Thank you for the answer. I was reading a little bit on the internet as well about yeast, and there are different opinions but many of them are positive but they also note that there can be some side effects, also some are saying that it is not so healthy. I really try to eat home-made food so I want from now on to make my own bread, however if I do not put yeast it may easily become hard and not easy to eat. Is there something that can change the yeast ? Thank you a lot.