Millions of people are at risk of an early death because they do not eat enough fibre, according to a major study.
A review commissioned by the World Health Organisation found that people who get plenty of fibre in their diet cut their risk of early mortality by up to a third.
They also cut their risk of a heart attack, stroke, type two diabetes or bowel cancer by up to a quarter.
Yet the vast majority of adults in Britain – around 91 per cent – eat less than the recommended daily amount. Similar figures exist in the US.
The findings are a blow for trendy low-carb diets, which have boomed in popularity in recent years and have also driven down fibre intake.
Fibre – sometimes referred to as ‘roughage’ – is vital for digestion and helps keep people feeling fuller for longer.
It is found in high levels in fruit, vegetables, and cereals, as well as bread and pasta made with wholegrain and wholewheat.
A review commissioned by the World Health Organisation found that people who get plenty of fibre – found in wholemeal bread – in their diet cut their risk of early mortality by up to a third
But the rise of processed food – which often cuts out much of the fibre in raw ingredients – has meant people often get too little of these ingredients.
Researcher Professor John Cummings, of the University of Dundee, said the new review – published in the Lancet medical journal – will have a major impact.
‘This is a defining moment in the fibre story,’ he said.
‘The work that we have done means we have enough evidence from population studies, human experimental work and the biochemistry and physiological of fibre to be confident of the clear benefits to health.
‘Fibre has come of age as a unique and essential nutrient.’
His team combined the results of more than 230 previous studies, involving 215,000 people.
They found people who ate more than 30g a day of fibre – the amount recommended by Public Health England – were 24 per cent less likely to die early from any cause than people who ate 8g a day.
And for those who ate more than 35g the risk dropped by over a third.
To make sure people get enough fibre, potatoes, pasta, bread and other starchy carbohydrates – traditional foods which are dropping out of fashion – should form the main components of a healthy diet, health officials say.
To eat 30g of fibre people should eat five portions of fruit and veg per day, as well as the equivalent of two wholemeal breakfast cereal biscuits, two thick slices of wholemeal bread and a large jacket potato with the skin on.
But, critically, people should choose wholemeal options in order to get the most nutrition out of the carbohydrates they eat.
HOW TO UNDERSTAND NUTRITIONAL INFORMATION ON YOUR FOOD
The vast majority of packaged foods in the UK come with nutritional information printed on the label.
The main things to look for are fat, saturated fat, salt (which may be called sodium), fibre and sugar – which is often listed as ‘of which sugars’ beneath carbohydrates.
Generally speaking, foods with higher fibre and lower saturated fat, salt and sugar are healthier.
Some supermarkets also label nutritional value with a traffic light system, in which more green points to healthier food.
The NHS advice on what is high or low is as follows:
High: more than 17.5g of fat per 100g
Low: 3g of fat or less per 100g
An adult’s recommended daily allowance (RDA) of fat is around 70g.
High: more than 5g of saturated fat per 100g
Low: 1.5g of saturated fat or less per 100g
An adult’s RDA of saturated fat is around 20g.
Sugars (aka of which sugars)
High: more than 22.5g of total sugars per 100g
Low: 5g of total sugars or less per 100g
An adult’s RDA of sugars is around 90g.
Salt (aka sodium)
High: more than 1.5g of salt per 100g (or 0.6g sodium)
Low: 0.3g of salt or less per 100g (or 0.1g sodium)
An adult’s RDA of salt is 6g or less.
Source: NHS Choices
Professor Jim Mann, of the University of Otago in New Zealand, who also worked on the new paper, said: ‘Our findings provide convincing evidence for nutrition guidelines to focus on increasing dietary fibre and on replacing refined grains with whole grains.
‘Fibre-rich whole foods that require chewing and retain much of their structure in the gut increase satiety and help weight control and can favourably influence lipid [cholesterol] and glucose levels.’
His team found for every 8g increase of dietary fibre eaten per day, deaths decreased by between 5 and 27 per cent.
They said consuming 25g to 29g each day was adequate but more than 30g would give greater protection. Protection against stroke, and breast cancer also increased.
Experts welcomed the findings. Professor Kevin Whelan of King’s College London, said: ‘The challenge is that many people in the UK do not eat this amount of fibre.
‘The major sources of fibre in the UK diet are cereals – bread, pasta, rice, breakfast cereal – and vegetables and fruit.
‘People should consider ways of increasing fibre intake through changing food preparation methods – eg. not peeling potatoes – switching to wholegrain cereals and replacing sugary snacks with fruits, vegetables, nuts and seeds.’
Dr Ian Johnson of the Quadram Institute Bioscience in Norwich, said: ‘The sheer volume of evidence, together with the consistency of findings from both observational studies and randomised controlled trials, shows that we can now be very confident that a high consumption of fibre from all sources, and particularly from whole-grain cereals, provide significant protection against the common diseases of later life that now place considerable strains on the NHS.
‘It is also worrying that otherwise healthy consumers who try to follow popular diets low in carbohydrate will find it very difficult to achieve a healthy level of fibre intake.’
Professor Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said: ‘I think this is an important paper which highlights better than before the potential value to health of higher dietary fibre intake.
Millions in Britain are at risk of an early death because they do not eat enough fibre (stock)
‘However, as with the vast majority of nutritional data, most of the evidence comes from observational studies and one has to be cautious about conclusions reached given the unavoidable biases they contain.
‘That noted, this paper importantly also includes risk factor data from trials and the reductions in weight and other known causal risk factors such as blood pressure, cholesterol, etc seen with higher fibre (whole grain) diets, although modest do support the overall findings linking more fibre in the diet to less heart disease, diabetes, cancers, and potentially longer life.
‘So I tend to believe the overall findings are directionally true and so concur with the authors conclusions when they write ‘recommendations to increase dietary fibre intake and to replace refined grains with whole grains is expected to benefit human health.’
Prof. Nita Forouhi, MRC Epidemiology Unit, University of Cambridge added: ‘We need to take serious note of this study, based on a robust analysis and complementary findings from both observational and randomised trial evidence.
‘This study effectively re-endorses that the UK Government advice to consume 30g fibre per day is pretty spot on.
‘The onus is on individuals themselves, as well as public agencies, to make it happen, as average fibre intakes remain woefully low at a population level in the UK.
‘This research did not study total carbohydrate intakes specifically, but its findings do imply that, though increasingly popular in the community at large, any dietary regimes that recommend very low-carbohydrate diets should consider the opportunity cost of missing out on fibre from whole grains.
‘This research confirms that fibre and whole grain intakes are clearly important for longer term health.
She added: ‘Ultimately this research provides a solid foundation that when it comes to carbohydrates, the quality matters very much, over and above the debate on quantity.
‘Whole grain foods are typically high in fibre, and this research provides further evidence to highlight their importance and support a shift in our diets from processed and refined foods in the food supply chain towards more fibre-rich whole grain foods.’