Articles · Nutrients
Fibre: the nutrient most of us are missing
What fibre does, how much you need (probably more than you eat), and an ordinary day of meals that gets there without a single supplement.
· 4 min read
Quick: name a nutrient most people don't get enough of. Vitamin D? Iron? Both good guesses. But the gap that's widest for the most people is a humbler one: fibre. Why does something your body can't even digest matter so much?
What is fibre, anyway?
Fibre is the part of plant foods that your small intestine can't break down: the skins, seeds, husks and cell walls of grains, beans, vegetables, fruit, nuts and seeds. Instead of being absorbed, it travels on to the large intestine, where it does three useful jobs:
- It keeps things moving. Fibre holds water and adds bulk, which helps prevent constipation.
- It feeds your gut bacteria. They ferment some kinds of fibre into short-chain fatty acids, which nourish the gut lining.
- It slows things down. Soluble fibre, as in oats, beans and apples, forms a gel that slows how fast sugar enters the blood and helps lower LDL cholesterol.
Think about it: How many of yesterday's meals had whole grains, beans, vegetables or fruit in them? All three meals, or one?
How much do you need?
- In the UK, adults are advised to eat 30 g a day. Most eat about 20 g.
- In the United States, the advice is about 14 g for every 1,000 kcal: roughly 25 g a day for women and 38 g for men under 50. Most adults get around 15 g.
A large review published in The Lancet in 2019 pulled together 185 long-term studies and 58 trials. People who ate the most fibre had 15–30% lower rates of heart disease, stroke, type 2 diabetes and bowel cancer, and lower death rates overall, than those who ate the least. The benefits were greatest at 25–29 g a day, and eating more than that may help further.
The Harvesters, Pieter Bruegel the Elder, 1565, The Metropolitan Museum of Art, New York. Harvest time in 1565: golden wheat cut by hand, and a lunch break in the shade of a pear tree. Their bread was made from much less refined flour than most of ours, so it carried far more fibre. Public domain · Wikimedia CommonsWhere's the fibre?
Roughly how much these portions carry:
- A cup of cooked lentils: 15 g. Chickpeas or black beans: 12–15 g.
- A cup of raspberries: 8 g. A pear: 5–6 g. An apple, with its skin: 4 g.
- A cup of cooked broccoli: 5 g. A baked potato with its skin: about 4 g.
- A bowl of porridge (40 g of oats): 4 g. Half an avocado: 6–7 g.
- A slice of wholemeal bread: 2 g, against under 1 g for white.
- A small handful of almonds: 3–4 g. A tablespoon of chia seeds: 4 g.
A 30-gram day, without trying too hard
- Breakfast: porridge with a handful of raspberries (about 8 g).
- Lunch: lentil soup with a slice of wholemeal bread (about 10 g).
- Snack: an apple (4 g).
- Dinner: a baked potato with its skin, plus broccoli (about 9 g).
That's around 31 g, from foods most kitchens already have.
Try this: Go up gradually, over a couple of weeks, and drink enough water: a sudden jump in fibre can leave you bloated and gassy while your gut bacteria catch up.
Think about it: Which one swap could you make this week: white bread to wholemeal, juice to whole fruit, or adding a can of beans to a sauce?
Quick quiz
Why can fibre help lower blood cholesterol?
Soluble fibre, as in oats, beans and apples, forms a gel in the gut that helps carry cholesterol out of the body.
Which has more fibre: a glass of apple juice or an apple?
The apple, with its skin. Juicing leaves most of the fibre behind.
What's the best way to start eating more fibre without discomfort?
Increase it gradually over a couple of weeks and drink enough fluid.
Sources
General information, not medical advice. If you have a health condition, are pregnant or take medication, ask a doctor or dietitian what is right for you.