A person is permitted to drink and eat while reciting chapters of Tehillim.
Sources and Explanations
It appears that this law can be learned from the law of drinking while reciting Pesukei DeZimrah (the verses of praise in the morning prayers), for it is common that a person drinks coffee or tea, recites the blessing over his drink before ‘Baruch She’amar,’ and continues drinking afterward. However, after searching, I saw that the poskim (halachic authorities) omitted the law of eating and drinking during Pesukei DeZimrah. Nevertheless, one can still learn from the law of interrupting with an action in the middle of Pesukei DeZimrah. For Rabbi Ovadia Yosef, in Yabia Omer (vol. 9, siman 10, ot 3), cited the opinion of Responsa Yagel Yaakov (Orach Chaim, siman 10) that interrupting with an action is prohibited just as speech is prohibited, and Rabbi Ovadia Yosef disagreed with him and cited a list of poskim who wrote that this does not constitute an interruption.
And even if we wish to be stringent while reciting Pesukei DeZimrah, it is clear that there is a difference between Pesukei DeZimrah and reading Tehillim. For regarding Pesukei DeZimrah, the Magen Avraham (51:3) wrote that one must be careful not to interrupt with speech because of the blessings that one says at the beginning (Baruch She’amar) and at the end (Yishtabach), and so wrote the Igrot Moshe (vol. 1, siman 22). There is also another concern, based on what the Mishnah Berurah cited (54:5, in the name of the Eliyah Rabbah in the name of the Mateh Moshe), that the kelipot (forces of impurity) prevent the prayer from ascending, and through Pesukei DeZimrah one cuts them off, and when one converses, those troops that, due to our many sins, wage war among us return to it because of this transgression; therefore it is proper not to converse. End of his words. And regarding reading Tehillim, the Be’ur Halachah (422:4, s.v. Aval) already wrote that a person may interrupt for anything (and see what we wrote on this in the law of interrupting with speech, that although according to halacha it is permitted to interrupt, the interruption nevertheless detracts from the quality of the reading, as the Ben Ish Chai explained there, that the reading ascends mixed with idle words). Therefore, reading Tehillim is more lenient, as eating and drinking do not spoil the quality of the reading.
From the sefer “Shaf Veyativ – Laws of Saying Tehillim” by Rabbi Shay Tahan, Chapter 7: What Is Forbidden and Permitted When Saying Tehillim, Halacha 5 (p. 123 in the print edition). Translated from the Hebrew original.
