The dietary fibre content of cereals in the Nordic countries is higher than estimated
According to a recently completed study by the Finnish Food Safety Authority Evira, the dietary fibre content of oats, rye and wheat is higher than previously estimated. In 2013 and 2014, Evira studied the dietary fibre content of cereal samples collected from Norway, Finland, Sweden and Estonia. Almost all of the new results were greater than those previously reported by Fineli, the National Food Composition Database in Finland. On the basis of the analyses, oat flakes and rye flour obtained from the sampled countries contain an equal amount of similar dietary fibres. By contrast, in whole-grain flour statistically significant differences in the amount of dietary fibre were detected between the countries. For the first time, the concentrations of dietary fibre in industrial raw materials were also studied.
Dietary fibres were analysed by Evira using a method introduced in 2014 and validated in 2016 by Finas, the national accreditation body in Finland. This method can be used to determine the content of long and short fibres, both soluble and insoluble in water.
Dietary fibres contribute positively to health
Dietary fibres contribute positively to health, and the diet of the Finns should contain more of them than is currently the case. The recommended intake for women is 25 g per day, and for men 35 g.
Fibres insoluble in water improve gastric functioning, while water-soluble fibres lower blood serum cholesterol levels and slow down the rise of blood glucose levels. Many fibres are broken down slowly in the colon, thereby protecting against cancer of the large intestine. Short dietary fibres in particular, known as oligosaccharides, contribute to the growth of beneficial lactic acid bacteria in the colon.
Wheat and rye bran are excellent sources of dietary fibre that is insoluble in water. 100g of wheat bran contains nearly 50 g of fibres, and 100 g of rye bran more than 30 g. Of the examined cereal samples, oat bran contains the largest amount of water-soluble dietary fibre 100 g of oat bran contain 6 g.
"The oat bran dietary fibres mostly comprise beta-glucan, a commonly known substance, which, among other things, reduces LDL values in blood or cholesterol that is referred to as bad cholesterol. Rye is also rich in water-soluble fibres, which mostly consist of arabinoxylan. It is also found in wheat, the arabinoxylan content of which helps, according to a generally accepted belief, to curb the rise in blood sugar level after meals. Beta-glucan also has a similar effect", comments Helena Pastell, Senior Researcher and Doctor of Food Science at Evira.
Of the examined cereals, oat bran exhibited the lowest content of oligosaccharides. The highest content of oligosaccharides is found in rye bran, in which they may amount to close to 6 g per 100 g of bran.
Wheat flour, normally used in households for baking pastries, contains around 4 to 5 g of fibre per 100 g, in contrast to, for example, wholemeal wheat flour, which contains more than twice that amount of fibre.
The National Food Composition Database needs to be updated
The results were compared as part of a collaborative effort conducted within the scope of the Nordic Food Analysis Network, in which, of the Finnish operators, not only Evira but also the National Institute for Health and Welfare (THL) are involved. The samples were obtained in each country from retail shops based on their market share and the availability of products at shops measured in terms of shelf metre.
"Laboratory analyses of dietary fibres are laborious and time-consuming, which is why there is no point in analysing all food products separately in each country. Results of research conducted in Finland on rye flour and oat flakes can well be lent to the composition databases of the other Nordic countries. By contrast, the amount of dietary fibres in wholemeal wheat flour exhibited statistically significant differences between the countries, something that must be taken into consideration. Variation was most extensive in dietary fibres that are insoluble in water", Pastell says.
The results of this study on cereals dietary fibres were published in the following peer-reviewed scientific publication
Rainakari, A., Rita, H., Putkonen, T., Pastell, H.
New dietary fibre content results for cereals in the Nordic countries using AOAC 2011.25 method.
Journal of Food Composition and Analysis 2016: 51, pp. 1. - 8.
The article also presents the dietary fibre content of almost twenty Finnish cereal products as well as information on consumer products and raw materials used by the industry.
The dietary fibre analyses were largely funded by the Ministry of Agriculture and Forestry and the Finnish Food Research Foundation.
For additional information, contact:
Helena Pastell, Senior Researcher, Doctor of Food Science, Chemistry Laboratory Services,
tel. +358 (0)50 375 0968