, can help lower blood cholesterol.1 Oats, beans, lentils, nuts, chia seeds and apples are among the foods Harvard lists for this kind of fibre.1
That list fits an Indian kitchen well, since dal, rajma and chana all count as beans and lentils. ICMR-NIN's Dietary Guidelines for Indians, 2024, describe pulses as low-fat, high-fibre foods.4
Fibre and blood sugar
Harvard describes fibre as helping to regulate the body's use of sugars, which helps keep hunger and blood sugar in check.1 Soluble fibre takes up water in the gut and forms a gel that slows digestion. This may help prevent blood sugar from surging after a meal.1
WHO's 2023 guidance points the same way for carbohydrate in general. It says the carbohydrate in your diet should come mainly from whole grains, vegetables, fruit and pulses, the foods that carry fibre naturally.3
The grain you choose makes a real difference here. ICMR-NIN's Indian Food Composition Tables list whole-wheat atta at 11.36 g of dietary fibre in 100 g, against 2.76 g for refined flour, or maida.5 Bajra and ragi come close to atta, at about 11 g each.5
Reaching 30 g of fibre in a day
The NHS calls a food high in fibre when it has 6 g or more in every 100 g, which is a handy figure to look for on a packet.2 Fresh foods come without a label, so USDA's food tables are a good guide to what a normal portion gives.
| Food | Portion | Fibre |
|---|---|---|
| Oats, dry6 | 40 g | about 4 g |
| Chickpeas (chana), boiled7 | 150 g | about 11 g |
| Guava, raw8 | 100 g | about 5 g |
A bowl of oats at breakfast, a katori of chana at lunch and a guava in the afternoon come to about 20 g between them. That is two-thirds of the NHS figure and four-fifths of WHO's. Two rotis made from 60 g of atta would add close to 7 g more, taking the day past 25 g before any vegetables or nuts.
Fibre in a Horlicks Protein sachet or milkshake
A Horlicks Protein sachet lists 4 g of prebiotic fibre next to its 24 g of protein. The sachet is 36 g, meant for 200 ml of cold water or milk. The Horlicks Protein milkshake needs no mixing, and each 240 ml bottle lists 20 g of ultra-filtered milk protein, with 3.5 g of fibre.
Either one adds those grams to the day's fibre count, and against the NHS's 30 g, a sachet's 4 g is a little over an eighth of the day. On the food day above, with the two rotis included, a sachet would take the total from about 27 g to about 31 g. Most of that fibre still comes from grains, pulses and fruit.
To sum up, dietary fibre matters because it passes through the body largely undigested and does useful work on the way. In the gut, it helps digestion and helps prevent constipation, and some fibres feed gut bacteria. For the heart, eating plenty of fibre is linked with a lower risk of heart disease and stroke, and soluble fibre can help lower blood cholesterol. For blood sugar, it slows digestion and helps keep sugar levels steadier after meals. Adults need about 30 g a day by the NHS figure, or at least 25 g by WHO's, and most of it comes from atta, millets, pulses, oats and fruit.
Sources
1. Harvard T.H. Chan School of Public Health. The Nutrition Source, Fiber. https://nutritionsource.hsph.harvard.edu/carbohydrates/fiber/
2. NHS. How to get more fibre into your diet. https://www.nhs.uk/live-well/eat-well/digestive-health/how-to-get-more-fibre-into-your-diet/
3. World Health Organization. WHO updates guidelines on fats and carbohydrates, 17 July 2023. https://www.who.int/news/item/17-07-2023-who-updates-guidelines-on-fats-and-carbohydrates
4. ICMR-National Institute of Nutrition. Dietary Guidelines for Indians, 2024. https://nin.res.in/dietaryguidelines/pdfjs/locale/DGI_2024.pdf
5. ICMR-National Institute of Nutrition. Indian Food Composition Tables, 2017. https://www.nin.res.in/ebooks/IFCT2017.pdf
6. USDA FoodData Central. Cereals, oats, regular and quick, not fortified, dry. FDC 173904. https://fdc.nal.usda.gov/food-search/?query=173904&type=SR%20Legacy
7. USDA FoodData Central. Chickpeas (garbanzo beans, bengal gram), mature seeds, cooked, boiled, without salt. FDC 173757. https://fdc.nal.usda.gov/food-search/?query=173757&type=SR%20Legacy
8. USDA FoodData Central. Guavas, common, raw. FDC 173044. https://fdc.nal.usda.gov/food-search/?query=173044&type=SR%20Legacy