British Journal of Nutrition

Research Article

Improvement of the human intestinal flora by ingestion of the probiotic strain Lactobacillus johnsoniiLa1

Toshihiko Yamanoa1, Hisakazu Iinoa2, Mamiko Takadaa2, Stephanie Bluma3, Florence Rochata3 and Yoichi Fukushimaa1 c1

a1 Nestlé Japan Ltd, Nutrition Business Group, NYK Tennoz Building, 2-2-20, Higashi-Shinagawa, Shinagawa-ku, Tokyo, 140-0002, Japan

a2 Showa Women's University, 1–7 Taishidou, Setagayaku, Tokyo, 154-8533, Japan

a3 Nestlé Research Centre, Route du Jorat 57, Vers-Chez-Les-Blanc, 1000 Lausanne 26, Switzerland


To exert beneficial effects for the host, for example, improving the intestinal microflora, a probiotic must reach the intestine as a viable strain. These properties must be demonstrated by in vitro as well as in vivo methods. However, only a few well-designed human clinical studies have shown these properties. Lactobacillus johnsonii La1 has been shown to give many beneficial effects for the host, but it is unclear whether a viable strain of L. johnsonii La1 has the effect of improving host intestinal microflora. In the present study, a randomised double-blind placebo-controlled cross-over trial was conducted to elucidate the effect of L. johnsonii La1 on human intestinal microflora. Twenty-two young healthy Japanese women were randomly divided into two groups, and either received fermented milk with L. johnsonii La1 or a fermented milk without L. johnsonii La1 (placebo) daily for 21d. Consumption of the fermented milk: (a) increased total Bifidobacterium and Lactobacillus, and decreased lecithinase-positive Clostridium in the faeces; (b) increased the faecal lactic acid concentrations; (c) decreased the faecal pH; (d) increased the defecation frequency. These changes were stronger than those observed with the placebo. L. johnsonii La1 was identified in all subjects only after the consumption of the fermented milk. These results suggest that L. johnsonii La1 can contribute to improve intestinal microflora with probiotic properties.

(Received May 30 2004)

(Revised April 06 2005)

(Accepted April 21 2005)


c1 *Corresponding author: Dr Yoichi Fukushima, fax +81 3 5769 6290, email