Study Eruvin folio 29A with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
The Talmud answers: That is referring to a beet that was only partially cooked, which is dangerous.
There are some who say that Rav Hamnuna said: One may not establish an eiruv with raw beets, as Rav Ḥisda said: Raw beet kills a healthy person. The Talmud asks: Don’t we see people eating it and they do not die? The Talmud answers: There, it is referring to a beet that was only partially cooked
Rav Ḥisda said: A cooked dish of beets is beneficial for the heart, good for the eyes, and all the more so beneficial for the intestines. Abaye said: That is specifically when the dish sits on the stove and makes a tukh tukh sound, i.e., it is cooked thoroughly enough to produce a boiling sound.
Rava once said when he was in an especially good mood: Behold, I am like the intellectually sharp ben Azzai, who would regularly expound in the markets of Tiberias. I, too, am ready to answer any question posed to me. One of the rabbis said to Rava: How many apples are needed to establish an eiruv
The other Sage responded: And is it not permissible to establish an eiruv with them? Didn’t we learn in a Mishnah: All foods combine to disqualify the body of a priest who eats half of a half-loaf of ritually impure food, and to complete the measure of food required for two meals for the purpose of