Gut Health

Oats have a high content of soluble fibre in the form of β-glucan, but contain also arabinoxylans and cellulose which are mainly insoluble fibre. The fibres are not digested in the small intestine, but the soluble β -glucan is believed to increase the viscosity of the food bolus, leading to a slower gastric emptying, enhanced gut fill, and slower absorption of nutrients. β-glucans are highly susceptible to microbial attack and the intestinal flora harbouring the small intestine can modify the molecular weight and viscosity elevating properties.


In the large intestine β-glucans are readily fermented by bacteria colonizing the caecum and upper colon. Cellulose and arabinoxylans are much more slowly degraded and to a much lower extent. The degradation of the fibre components leads to increased microbial activity and the production of short-chain fatty acids and various gases. While the insoluble fibre reduces transit time and increases faecal wet weight by means of its physical presence, soluble fibre operates through an increase in microbial cells mass.


Oats have been shown to increase the proportion of butyrate, which has regulatory functions in cell proliferation and differentiation. β-glucan, however, leads mainly to the production of propionate, which is suggested as one of the mechanisms for the cholesterol lowering effects of oats and other β-glucan containing products. Recently it was concluded that β-glucans have no prebiotic potential.

 

Hughes, S.A., Shewry, P.R., Gibson, G.R., McCleary, B.V., Rastall, R.A. (2008). In vitro fermentation of oat and barley derived beta-glucans by human faecal microbiota. FEMS Microbiol. Ecol. 64, pp. 482-493.

 

Mälkki, Y., Virtanen, E. (2001). Gastrointestinal effects of oat bran and oat gum - A review. Lebensm.-Wiss.u.Technol. 34, pp. 337-347.

 

Johansen, H.N., Bach Knudsen, K.E., Wood, P.J., Fulcher,R.G. (1997). Physico-chemical properties and the degradation of oat bran polysaccharides in the gut of pigs. J. Sci. Food Agric. 73, pp. 81-92.

 

Sundberg, B., Wood, P., Lia, A., Andersson, H., Sandberg, A.S., Hallmans, G., Åman, P. (1996). Mixed-linked beta-glucan from breads of different cereals is partly degraded in the human ileostomy model. Am. J. Clin. Nutr. 64, pp. 878-885.

 

Bach Knudsen, K.E., Jensen, B.B., Hansen, I. (1993). Oat bran but not oat gum enchanced butyrate production in the large intestine of pigs. J. Nutr. 123, pp. 1235-1247.


Bach Knudsen, K. E., Jensen, B. B., Hansen, I. (1993). Digestion of polysaccharides and other major components in the small- and large intestine of pigs fed diets consisting of oat fractions rich in β-D-glucan. Br. J. Nutr. 70, pp. 537-556.

 

Bach Knudsen, K.E., Jensen, B.B., Andersen, J.O., Hansen, I. (1991). Gastrointestinal Implications in Pigs of Wheat and Oat Fractions. 2. Microbial activity in the gastrointestinal tract. Br. J. Nutr. 65, pp. 233-248.