Volume 90, Issue 1, July (2003), pp. 119-125 © The Author 2003
doi:10.1079/BJN2003883

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Plasma enterolactone or intestinal Bifidobacterium levels do not explain adenoma formation in multiple intestinal neoplasia (Min) mice fed with two different types of rye-bran fractions

S. Oikarinen¹, S. Heinonen², S. Karppinen³, J. Mättö³, H. Adlercreutz², K. Poutanen³, M. Mutanen^1
1Department of Applied Chemistry and Microbiology, Division of Nutrition, PO Box 27, FIN-00014 University of Helsinki, Finland
²Institute for Preventive Medicine, Nutrition and Cancer, Folkhälsan Research Centre and Division of Clinical Chemistry, FIN-00014 University of Helsinki, Finland
³VTT Biotechnology, PO Box 1500, FIN-02044 VTT, Finland

 (Received 11 July 2002–Revised 14 January 2003–Accepted 3 March 2003)

The study was designed to evaluate whether two types of rye-bran fractions result in distinct bifidogenic effect or enterolactone production in multiple intestinal neoplasia (Min) mice and whether these parameters are associated with intestinal tumorigenesis in this animal model. The experimental diets were a non-fibre diet (control), a rye-bran diet, and diets containing either the soluble extract or the insoluble fraction prepared from rye bran. The main result on adenoma formation in these experiments was the observation that the soluble extract increased number (P=0·012) and size (P=0·008) of adenomas in the distal small intestine when compared with the non-fibre group. All rye-supplemented diets supported similarly the in vivo growth of Bifidobacterium (10⁸–10⁹ colony forming units/g) in Min mice, whereas the non-fibre diet lowered intestinal Bifidobacterium below the level of detection. The results show that water solubility does not affect the bifidogenicity of rye bran. Mean plasma enterolactone concentration was highest in the rye-bran group (30·0 nmol/l; P=0·002), which along with the soluble-extract group (16·2 nmol/l; P=0·024) differed significantly from the non-fibre diet group (7·5 nmol/l). Thus, the mice fed with the rye bran were the best enterolactone producers. In conclusion, rye bran and rye fractions influence adenoma formation in Min mice to a varying degree but plasma enterolactone levels or the production of bifidogenic bacteria do not mediate the effect.

Keywords:
Min mice, Rye bran, Bifidobacterium, Lignans, Enterolactone

Abbreviations:
cfu, colony forming units, Min, multiple intestinal neoplasia