OptiBac Probiotics ‘Bifidobacteria & fibre’ is especially for those seeking a natural option. It contains Bifidobacterium lactis BB-12, thought to be the most researched strain of the entire Bifidobacterium family, as well as 4g of FOS (Fructooligosaccharides) for natural fibre. This supplement is safe and gentle, and highly researched in thousands of people including pregnant women and older generations, and is proven to survive to reach the gut alive.