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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.


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

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