There’s a common belief that 8 glasses of water or 2L a day is a good amount. But is this true in Singapore?
How much water do we need in a day?
Daily water intake can vary according to weather, body size, and activity level. Adequate hydration leads to good urine volume and better reflects hydration status than intake. Logistically, however, it is easier to measure intake than urine output. The European Association of Urology 2023 guidelines suggest 2.5 L of pH-neutral fluid daily. Similarly, the American Urological Association’s 2019 guidelines also support a fluid intake of 2.5L daily intake. The recommendations aim to ensure the body produces around 1.5L of urine to provide sufficient hydration.
How is this amount affected by higher temperatures and humidity in Singapore?
Singapore is a tropical country with year-round high humidity and temperature. As a result, we sweat a lot more than in cooler regions. Sweating is an unquantifiable fluid loss that cools down the body but, in the process, dehydrates the body. We must ensure these fluid losses are replaced beyond the usual daily requirements.
How often do you see patients with hydration-related woes? Which groups are more likely to not drink enough and why?
Dehydration is a significant cause of kidney stones and urinary tract infections (UTIs). Blood pressure, heart rate, and blood parameters are also affected by dehydration. In most cases, busy working adults are most likely to be neglecting their hydration due to their busy work during the day. Busy mothers with young children often report a lack of adequate hydration, and coupled with holding their urine, this adult group is also most susceptible to poor drinking habits. Conversely, the elderly and young are relatively well taken care of. Finally, patients with heart and kidney issues will need special care on daily recommended fluid intake.
What are your recommendations for them?
It is a simplistic notion that generalised advice like “remember to drink enough water” or “you need to drink 6-8 cups daily” is adequate as we are relatively poor at gauging fluid volume. Instead, a more practical approach would be to encourage using your favourite water bottle with a known volume and measure how many times it needs to be refilled in a day to meet the requirements.
Are there certain groups of people who need to be more careful about fluid intake, e.g. heart patients, people with diabetes or kidney issues?
Patients with heart and kidney issues are a particular group of patients that cannot drink freely using general recommendations. These patients must work with their respective cardiologists and renal physician to tailor their maximal fluid intake. Excessive fluid intake in these groups of patients can lead to unwanted fluid collection within their bodies and cause lower limb swelling or fluid in the lungs. At the same time, too little fluid predisposes them to urinary issues like urinary tract infections.
What are the recommendations here?
No fixed recommendations are available as each patient’s heart and kidney functionality levels differ. Instead, these groups of patients will need an individualised treatment plan that caters holistically to their needs and balance between too little and overconsumption of fluid.
Is water alone enough to hydrate us during hot and humid days in Singapore?
Water alone is usually adequate for regular daily hydration, but isotonic sports drinks are a popular choice to replace mineral and salt loss locally. Unless you are engaging in endurance sports, water alone should be sufficient.
Is a thirst test, or awareness of one's thirst, good enough to ensure that we take in enough water and fluids? Or are there other ways to check on our hydration level?
Thirst is a function of decreased salivation during dehydration. In the early stages, the need for hydration can be postponed due to distractions like work and young children. As a result, urine becomes increasingly yellow due to the concentration of body waste dissolved in a small volume of fluid (turns dark yellow colour). In most cases, our body can accommodate these mild states of dehydration, but kidney stone forms from the supersaturation of urine. At the same time, urinary tract infections can take hold and cause downstream issues. Naturally, these accommodation mechanisms fail during prolonged dehydration. Another tip to gauge hydration status is to look at the colour of urine. Many simple and easy-to-understand urine colour charts show the optimal urine colour.
Any recommendations for drinks to take and drinks to avoid in order to keep ourselves hydrated?
It is important to note that many commercially available drinks contain sugar or caffeine. Caffeine is a diuretic that causes fluid loss and can worsen dehydration. On the other hand, excessive intake of
sweetened beverages can prevent dehydration but worsen diabetes. Considering local habitus size, sufficient hydration with around 1.5 to 2.0L of neutral pH fluid plus additional moisture from the diet is protective against dehydration. Climate and work-related sweat loss naturally demand additional fluid intake beyond the recommended level. Finally, it is essential to hydrate regularly throughout the day and avoid excessive fluid intake in the early morning or evenings after work, as waking up at night to voids regularly affects sleep quality.
