A bulky issue
The health benefits of dietary fibre are well established and the need to include sufficient fibre in the diet is an important aspect of dietary recommendations around the world. So there should be no excuses for not knowing what dietary fibre is and how to eat enough of it as part of a normal, balanced, healthy diet. Well, not really.
The benefits of including the fibrous parts of plants - or non-digestible 'roughage' - in the diet, mainly in terms of improved bowel transit, have been known for centuries. Indeed, in earlier times they could hardly be avoided, such was the primitive nature of food technology, when all bread, for example, was necessarily wholegrain. But food technology has come a long way over the past 100 years or so, providing us all with far more choice and, simultaneously, more enjoyable food along the way.
A direct consequence of this trend - and the parallel progress made in nutrition science - has been the recognition of an associated rising risk of eating insufficient fibre for good health. And then, over the past 20 years or so, thanks to the efforts of diligent food scientists, a number of less obvious categories of dietary fibre have come along to confuse us. These include terms such as 'soluble' (ie. non-fibrous, water-soluble) fibre and 'functional' fibre, which are usually soluble but generally processed in some way and isolated from their natural-origin food source.
As the British Nutrition Foundation's Dr Joanne Lunn says: "Dietary fibre is not an entity, but a collective term for a complex mixture of substances with different chemical and physical properties, which exert different physiological effects."
What is fibre?
There is general agreement that, to qualify as dietary fibre, a substance must be non-digestible in the stomach and small intestine; but in Europe, at least, there is still debate about the various categories and their eligibility, and the analytical methods used to identify and quantify them.
As Lunn points out, these various non-digestible components are not interchangeable and it is important that dietary fibre comes from a range of sources to ensure maximum health benefits. Traditional 'insoluble' fibre adds bulk and retains water, easing bowel transit, while types that are slowly fermentable in the large intestine - such as the so-called resistant starches and some prebiotics - bring other improvements to gut function, and rapidly fermentable, viscous fibres are identified with cholesterol-lowering effects.
Lunn says there are five main areas where there is sufficient evidence that can be assessed to provide a consensus opinion of the health effects of dietary fibres:
?improvements in gastro-intestinal health
?improvements in glucose tolerance and insulin response
?reduction of hyperlipidaemia, hypertension and other chronic heart disease risk factors
?reduction in the risk of some cancers
?increased satiety/weight management.
According to Lunn, the lack of clarity at international level over the definition and measurement of fibre in the diet is hampering progress towards recommendations that are fully accepted, and thereby progress towards nutrition and health claims. It is a chicken-and-egg issue - you can't make recommendations until definitions have been agreed.
Dr Chris Seal of Newcastle University's human nutrition research centre says: "Problems and issues around analytical definitions are still ongoing in the EU. It's hugely important for harmonised nutrition claims and even for labelling products as 'high fibre' or not, never mind the health claim requirements."
Dr Sandra Einerhand, director of health and nutrition, Europe, Tate & Lyle, adds: "Harmonisation at the EU level would definitely be beneficial. Until then we have to comply with national rules for 27 different countries." In this regard, the European Food Safety Authority published a statement on dietary fibre in July last year, which is to be considered by an EU Commission panel in November.
The statement proposed that dietary fibre should be defined as all carbohydrate components that are non-digestible in the small intestine, plus naturally associated minor components, especially lignin.
At EU level, however, discussions are still ongoing and, according to Einerhand, probably delayed following submission of late information at a recent Codex meeting.
At any rate, in the drive to increase human intake of dietary fibre there is surely commercial potential for food ingredients companies, since functional ingredients that qualify as dietary fibre will certainly have a part to play. Both Tate & Lyle and Beneo Group see health claims as an important part of their marketing efforts. "We've done a lot of clinical research to substantiate health claims and still aim to do more," says Einerhand, "because, unfortunately, the EU regulations are not entirely clear at the moment in respect of what level of evidence is required."
Tim van der Schraelen, marketing manager at Beneo Group, points to the "spectacular" growth in products with health claims since 2001. "Within this market, it is clear that gut health claims are becoming more and more important. In 2003 these claims were almost non-existent, but since then the gut health market has grown considerably, with fibre claims being a major part of it."
the technical challenge
Are there still technical challenges in adding fibre ingredients to a wide range of foods? According to Tate & Lyle, which currently has three fibre products - polydextrose, a soluble gluco fibre and resistant starch, all derived from maize - it is important to have a range of products, from low to high molecular weight, to maximise the opportunity. "Our company aims to develop a range under the Promitor brand," says Einerhand. "For a range of foods - from beverages, dairy, sauces and dressings to bakery - you need a range of products for compatibility. And then they don't all provide the same health benefits, while taste issues can still be a challenge."
Van der Shraelen, however, sees few technical obstacles. "The Beneo-Orafti portfolio contains a wide range of different inulin and oligofructose types with different technical properties which address, for example, solubility, particle size distribution, dispersibility, process and storage stability," he says. "Crucial in the development process is choosing the right ingredient for each food application. This is determined by the nutritional target (eg. prebiotic, fibre, improved digestion, better calcium absorption), the technical target (eg. sugar or fat reduction) or the processing and storage conditions."
Meanwhile, at Alfred L Wolff, which supplies a water-soluble acacia fibre under the Quick Fibre brand, marketing manager Anita Benech says the low viscosity, thermo-stable, acid-stable product, which is also a natural emulsifier, is easy to process in liquid and solid recipes, and can be incorporated without any pre-treatment. "It has a fully neutral taste and flavour, and is now defined as an ingredient in Europe," she adds. "It can be integrated into the most diversified recipes - such as cereals, cereal and fruit bars, snacks, bakery or dairy products and beverages - in all products targeting fibre fortification or enrichment."
But is 'with added fibre' a selling point? Both Beneo and Tate & Lyle say "yes", pointing to consumer research indicating that most consumers do know fibre is good for health, but they don't eat enough of it.
Dorothy Mackenzie at brand agency Dragon Brands is more cautious, however. "The HealthFocus survey shows fibre is one of the things people are trying to increase their consumption of," she says. "However, it is less clear that they are trying to eat foods that have 'added fibre'. It is probably more likely they are keen to eat foods that are naturally rich in fibre - so oats and wholegrain products are increasing rapidly.
"Fibre still has a bit of an image problem, though, with the word itself being a bit of a turn-off. My impression is that there is still a low level of understanding of the difference between soluble and insoluble fibre. On the whole, fibre is interpreted as bulky fibrous material, so soluble fibre needs quite a lot of explanation. Perhaps it's better to focus on the benefits of the fibre, rather than the fibre itself."
