A landmark study from Scotland’s St. Andrews University has shaken up conventional wisdom on hydration, revealing that water—while efficient—is not the most effective drink to keep our bodies hydrated over time. The findings, which have quickly made headlines across global media, underscore the subtle but important role that drink composition plays in fluid balance. For Thais who routinely endure the country’s sweltering heat and grapple with hydration choices ranging from iced coffees to herbal teas, the takeaway is both intriguing and practical: milk may outperform water when it comes to long-lasting hydration, though the story is more nuanced than it first appears (CNN via 10News).
Behind the headline, the study’s details matter for Thai readers who live in a climate where optimal hydration is both a daily health issue and a cultural concern. In a nation where street-side bottled water, sugary drinks, and café culture vie for attention, understanding which choices truly work best could have implications for everything from school lunch menus to the drink options provided in public offices and festivals.
The research out of St. Andrews University compared a range of beverages, from plain water (still and sparkling), to milk, sodas, fruit juices, and sports drinks. While water was absorbed quickly, drinks containing even a small amount of sugar, fat, or protein proved better at holding hydration in the body over time. The reasoning, according to the study’s lead from St. Andrews’ School of Medicine, is fairly straightforward physiology: when drinks contain nutrients like sugar, fat, and proteins, they slow the rate at which stomachs empty, causing water to be retained and absorbed more gradually.
Milk, especially, stood out. Containing sugar (lactose), fat, protein, and sodium, it holds a suite of nutrients ideally balanced to keep water in the body and slow down fluid loss through urination. Sodium’s key role as a “water sponge” means the kidneys retain more fluid, translating to less urine and steadier hydration (St. Andrews University study, 2015). It’s no wonder healthcare professionals often recommend oral rehydration solutions (which also balance sugar and salts) for people suffering from dehydration due to diarrheal illness—common in Thailand due to its climate.
Melissa Majumdar, a registered dietitian and Academy of Nutrition and Dietetics spokesperson, who commented on the research, summed it up: “Electrolytes—like sodium and potassium—contribute to better hydration, while calories in beverages result in slower gastric emptying and therefore slower release of urination.” Her take? Hydration quality varies depending on beverage composition, not just the amount.
However, there’s a caveat about sugar—a central concern given Thailand’s ranking as one of Asia’s top consumers of sweetened beverages (World Health Organization, 2023). Drinks with very high concentrations of sugar, such as sodas and fruit juices, do not hydrate as efficiently. Once in the small intestine, the body pulls water from its own tissues to dilute the sugars via osmosis. This is why high-sugar drinks may actually promote dehydration, despite feeling refreshing at the moment.
Nutrition experts stress that while sodas and energy drinks are aggressively marketed for “refreshment,” they often deliver the opposite, especially during exercise or periods of heat stress—situations Thais commonly face, from Muay Thai training to community sports to long workdays outdoors (BMJ Open, 2017).
Some of Thailand’s favorite beverages prompt specific hydration questions. For instance, is beer a valid hydration tool during social occasions? The study clarifies that alcohol acts as a diuretic, causing the body to lose more water. But lighter alcoholic drinks (with more liquid volume and lower alcohol percentage, like beer) result in less water loss than spirits. This knowledge may help shape future public health messaging around Songkran festivities and nightlife safety.
And what about Thailand’s beloved caffeine culture? Coffee, especially at moderate doses (~80 mg of caffeine or a standard cup), is just as hydrating as water, based on absorption and retention. The diuretic effects only become significant at higher intakes (over 300 mg/day, or 3–4 cups)—and even then, the impact is generally mild unless you are not used to caffeine. Adding milk to coffee, a common practice in Thailand, further supports water retention due to the nutrient mix in milk.
Voices from Thailand’s Ministry of Public Health’s Nutrition Division have recently recommended more mindful consumption of sugary drinks, especially among youth and working-age adults. The new study could reinforce discussions around updating beverage guidelines in schools, universities, and public canteens, encouraging cold, low-fat milk or even lightly salted herbal infusions as alternatives to sweetened drinks.
Thailand’s historical reliance on milk is itself a story of changing dietary patterns. In the past, cow’s milk was not a staple in most Thai diets—traditional beverages leaned heavily on coconut, soy, or local fruits. Government campaigns since the late 20th century boosted cow’s milk consumption, especially among schoolchildren, both for nutrition and for economic reasons, as part of the “School Milk Programme.” This latest research may reignite debate about the nutritional and hydration benefits of various milk products, including newer offerings based on soy or grains, particularly since some Thais are lactose-intolerant (Thailand National Food Committee, 2019).
Looking forward, Thai educators and public health officials may examine the new evidence when crafting policies—and beverage makers may seize it as a marketing opportunity. But care must be taken. As the experts caution, most people don’t need to obsess over precisely which beverage hydrates best; in eat-when-hungry, drink-when-thirsty societies, thirst naturally prompts adequate intake. Exceptions include athletes, the elderly, and those facing heat stress or illness—groups for whom careful hydration with balanced fluids (and sometimes medical-grade rehydration solutions) is critical.
For Thai readers and families, a few simple, research-backed recommendations stand out. First, plain water still stands as the most universally accessible, calorie-free, and effective daily hydrator—especially for those seeking to manage weight or diabetes risk. Second, unsweetened low-fat milk may be especially useful for children, the elderly, or people who need longer-lasting hydration—such as athletes, outdoor workers, or temple-goers on hot days. Third, sugary drinks and sodas offer little hydrational advantage and can contribute to chronic diseases when consumed excessively. And last, moderate coffee drinking (one or two cups per day, perhaps with a dash of milk) can safely count toward daily fluid intake.
As heatwaves become more frequent and intense in Thailand due to climate change, staying informed about hydration science will matter more than ever (Bangkok Post, 2024).
For today’s readers—whether you’re deciding what to pack in the school tiffin, what to order at a café, or which drink to reach for after a round of golf—remember: milk may hydrate more thoroughly than plain water, but there’s no single answer for everyone. Choose fluids that match your activity, health needs, and taste, drink regularly, and be mindful of hidden sugars and chemicals in processed beverages.
For more information, consult Thai health authorities (Ministry of Public Health) and your local medical provider. Maintain a balance, stay aware of your body’s signs of thirst, and help protect family and community health by making wise beverage choices.