A study on the constituents of your favourite health beverage, and how it could reduce the odds of breast cancer
This is an abstract of a case-control study that evaluates how health beverages containing Lactobacillus casei Shirota (BLS) and soy isoflavone consumption since young could affect the incidence and occurrence of breast cancer. 662 controls aged 40 to 55 were matched for age and residential area to be included in this analysis. Diet, lifestyle and other breast cancer risk factors were also investigated using self-administered questionnaires and interviews. The study proved that the more the isoflavone consumption is, the lower the odds of breast cancer becomes. Regular consumption of BLS and isoflavones since adolescence were inversely associated with the incidence of breast cancer in Japanese women.
Beverages containing Lactobacillus casei Shirota (BLS, Yakult®, Yakult Honsha,
Co. Ltd., Tokyo, Japan) have been sold in Japan since 1935. According to the manufacturer’s data, 84% of BLS was sold through a distinctive personal home and office delivery system since 1985, and the product took up an estimated 50% or more of the Japanese fermented
dairy product market in 1970s and 1980s. This personalized delivery system helped to create a close bond between the brand and its consumers, as well as to help increase buyers’ confidence and trust in the brand’s research and products.
BREAST CANCER INCIDENCE
As compared to western countries, statistics have shown that Japan comprises a lower occurrence of breast cancer while other Asian countries proved a rapid increase, observed in the past 10 to 15 years. The number of new breast cancer cases in Japanese women surpassed that of stomach cancer to become the most frequent of all cancers in 1994. An estimated 45,700 women were newly diagnosed with breast cancer in 2003 (as estimated 36,500 with stomach cancer). One of the main reasons might be attributed to the increased estrogen exposure, one of the many important cancer risk factors, which is due to delay first delivery and decrease the number of childbirth.
In a number of epidemiology studies, the association of soy consumption and occurrence of breast cancer had been evaluated. In a cohort study by Yamamoto and colleagues, it is shown that soy consumption was inversely associated with the occurrence of breast cancer. Other scientists and professors also reached a similar conclusion while conducting these studies. The structure of soy to prevent breast cancer may be ascribed to estrogenic and antiestrogenic actions of isoflabones such as genistein and daidzein contained in soy. Intestinal flora is also known to affect the isoflavone metabolism.
Patients and test subjects were enrolled into study centers to meet case eligibility criteria. Some of them also received a questionnaire to find out their lifestyle habits, educational background, family history of breast cancer, menopause period and more.
In a nutshell, daily consumption of
BLS since adolescence had a significant inverse association with early breast cancer occurrence. A significant inverse association was also seen between consumption of soy isoflavones and breast cancer occurrence. The results are consistent with those from a case study conducted by Hirose and colleagues. BLS consumption also proved to increase Natural Killer (NK) cell activity and boosts the immune system in humans. A chemical carcinogensis study in mice showed oral intake of L. casei Shirota inhibited carcinogenesis by enhancing the NK cell activity. Increased
NK cell activity and isoflavone metabolisms are both potential underlying preventive mechanisms of the breast cancer. Soy isoflavones and their metabolites have been shown to prevent breast cancer, prostate cancer and osteoporosis in a number of other studies.
So far, no prospective study in human has evaluated how BLS consumption changes the intestinal flora and equol production. In conclusion, the population-based case-control study in Japanese women showed an inverse association between BLS consumption since adolescence and breast cancer occurrence. Soy isoflavone consumption was also inversely associated with breast cancer occurrence as shown in other related studies. Despite the study design, there is no indicated on the recommended amount of probiotic beverage and soy isoflavone for the prevention of breast cancer entirely.
Note: The article is a summarized version of the Probiotic Beverage with Soy Isoflavone Consumption for Breast Cancer Prevention: A Case-control study by the Professors at the Department of Biostatistics, School of Public Health, The University of Tokyo. It was revised on April 2013.
Yakult Senoko Factory
Culturing L. casei strain Shirota
Quality Control At Yakult Senoko
L. casei strain Shirota developed by Dr. Minoru Shirota