Eco Dophilus supplies a combination of four different strains of lactobacilli & bifidobacteria Acidophilus, Kefir, Bulgaricus & Bifidum live organisms. Kefir & Bulgaricus were discovered over a century ago as being organisms responsible for traditionally preserved foods such as cheeses & fermented milks. Acidophilus & Bifidobacteria are probably the most widely researched of all the micro-organisms used in foods & food supplements. To ensure the viability of these very sensitive organisms in Eco Dophilus, they are freeze-dried & then encapsulated & packed within a triple blister film that protects them from the damaging effects of oxygen & moisture right up to the moment theyre consumed. Because of this, Eco Dophilus does not need to be refrigerated.