Question: Is it okay to have a quick snack and drink before I daven Shacharis? Does the same apply to my wife and children?
Answer: The Gemara (Berachos 10a) writes that one mustn’t eat before davening as it is considered haughty to take care of one’s personal needs first. While most Poskim (Bais Yosef OC 89:3) hold that this prohibition is derabanan, the Minchas Chinuch (248:5) writes that it is mideoraisa and the Chayei Adam (16:1) writes that as the Gemara brings a Pasuk, it is akin to being mideorraisa. One isn’t even allowed to taste food (Shulchan Aruch OC 89:3).
The Shulchan Aruch allows one to drink water and the Mishna Berura (89:22) includes coffee and tea (if it will help his davening) though writes that one shouldn’t add sugar or milk. R’ Shlomo Zalman Auerbach (Halichos Shlomo, Tefilla 2:2) and R’ Ovadia Yosef (Yabia Omer 4:11) however, allow milk and sugar, as these are no longer considered such luxuries (See Aruch Hashulchan 89:23).
The Shulchan Aruch (OC 89:4) writes that anyone who is too weak to daven before eating may eat first. The Mishna Berura (89:24) allows one to take any medication or vitamins before davening even if it can wait till later, though in Biur Halacha (89:3), he writes that one should ideally recite the Shema first (See Aruch Hashulchan OC 89:24). Some (including minhag Lubavitch) are more lenient, and allow all to eat if it will aid their davening.
The Mishna Berura (106:5) writes that while one is obligated to train one’s children, one mustn’t prevent them from eating before davening.
There is a machlokes between Rambam and Ramban as to the extent of women‘s obligation to daven. According to Ramban’s stricter opinion (Hasagos Lesefer Hamitzvos 5), women have the same obligation as men to daven Shacharis (See Mishna Berura 106:4). Nonetheless, many rely on Rambam that writes (Hilchos Tefilla 1:2) that a short tefilla such as Birchas Hatorah suffices.
Especially on Shabbos and Yom Tov when one should not fast past chatzos (Shulchan Aruch OC 288:1), it is advisable to have a drink before davening if one will not have kiddush before chatzos.