Kosher Bread

From the statement in the Talmud that bread was not allowed in a certain Jewish court, it implies that if they wanted, they could have permitted it. We see from this that the prohibition of bread wasn't universally accepted. From here we have the support to eat now from bread made by non-jews, and we should rely on the words of the sages who states that we don't establish a decree on the community unless the majority is able to accept it... Those people who are particular with the bread of non-jews are permitted to eat on the same plates as people who aren't particular to this decree...

(1) The sages forbade eating the bread of idol worshippers because of the concern of intermarriage. Rema: and even in a situation where there is no concern of intermarriage, it is [nonetheless] forbidden. (Rashb"a §248) However, they only forbade bread made from the Five Grains (wheat, barley, oats, rye, spelt), but bread made from legumes or from rice or millet is not in the category of "regular bread" which they forbade. Rema: It is also not forbidden on account of [being] "Idolaters' Cooking," if it would not be served at kings' tables (Tur and Beit Yosef in the name of the Rosh's responsa).

(2) There are places that are lenient about this, [where] they buy bread from an idolater's bakery in a situation where there is no Jewish bakery, since this is considered a "time of pressing need." Rem"a: And some say that even in a place where "Jews' bread" can be found, it is permitted (Beit Yosef following the Mordechai; Sefer Mitzvot Hakatan; Hagaot Ashri; Mahar"i; Issur VeHeter §44). But regarding personal bread, no-one rules leniently, since the essence of the decree is because of the concern of intermarriage, and if one eats the bread of [idolatrous] home-owners, he will come to dine by them. Rem"a: However, it is not called "personal bread" unless he made it for the people of his own household, but if he made it to sell, it is called commercial bread, even if he doesn't normally [sell bread]; conversely, a baker who made [bread] for himself, it is considered "personal [bread]."

The Mordechai explains that the lenient opinion is that the prohibition of bread was not universally accepted at the beginning of the inception of the decree... (The second reason for us to allow it) is because they ruled that even though it was forbidden, the requirements of life preceded, and therefore when there isn't a Jewish baker one should be able to eat from a non-Jewish baker.

The Poskim have written that during the 10 days of repentence it is important to eat Kosher bread from a Jewish baker.

However it appears that even during the year one shouldn't take bread from a non-kosher baker where there is a Jewish baker around, unless the bread of the non-jew is nicer.