Fibre under the microscope

It’s not unusual to come across bold health claims for certain foods in the national media: ‘Food X causes/prevents cancer’ is a particularly popular formula for such news items. Reading these, you’re often inclined to take the news with a pinch of salt. 

So, those who came across a BBC headline on 11 January this year speaking of the “lifesaving food 90 per cent aren’t eating enough of” could be forgiven for dismissing it as just an attention-grabbing ploy by the media.

This time, however, the findings the BBC was reporting on had a bit more substance to them. The headline was prompted by a landmark study published in The Lancet and commissioned by the World Health Organization (WHO) that sifted through vast amounts of data on the effects of dietary fibre. The authors determined that this nutrient has a key role in reducing people’s risk of non-communicable conditions and lowering overall mortality rates.

The study, which was carried out by researchers from New Zealand’s University of Otago and the University of Dundee, compiled data from 185 observational studies – which in total covered 135 million ‘person years’ – and almost 60 clinical trials involving over 4,600 adult participants.

It turned out that fibre, while possibly not the most glamorous of nutrients (vitamin D seems to get all the attention these days), can naturally reduce the risk of heart attacks and strokes, as well as chronic conditions like type 2 diabetes. 

Professor John Cummings, who worked on the paper, told the BBC: “The evidence is now overwhelming and this is a game-changer that people have to start doing something about.”

John said: “This is the end of 50 years of researching dietary fibre. It is a defining moment… we now know that fibre does things in the body which give us a credible explanation for how this works.”

Falling short

The good news is that the study authors’ daily intake recommendations (25-29g fibre a day is good, over 30g is even better) are pretty much in line with the current guidance from public health bodies. Professor Nita Forouhi of Cambridge University’s MRC epidemiology unit said the study “effectively re-endorses that the UK Government advice to consume 30g fibre per day is pretty spot on.”

However, not everyone manages that much – not by a long way. Around the world, most people consume less than 20g fibre a day. On average, women consume about 17g and men 21g, and fewer than one in 10 adults in the UK manage 30g on a daily basis. 

Nita says that given the important protective role fibre plays in our diet, it’s up to all of us to address this: “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.”

Mortality stats

The researchers set data on fibre consumption against data on premature deaths from a range of conditions including coronary heart disease (CHD), type 2 diabetes, colorectal cancer and cancers associated with obesity. Comparing people with the highest fibre intake to those with the lowest, the results point to a 15-30 per cent decrease in ‘all-cause’ and cardiovascular-related mortality. 

Every additional 8g of fibre per day returned extra health benefits; increasing intake by this amount appeared to bring down incidence of CHD, type 2 diabetes and colorectal cancer – and deaths related to them – by between five and 27 per cent. Protection against stroke and breast cancer also increased. 

Daily intake of 25-29g (more or less what health bodies like Public Health England advise) was found to be “adequate”, but 30g and above was even better, with health dividends still being seen after this threshold was passed.

Overall, the researchers say that 13 lives would be saved and six cases of CHD avoided if 1,000 people went from eating less than 15g of fibre every day to consuming 25-29g.

Wonder nutrient?

While the scale of the impact is certainly eye opening, it won’t come as a complete shock to most people to hear that fibre has health benefits. Its role in maintaining a healthy digestive system and helping people feel fuller for longer is widely accepted, and fibre-rich foods tend to feature prominently in the food pyramid posters familiar to many people from their schooldays. 

Unlike other nutrients, fibre isn’t broken down in the small bowel, instead passing undigested into the large bowel, which is why it promotes a feeling of satiety after eating. Study author Jim Mann said: “Fibre-rich whole foods that require chewing and retain much of their structure in the gut increase satiety, help weight control and can favourably influence lipid and glucose levels.” 

Fibre is found in a lot of plant-based, carbohydrate-dense foods. Wholemeal bread and pasta are obvious examples, with other sources including legumes, leafy green vegetables and berries and other fruits. A single banana contains around 3g fibre, as does a serving of two Weetabix. Half a cup of rolled oats provides 9g, and two carrots 6g. 

The distinction between soluble and insoluble fibre, while once a mainstay of our thinking around nutrition, is now deemed less significant as most food that is high in fibre contains a mixture of both.

Interestingly, the findings for fibre’s protective powers could run counter to the popular ‘low-carb’ mantra that has gained ground in recent years. Nita comments: “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 wholegrains.”

Relevance to healthcare

The WHO research into fibre is relevant to almost everyone working in healthcare, simply because it touches on such a wide range of conditions – from heart disease to diabetes to certain types of cancer. Pharmacy teams are no exception, and with the Government increasingly looking to community pharmacy to help reduce the burden of preventable disease in the UK, anyone working in the sector should take note.

Specifically, pharmacy teams are to be encouraged to incorporate the new information on fibre into their conversations with patients around healthy eating. This component of teams’ role has become increasingly important as the healthy living pharmacy (HLP) initiative sees many pharmacies reach out to their local communities, for example by holding themed events focusing on an aspect of healthy lifestyles.

A good place to start for teams working in HLPs is to ensure that guidance on fibre features prominently in the store’s health promotion zone. This could draw the attention of people who don’t realise just how important this nutrient is to health and may spark some useful interactions on the topic.

For example, pharmacy teams can recommend eating more vegetables, substituting refined grains for wholegrains and snacking on nuts and seeds. Even eating plain popcorn can make a big difference, as it contains 4g of fibre for every 28g.

Remember, just as most 20-a-day smokers aren’t going to find that quitting cold turkey achieves lasting results, it may not be that case that someone with a 10g-a-day fibre intake profile doubles or triples that after speaking to the pharmacy team on a single occasion. 

However, advising them to make a succession of smaller adjustments to their daily eating habits can help them meet the target over time – potentially having a big impact on their long-term health and wellbeing.