I showed my surprise to a serious young man who was drinking coffee during Shacharit. He said it helps him daven and is permitted. Can that be correct? Answer:
We are not discussing one with special physical/medical needs.
It is forbidden to eat before davening Shacharit (Berachot 10b), as derived (although it is probably Rabbinic) from "Do not eat on the blood" (Vayikra 19:26) – i.e., before you have prayed for your blood (=life). It is considered haughty to indulge in food before addressing Hashem, and therefore drinking water, which is not indulging, is permitted (Shulchan Aruch, Orach Chayim 89:3). Many Acharonim permit drinking coffee and tea, specifically when one needs it to concentrate on davening; adding flavor enhancers is questionable (see Mishna Berura 89:22).
397 - Parashat Zachor with Different Pronunciations
398 - Drinking during Davening
Tefilla is supposed to be done with reverence and awe. Many halachot govern how one’s body, clothes, and surroundings must be at that time (see Shulchan Aruch, OC simanim 97-99). The height of tefilla is considered "standing before the shechina" (Rambam, Tefilla 4:16). Eating and drinking when in close contact with Hashem is considered a big chutzpa (see Shemot 24:11). Since this is antithetical to tefilla and a beit knesset is set aside for tefilla, it is forbidden to eat there (Shulchan Aruch, OC 151:1). The incongruity between eating and davening is behind the halacha of not eating even before davening. It seems obvious that eating in the midst of davening is worse than eating before. Therefore, even if one davens in a place where he may eat, e.g., at home, in a beit midrash (Rama ad loc.) or he follows the lenient minhag (see Be’ur Halacha ad loc.), he should not drink during davening.
One can deflect these conclusions. If drinking coffee is permitted before davening, then it is not halachic eating, and who says the halacha is stricter during davening than before? (The counter-argument is that it is only permitted before due to need, and if one can drink before davening, why let him drink during it?) Also, assuming it is forbidden during Shemoneh Esrei, who says P’sukei D’zimra’s lesser level of "meeting Hashem," as a preparatory/introductory stage, carries the same weight (Rama, OC 89:3 may equate them)? Indeed, many of the halachot of tefilla refer only to Shemoneh Esrei (see Mishna Berura 97:3).
What do the sources say? There are many sources on drinking before davening; I did not find classical sources on this question. Why would there not be much discussion of the matter? It is either because: A) It is obvious that it shares the same halacha as eating before davening; B) It is obviously permitted; C) It is obviously forbidden; or D) Few people were interested in doing such a thing, for sociological or convenience reasons. Intuitively, I find A and B implausible. C seems logical (Chevel Nachalato 17:3 cites Rav Y. Ariel as saying it is forbidden). D is a possibility. It is very possible to combine C and D. Perhaps there is not a full-fledged issur, but sensitivity to shul and tefilla made it taboo. I spoke to many (Ashkenazi) decades-long shul attenders, none of whom can recall until recently healthy people drinking during P’sukei D’zimra and later. Those who need coffee, drink before davening. Then they enter shul, put on tefillin, and DAVEN ONLY. That is a very appropriate minhag even IF arguably not fully required. There are signs that some in the new generation view things differently. While they can be wonderful Jews and daveners, they would be pulling things in the wrong direction, according to several rabbanim (and non-rabbanim) I have discussed the topic with. Drinking while davening degrades the atmosphere of the shul in our eyes.
In some Sephardic communities, it has been more common for at least decades to continue, during P’sukei D’zimra, drinking coffee begun earlier. The Yalkut Yosef (OC 51:3), while preferring to avoid on the grounds of possible hefsek (even if the beracha was done before), does not mention fundamental grounds. I pray that the Ashkenazi minhag of full opposition will survive.