Water is essential for metabolism and maintaining water balance in the body, but excessive water intake can be harmful to your health. In particular, drinking more water than your kidneys can process can cause hyponatremia, which can lead to problems with your brain, heart, and other major organs. It’s important to maintain adequate water intake.

What happened to A?

After learning that the secret to plump skin is drinking enough water, A decided to start drinking more water from that day on. She drank 1 liter of water every day, but she didn’t notice much difference in her skin. She wanted to have firm skin as soon as possible, so she gradually increased the amount of water she drank. Slowly, however, unexpected changes began to occur in her body. She felt fatigued more easily than before, sometimes her muscles felt cramped, and sometimes she complained of nausea and severe headaches. Eventually, she collapsed and was rushed to the emergency room, where she was diagnosed with a condition called hyponatremia.

Hyponatremia, caused by excess water intake

The basic structural and functional unit of the human body is the cell. Water exists inside and outside the cell, and the cell membrane separates the two spaces. Water makes up about 60% of our body weight, with one-third of it in the form of extracellular fluid and two-thirds in the form of intracellular fluid. Cell membranes are composed of phospholipid bilayers that act to restrict the movement of polar molecules. Water molecules, on the other hand, despite being polar, are small enough to freely cross the cell membrane. If there is a difference in osmolarity between the inside and outside of the cell, the water molecules will move in the direction that eliminates the difference in osmolarity, keeping the osmolarity of the two spaces equal.
Consider the situation of placing a cabbage in salty water, which increases the osmotic concentration of the extracellular fluid. This is because the first thing that the external environment affects is the fluid outside the cell, not the internal fluid. Osmotic concentration is the solute concentration of molecules and ions that determines the magnitude of the osmotic pressure. Sodium ions (Na⁺) and chlorine ions (Cl-) have the greatest effect on osmotic concentration in cells. To put it simply, osmotic concentration is the salinity of salt water. A solution with a high osmotic concentration is salty, while a solution with a low osmotic concentration is fresh. The chemical formula for salt is NaCl, and when NaCl is dissolved in water, it acts as an ion that determines the osmotic pressure.
To understand osmotic concentration, consider the following example. Imagine a container divided into two parts by a semi-permeable membrane, which does not allow the solute salt to pass through, but does allow water to pass through. This is similar to the function of a cell membrane. Suppose you put 100 grams of salt in 1 liter of water in the left compartment and 1 gram of salt in 1 liter of water in the right compartment, assuming both compartments have the same volume. Which compartment is saltier? The left compartment, of course. Therefore, we can say that the osmotic concentration is higher in the left compartment.
The reaction takes place until an ‘equilibrium’ is reached, where the difference in osmolarity disappears. If there was no semi-permeable membrane, a lot of salt from the left compartment would move into the right compartment and a lot of water from the right compartment would move into the left compartment, eventually reaching equilibrium. However, in the presence of a semi-permeable membrane, the salt particles cannot move to the other compartment because the membrane is selectively permeable to substances. While salt particles cannot pass through the membrane, water molecules can freely pass through a semi-permeable membrane due to their small size. Therefore, more water from the right compartment moves into the left compartment in order to equalize the osmotic concentration in both spaces. As a result, there is more water in the left compartment than in the right compartment.
Why is there more water in the left compartment? This is to equalize the salt concentration in the two compartments. If you have 100 grams of salt in the left compartment and 1 gram of salt in the right compartment, you would want to use 2 liters of water to equalize the concentration in both compartments. You would have to add more water to the left compartment to equalize the salt concentration in the two compartments. This is how, in the presence of a semi-permeable membrane, there will be more water in the left compartment at equilibrium.
Now let’s go back to A’s story. We’ve been talking about salt, but it’s actually sodium ions that play an important role in regulating osmotic concentration in the body. When A drank too much water, she lowered the osmolarity of the extracellular fluid too much. As the osmotic concentration of the extracellular fluid decreased, water entered the cell, causing the cell to swell.
Hyponatremia is a condition in which a large amount of water enters the cell due to a difference in osmotic concentration, preventing the cell from functioning normally. Brain cells are particularly susceptible to damage from excess water. The brain is located inside a rigid skull, so when brain cells swell, they are compressed by the skull. It’s like a pair of pants that used to be loose but become tighter as you gain weight. When brain cells are compressed, they can suffer serious damage, which is why A felt dizzy, had a headache, and eventually fell unconscious.

Treating hyponatremia by reversing the cause of the disease

The cause of hyponatremia is the rapid decrease in the osmotic concentration of the extracellular fluid, which causes an excessive amount of water to enter the cells, causing them to swell and lose their function. Cells need to maintain a certain size and osmotic pressure to function normally, and when they swell abnormally due to water imbalance, various functions are impaired. One of the most sensitive tissues to this is the brain. Unlike other cells, brain cells are trapped in the skull with little room to expand, so when they are pressurized by an excess of water, brain damage accelerates. For this reason, hyponatremia patients suffer from dizziness, headaches, and even coma.
Since this disease is caused by a difference in osmotic concentration, it can be treated by working in reverse. To normalize the osmotic imbalance, isotonic solutions are used to restore the osmotic concentration of the extracellular fluid. An isotonic solution is a solution that has the same osmotic pressure inside and outside the cell, matching the body’s natural osmotic pressure. When isotonic solutions are injected into the blood vessels, the osmotic concentration of the extracellular fluid is gradually restored, causing excess water to flow back out of the cell. In this process, the volume of the cells returns to normal, and the swollen cells regain their function.
This treatment is very important, especially in cases of hyponatremia, where rapid treatment is essential. Isotonic fluid administration is a key treatment to reduce this risk, as prolonged pressure on brain cells can cause irreversible damage. The effect of isotonic fluid administration is not just to control the size of the cells. When the osmotic concentration of the extracellular fluid is normalized, the water balance of the entire body is restored, allowing other organs and tissues to function properly. The permeability of cell membranes to substances is also normalized, restoring normal functioning of the nervous and muscular systems.
In addition to isotonic solutions, in some cases, hypertonic solutions can be used to restore the osmotic concentration of extracellular fluid more quickly. Hypertonic solutions are solutions with a higher concentration than the body’s own osmotic concentration, which allows water to move out of the cells more quickly. However, hypertonic solutions should be used with caution and professional judgment, as excessive use can cause excessive water to escape from the cells, resulting in dehydration.
Another important factor in the treatment of hyponatremia is fluid restriction. If an excessive amount of water is consumed, as in case A, the situation will worsen if more water is consumed before the body naturally flushes it out. Therefore, hyponatremia patients are restricted in their fluid intake for a period of time. This is done to normalize the water concentration in the body and restore the balance between extracellular and intra-cellular fluids.
After all, hyponatremia is caused by excessive water intake, but the way to correct it is to regulate water movement. Treatment with isotonic or hypertonic fluids is based on this principle and focuses on restoring the normal osmotic concentration of the cells. This helps to restore the water balance in and around the cells and quickly relieve the patient’s symptoms.

Too much water can be harmful

Although water plays an essential role in the body’s energy metabolism, consuming too much water can be dangerous. In addition to metabolic processes, water plays many other roles in the body, including regulating body temperature, eliminating waste, and transporting nutrients. However, no matter how important it is, too much water can be harmful to your health. Drinking too much water, especially when water metabolism is impaired, can cause the osmotic concentration of extracellular fluid to drop dramatically, leading to conditions such as hyponatremia.
The body has the ability to regulate water levels to maintain fluid balance. The kidneys play an important role in this process, and excess water that the body doesn’t need is excreted in the urine through the kidneys. However, drinking too much water in a short period of time can overwhelm the kidneys and lead to fluid imbalances. The kidneys can process about 800 milliliters (mL) to 1 liter of water per hour, and if you drink more than that, your body starts to lose balance. As excess water accumulates in the body, the osmotic pressure inside and outside the cells changes, and the cells swell due to the excessive influx of water into the cells.
Particularly problematic in this process is the dilution of the sodium concentration. Sodium is essential for maintaining electrolyte balance in body fluids and regulating nerve and muscle function. However, drinking too much water can lead to a relative lack of sodium, resulting in hyponatremia. Hyponatremia is an excessively low concentration of sodium in the body’s fluids, which can lead to a number of bodily functions. In mild cases, it can cause symptoms like headaches and nausea, but in severe cases, it can lead to coma or death.
Drinking too much water can also cause brain swelling. Unlike other parts of the body, the brain is encased in a rigid skull, leaving little room for expansion. When excess water enters the brain cells, the brain swells, increasing the pressure inside the skull, which can cause headaches, dizziness, vomiting, and vision problems. In severe cases, it can lead to neurological symptoms such as loss of consciousness, and the longer this condition continues, the greater the risk of brain damage.
Another problem is the strain it puts on the heart. Excessive fluid intake increases blood volume, which means the heart has to pump more blood. The heart has to work harder to pump this extra blood throughout the body, and in the long run, this can put a strain on the heart and increase the risk of cardiovascular disease.
Therefore, drinking the right amount of water is of utmost importance. In general, the recommended daily water intake for adults is around 2 to 2.5 liters, although this can vary depending on your activity level, weight, climate, etc. However, you should avoid drinking significantly more than this amount. Drinking a lot of water, especially in a short period of time, can put a lot of strain on your kidneys and your body’s hydration system, which can have a negative impact on your health.
In addition to this, you should consider your physical condition in order to balance your water intake. If your body doesn’t excrete water properly or you suffer from certain medical conditions, you should be more careful with your water intake. For example, people with heart failure, liver disease, or kidney failure may not be able to flush water out of their bodies efficiently, so excessive water intake can be dangerous. Therefore, it’s essential for people with these conditions to follow their doctor’s advice and regulate their water intake.
In conclusion, water is essential for maintaining good health, but it’s important to remember that drinking too much of it can be poison. As with everything, it’s best to consume water in moderation. Rather than drinking too much just because it’s important, it’s important to drink the right amount for your body and listen to your body’s signals to regulate your water intake.