What is the scientific proof as to why it is not good to stand while drinking water as a Muslim?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

There are many authentic narrations of the Prophet regarding the prohibition of drinking while standing, and many other narrations about the permissibility of drinking while standing. Thus, the narrations that prohibit drinking in a standing position mean that it is disliked to do so, and the narrations about the permissibility of this act suggest that it is permissible. This is the view of Ibn Hajar and other outstanding scholars .

On the other hand, it is scientifically proven by some doctors that drinking while standing is harmful. For instance, Dr. Abdur-Razzaaq Al-Keelaani says in his book 'Al-Haqaa'iq Al-Tibbiyyah Fil-Islam, 'Drinking and eating while sitting is healthier, easier and safer as the food goes down the alimentary canal in a soft and slow way.' Whereas, drinking while standing over a period of time causes distension of the stomach and results in difficulty in digestion. The Prophet drank while standing in case of necessity as he was unable to sit down due to the large crowds while performing Hajj rituals, and he did not do this habitually.

Allaah Knows best.