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Effects of Resistant Starch on the Inhibition of Bone Loss and Fat Accumulation in Ovariectomized Mice.

Yu MATSUMOTO1, Yuko TOUSEN1, Rina ONO1, 2, Shin'ichi KURASAWA3, Yuya NAGAHATA4, Isao KOBAYASHI4, Yoshiko ISHIMI1＊

1Department of Food Function and Labeling, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition，
2Department of Health and Nutrition, College of Human and Environmental studies, Kanto Gakuin University，
3Department of Nutrition Management, College of Nutrition, Kanto Gakuin University，
4Product Development Laboratory, J-OIL MILLS, INC.

Resistant starch (RS) has been reported to increase mineral absorption and modulate lipid metabolism by changing the intestinal environment. The purpose of this study was to examine the efects of RS on bone loss and fat accumulation and ascertain an effective dose. The effects of RS were compared with those of soy isofavones (ISO), which are known to prevent bone loss in ovariectomized (OVX) mice. Female ddY mice aged 8 weeks underwent either sham surgery or an ovariectomy. The OVX mice were randomly divided into 5 dietary groups (n = 5-7) as follows: OVX, OVX fed 9% RS, OVX fed 12% RS, OVX fed 0.05% ISO, or OVX fed 0.1% ISO. Six weeks of supplementation with 12% RS or 0.1% ISO significantly inhibited the OVX-induced reduction in bone mineral density in the lumbar vertebrae of mice; however, this inhibition was observed to a lesser extent following supplementation with 9% RS or 0.05% ISO. OVX-induced increases in body weight, body fat mass and plasma lipid levels were inhibited by RS supplementation in a dose-dependent manner. Slight inhibition of the increase in body weight and body fat mass were seen with 0.1% ISO supplementation. Cecal content weight and β-glucosidase [EC 3.2.1.21] activity were increased in mice fed RS, and the pH of the cecal content was decreased in mice fed RS. These results suggest that 12% RS prevented OVX-induced bone loss and fat accumulation and also improved the intestinal microbiota in OVX mice.
Key words: Resistant starch, Soy isoflavones, Bone mineral density, Fat mss, Ovariectomy.

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