Physiology

The other day a friend told me about a peculiarity she observed during a recent trip to China: the glass of ice water on the table is almost a rarity. Instead you’ll find a pot of green tea, a bowl of broth, or just nothing cold. For centuries, in much of Asia, drinking cold liquid during a meal has been an eccentricity more typical of the West than there. What for a long time seemed like a quaint custom, or directly a matter of infrastructure—ice was not always available everywhere—turns out to have a pretty solid physiological explanation. The temperature of the water we drink while we eat is not a minor detail. It affects the movements of the stomach, the rate at which it empties, and how the muscles of the digestive system behave. And science, although with important nuances, is beginning to agree with what millions of people in Asia have been practicing for millennia. Before getting into the physiology, we must understand how this debate has reached the West. It has not been through a medical congress or a scientific journal. It has arrived, like so many other things, through TikTok. The phenomenon is known as chinamaxxing either Becoming Chinese: a viral trend in which thousands of Western people adopt lifestyle habits from Chinese culture, including drinking hot water. According to documents The New York Timeshot water has become “the new superstar of online well-being”, with influencers documenting how this habit deflates them, gives them energy and improves their digestion. But what the Internet presents as a revolutionary discovery is nothing new. This practice has been rooted for thousands of years. in Indian Ayurveda—where the morning ritual of drinking hot water is known as usha paana— and in Traditional Chinese Medicine, where cold is believed to “turn off the agni“, the digestive fire, and weakens the vital energy or Qiforcing the body to expend extra energy to warm the stomach. Hot water, on the other hand, balances the Yin and the Yang and keeps the body calm. Just because something is part of an ancient tradition does not automatically make it scientific truth, of course. But it doesn’t disqualify him either. The question is what exactly science says when it begins to analyze what happens in the stomach according to the temperature of what we drink. What really happens in the stomach? To understand the debate, we must separate two things that are often confused: the effect of drinking water during a meal and the effect of the temperature of that water. They are different questions with different answers. On the one hand, regarding water itself, there is a widespread belief that drinking water during meals dilutes gastric juices and digestive enzymes, slowing down digestion. Medical portals such as HealthLine They explain that there is no solid scientific evidence that water dilutes gastric juices or significantly hinders digestion. The stomach has a dynamic regulatory system that detects changes in pH and automatically secretes more hydrochloric acid to compensate. Drinking a glass of water during a meal hardly alters that balance. Marina Domene, head of nutrition at SHA Spain nuances in Vogue Where is the real limit: the problem is not drinking water, but excesses. “What is not recommended is drinking excessive amounts, more than two or three large glasses, as it could distend the stomach too much and temporarily dilute the enzymes,” he explains. It also points out that there are specific contexts where it is advisable to be more careful: in people who suffer from hypochlorhydria – low production of stomach acid – it is not recommended to consume liquids during meals. On the other hand, regarding temperature the panorama changes and this is where physiology begins to agree with Asia. The temperature of the liquids directly affects gastric motility, that is, the muscle movements of the stomach that drive digestion. Domene explains it clearly: “Cold drinks can slightly slow down gastric emptying and constrict the blood vessels of the stomach, which in sensitive people can be heavy. Hot liquids, such as broths or infusions, have a relaxing effect on the smooth muscles of the stomach.” This is not just a clinical opinion. There are studies that support this, such as research on the effect of temperature on gastric emptying have observed that very cold drinks, around 2-5 °C, can temporarily slow down the initial phase of gastric emptying compared to liquids at body temperature. Drinks at 4°C also disrupt antral and pyloric contractions, briefly retaining stomach contents. An experiment with 11 young men who consumed 500 ml of water at different temperatures found that water at 2 °C reduced the frequency of gastric contractions compared to water at 60 °C, and that lower muscle activity was related to lower subsequent caloric intake. The sample sizes of these studies are modest—it should be said—but their results consistently point in the same direction. A study published in Gastroenterology Nursingfocused on patients who had recently undergone colon surgery, observed that the consumption of hot water had a positive impact on subsequent bowel movements. It is not a study designed for healthy people, but it adds evidence about the role of temperature in intestinal motility. Gastroenterologist Dr. Lisa Ganjhu, consulted by The New York Timesdescribes it more graphically: during the night, the digestive system slows down. Hot water generates waves of contraction and relaxation in the muscles of the esophagus, stomach and intestines. “It’s basically telling everyone, ‘Okay, get up. We’ve got to get going,’” he explains. Why did they take that path and not another? The physiological explanation that science offers today connects quite well with what traditional Chinese medicine and Ayurveda have been saying for centuries, although in completely different languages. In China, Japan and much of Southeast Asia, It is common to accompany meals with hot tea or soup. It is not a fad or a recent trend: it is part of the structure of food. The broth does not close the menu, it accompanies … Read more