Surprise! Drinking Water Wrongly Can Damage Your Kidneys

TRANSCRIPT

Did you know that drinking water wrongly can potentially harm your kidneys? By “wrongly,” we mean you can either drink too much or too little water. Both can potentially harm your kidneys.

Now you may wonder, what’s the right amount of water to drink? Many people believe in the old adage that you should drink 8 cups, or about 2 liters, of water daily to stay hydrated (1). This is actually a myth because people tend to confuse “water intake” with “fluid intake.” Water intake is simply drinking water, but fluid intake includes all drinks and foods containing water. When we talk about keeping yourself hydrated, it’s about everything you consume, not just plain water (2). That’s why the advice to “drink 2 liters of water daily” is not exactly correct for everyone.

In this video, we will give you tips on monitoring your water intake for the best kidney health: from when to drink water, to how much to drink, and the safety levels of different types of water. Note that in some cases, drinking only plain water may not be enough.

Next, we will explain in detail how drinking too much or too little water can damage your kidneys.

Before we dive in, please note, all the information in this video is created by real people, thoroughly fact-checked, unbiased, and reviewed by qualified professionals.

Drinking Too Much Water

While experts are still determining the proper amount of water needed daily, drinking more than 1 liter or about 1 quart every hour will cause extra stress on the kidneys (1, 3). According to the Merck Manual, one estimate suggests that repeatedly drinking more than 23 liters or 24 quarts of water over 24 hours may cause excessively high water levels in a young adult with normal body function (4).

Rest assured: your kidneys usually filter out excess water. So, water toxicity, overhydration, water intoxication, or drinking too much water occurs rarely in healthy people. People at risk for overhydration are endurance athletes, premature babies, and people with certain mental illnesses and pituitary disorders (1, 4). Water intoxication may also occur in those with kidney, liver, and heart disease due to their impaired abilities to maintain proper fluid balance (5). People taking on drinking challenges, and those who have consumed large amounts of alcohol may also be subject to water toxicity (6). Certain medications, such as diuretics, antidepressants, antipsychotics, and drugs such as MDMA or ecstasy, may cause people to consume excessive amounts of water as well (1, 4).

Drinking too much water too quickly dilutes the sodium level in the blood (7). Healthy sodium levels are between 135 and 145 mEq/L. When sodium levels are under 135 mEq/L, this is known as hyponatremia (7). Healthy kidneys can remove excess water at a rate of about 1 liter or 1 quart per hour (8).

Water intoxication occurs when the kidneys can’t remove water fast enough to maintain the normal sodium balance (7). Water will then move into the cells, which contain more sodium, causing fluid retention (6). The fluid retained in cells causes them to swell or become too big. This state, a main concern of water intoxication, may even cause swelling in brain cells, known as cerebral edema. Symptoms of water intoxication may include trouble thinking clearly, nausea, and vomiting. Early treatment is essential, as severe cases may cause seizures or death (6).

During the 2002 Boston Marathon, almost 500 runners enrolled in a study investigating race-related causes of hyponatremia (9). After finishing the race, over 60 marathoners experienced low blood sodium levels related to overhydration. To reduce the risks of hyponatremia, the researchers recommended that long-distance runners estimate their water needs during a marathon. They should weigh themselves before and after training runs and hydrate according to how much fluid they’ve lost through sweating and how thirsty they feel (9).

Another study, published online in 2021 with BMJ Open, surveyed 590 patient reports (10). The study included patients with hyponatremia resulting from water toxicity. On average, the patients drank 8 liters of fluids daily. Severe effects included seizures and coma, while other symptoms reported were vomiting, lightheadedness, and weakness. Unfortunately, a small number of patients experienced brain damage due to complications, while over 75 of the patients died (10).

Overall, drinking too much water, although not common, may cause low sodium levels in the blood and fluid retention. These problems can cause severe damage to the kidneys. Studies also highlight the dangers associated with overhydration that may lead to death. Next, learn how kidney damage can also occur from drinking too little water.

Drinking Too Little Water

To stay hydrated, you should know when you need more water. Under normal circumstances, water loss occurs when we sweat, breathe, defecate, and urinate. For instance, during physical exercise, you breathe faster and sweat more. Pregnant or nursing women have additional water requirements. Also, water needs may increase if you’re in hot weather or high altitudes (2). When you are ill, you may lose significant amounts of water with a fever, vomiting, or diarrhea.

Dehydration occurs when water is lost faster than it can be replaced. Due to the abundance of water in most places, people can easily avoid becoming dehydrated. However, many adults, particularly older adults, are chronically dehydrated. Some older individuals have weakness, decreased thirst sensation, diabetes, or kidney damage that may put them at risk (11). The risk of dehydration also increases if you drink too much water without enough electrolytes. Still, we’ll discuss this later.

When the body is dehydrated, it attempts to correct the fluid imbalance through several mechanisms (11). Special sensors in the brain, known as osmoreceptors, detect changes in the blood’s fluid and electrolyte balance. The hypothalamus signals the pituitary gland to release antidiuretic hormone (ADH). ADH tells the kidneys to stop releasing fluid into the urine and instead reabsorb it into the blood.

The kidneys also have a mechanism to compensate for dehydration. When the blood pressure drops, they release the hormone renin, which activates another system that increases blood pressure. Renin turns another hormone, angiotensin I, into angiotensin II. Angiotensin II signals the adrenal glands on the top of the kidneys to release aldosterone. Then, aldosterone signals the kidneys to reabsorb more sodium and water. This brings the blood pressure back into balance while also helping you become hydrated.

Dehydration should be addressed to avoid long-term kidney damage, even in mild cases (12). If dehydration continues and becomes severe, the kidneys will develop acute kidney injury (AKI), which can occur in as little as two days (13). Low fluid volume also increases the risk of urinary tract infections and kidney stones (14). Even waste products may build up in the filtration system or return to the blood unfiltered (14).

Fortunately, the hypothalamus also signals when you need to drink water. In response to low blood volume, the brain triggers thirst and, interestingly, detects when you swallow fluids (15). However, by the time you become thirsty, you may already be mildly dehydrated. So, it’s best to sip water throughout the day and drink more when you are thirsty (16). Older adults or those with brain injuries may have a reduced ability to sense thirst and should make sure to maintain adequate fluid intake (17, 18).

A large 2021 study published in Clinical and Experimental Nephrology examined the water consumption of over 50,000 Koreans (19). The results showed that increasing water intake was important for preventing kidney damage, especially in older men. As the participants drank more water in proportion to their body weight, their kidney function improved (19).

In another 2016 study published in the American Journal of Physiology, researchers highlighted dehydration as a serious concern among field workers. This population has increased rates of chronic kidney disease. The study’s findings suggested that thousands of field workers’ deaths may be related to chronic dehydration. Researchers looked at various types of fluid intake in dehydrated rats to determine the effects on kidney damage prevention. They concluded that the rats who drank soda had the lowest hydration and the worst kidney damage. Rats drinking water or water sweetened with a natural sugar substitute only suffered mild effects of dehydration (20). So, it’s important to stay hydrated by drinking water—not soda.

This section discussed water loss and dehydration. Kidney injury, kidney stones, and urinary tract infections may result from inadequate fluid intake. Next, we’ll highlight ways to monitor your personal needs for fluid balance.

Monitor Your Water Intake for Kidney Health

As mentioned, it’s essential to pay attention to your thirst. Urine color, odor, and frequency may indicate how well fluid is balanced. Clear urine usually suggests that you are hydrated enough or too hydrated. When you drink more, you urinate more frequently (18, 21).

When you are dehydrated, your urine turns yellow or amber and may have a strong smell. As the urine becomes more concentrated, you’ll also make fewer trips to the bathroom. In this case, you should increase your water intake. However, other factors, such as infections and kidney disease, may also cause changes in urine characteristics (21).

When you are not hydrated, you may wonder if you should have an electrolyte drink. The answer is yes and no. First, let’s discuss what electrolytes are, why they are important for healthy body functioning, and situations when the body may experience electrolyte imbalance.

Electrolytes are tiny particles that carry an electrical charge (12). They help the body perform vital functions, including nutrient and waste transport, fluid balance, muscle contraction, and nerve conduction. They also help maintain your acid-base balance, heart rate, and heart rhythm. You’ve probably already heard the names of the most common electrolytes: sodium, potassium, chloride, calcium, magnesium, phosphate, and bicarbonate. Like water, they leave the body naturally through urine, feces, and sweat (12).

You may lose more electrolytes along with fluid during illness with fevers, vomiting, or diarrhea (12). Electrolytes can also be lost when you are sweating heavily due to exercise or hot and humid outdoor temperatures and also when you are taking certain medications (12). High blood sugar in people with diabetes also causes both electrolyte and fluid loss (14).

Now, when you become dehydrated in these situations, electrolyte replacement drinks are helpful for replenishing fluid and electrolytes quickly. Some people may want to drink them after mild or moderate exercise, but water will usually be sufficient. However, these drinks may still be beneficial after exercising for over an hour with intense sweating or under an hour with vigorous exercise in high temperatures (22).

Electrolyte drinks aren’t generally needed throughout the day and may be harmful in some instances. They contain high amounts of sodium, potassium, magnesium, and chloride (22, 23). For people with kidney or heart conditions, these drinks may increase blood pressure or dangerously raise blood electrolyte levels (22). Some electrolyte drinks have high amounts of sugar, which can contribute to diabetes, obesity, and other health problems (24). They may also be full of unhealthy food dyes, preservatives, and artificial sugar substitutes. So, it’s best to drink water. If you must drink these electrolyte drinks, read the ingredients label carefully (25).

Most foods also contain electrolytes, but whole food sources from plants are the most nutritious. Good choices would be fruits, such as citrus and coconut water, but also some leafy green vegetables, honey, ginger, brine from fermented foods, beans, seaweed, pumpkin seeds, and fatty fish. These are all excellent examples of nutrient-dense electrolyte food sources (25, 26).

If you’ve watched the entire video so far, you will be able to recognize common myths about staying hydrated.

Myth #1: You must drink eight glasses of water daily.

Myth #2: The more water you drink, the better it is for your body.

Myth #3: Drinking water is the only way to stay hydrated.

Myth #4: You should always drink high amounts of electrolytes or sports drinks when exercising (18).

Another myth is that caffeine and alcohol are dehydrating. While both are diuretics that increase urination frequency and volume, moderate consumption can still help maintain your hydration (27). However, limit caffeine and alcohol along with other sweet drinks since they can have damaging effects on the kidneys when consumed excessively (24). Up to 400 mg of caffeine a day, or about 4 9-ounce cups of coffee, is considered safe (28).

Some people with kidney disease need to be cautious about the amount of water they drink. As kidney damage worsens, doctors may prescribe a limited fluid intake (29), particularly for those on kidney dialysis. At this stage, the kidneys’ capacity to create urine and regulate the amount of fluid in the body is greatly reduced. Some people may even stop making urine (30).

However, people with kidney stones or urinary tract infections (UTIs) should increase their hydration. Flushing the kidneys with water will help the stones fall apart. Besides that, drinking water will also help fight UTIs. This is because flushing the kidneys and bladder helps remove unwanted bacteria (29).

You may be wondering if bottled water is better than tap water and what type of water you should drink for kidney health. There are a few factors to keep in mind. Tap water standards around the world vary in their safety (31). Tap water’s purity depends on the location where you get your water. Not all drinking water at public facilities is safe (31). Some tap water may have high levels of manufactured chemicals or even natural minerals that are linked with health conditions such as cancer (32).

In places where water sanitation is poor, people drink more bottled water. However, in places where tap water quality meets safety standards, marketing efforts may create the belief that bottled water is a better alternative. However, bottled water quality can also vary greatly, depending on its source, the material of the bottle, how the water is stored, and the substances in the water itself (31). In the United States, bottled water safety standards are similar to those of tap water, but this may not be true worldwide (33). No matter which type of water you decide to drink, drinking from a safe source is highly important (34).

Sugary beverages may seem like a good choice when you are thirsty. However, they aren’t hydrating and might even cause more harm than good (20). Drinks containing high amounts of sugar include sodas, smoothies, coffee, energy, and fruit drinks (24). Not only do they cause an unhealthy increase in blood sugar levels, but they can also increase dehydration (20).

Beverages high in sugar trigger ADH release, which causes the kidneys to retain fluid and concentrate the urine. This puts extra stress on the kidneys to filter blood. Also, sugar from sweetened drinks can increase the production of uric acid and other byproducts. These waste products can cause inflammation and the creation of harmful substances called free radicals. Free radicals may cause damage within the tiny filtration structures of the kidneys (20).

Sodas are also linked with causing kidney stones (35). Drinking large amounts of caffeine in coffee, tea, and energy drinks can cause high blood pressure, which puts additional strain on the kidneys (36). As an alternative, try sparkling water, black coffee, green tea, and low-sugar smoothies (37).

Overall, drinking water is usually the best way to stay hydrated (37). A 2021 narrative review published in the European Journal of Nutrition states that water, without other additives, is the healthiest beverage (3).

Tips

Next, we’ll discuss tips that will help you decide when to drink water.
1. To make sure you are getting enough water throughout the day, drink water before and during meals and when you become thirsty.
2. Make sure to hydrate when you increase your physical activity (38).
3. Note that drinking large amounts of water infrequently will only temporarily hydrate you. This amount of water may leave the body quickly to prevent blood dilution and low sodium. Instead, do the opposite. Drink small amounts of water frequently and eat hydrating foods throughout the day (17).

Having some water in the evening will help keep you hydrated overnight. It can also decrease your body temperature to help you sleep better. However, if you have acid reflux, you might want to stop drinking water for at least 2–3 hours before you go to bed (39). Alternatively, drink only small amounts of water at bedtime to minimize the need to urinate at night.

In this section, we discussed learning to recognize your signs of hydration through thirst and urine indicators, bottled water and tap water safety, and some common myths. Next, we will summarize the critical points made in the video. Be sure to watch until the end to reinforce and help you remember each point.

Summary

In this video, you learned how water can damage your kidneys. Adequate water intake depends on your body composition, exertion level, overall health, and other factors. That’s why daily water needs vary from person to person. You might need more than 8 cups of water a day at times, and less than 8 at other times.

Advertisers claim that the drinks they market are hydrating. However, not all fluids provide adequate hydration. In fact, some contain electrolyte levels that may be too high for some people, and many contain high amounts of sugar and preservatives that may even harm kidneys over time.

Next, you learned about how important water is for your kidneys. Water loss occurs through body fluids, and replacing water is vital to effectively eliminate waste, control blood pressure, and balance electrolytes. All these effects will greatly benefit your kidney health.

Then, we emphasized that overhydration can reduce your blood sodium levels, harm your kidneys, and lead to serious consequences.

The second half of the video discussed the importance of electrolytes and when increasing their intake is necessary for hydration. Dehydration can also damage the kidneys. Too little fluid intake may cause low blood volume and impair the kidney’s filtration system. Hormones such as renin and aldosterone will attempt to restore the fluid balance. The resulting high pressures may weaken and damage the intricate filtering mechanism of the kidneys, leading to acute kidney injury. Drinking water regularly, and particularly when you are thirsty, may prevent dehydration and its negative impact on the kidneys.

Moving on, the video then discusses how to recognize personal signs of fluid balance. Helpful indicators of fluid balance are thirst and urine color. You learned how your health may depend on whether your drinking water is safe. Lastly, knowing how much and when to drink water can influence a healthy lifestyle.