Medicosnext
Hydration is basically the ability of the body to absorb water or any liquids it requires. This is primarily dependent on the amount available to the body. Apart from plain water or other liquids, 20% of hydration is achieved from the food we eat, and 80% from water or other liquid. The human body is primarily made up of 50% to 75% water, and most of this water is found inside the cells. Every cell, tissue, and organ present in our body needs water to work efficiently. Without proper hydration, the body begins to shut down and can lead to dehydration. Water is lost in the form of urine and sweat, and throughout the day when one breathes.
The best fluid for staying hydrated is water; however, there are other fluids and foods which can help in increasing one’s hydration level. Some of them are fruit-flavored water (e.g. cucumber, lemon, sweet-lime), fresh vegetable or fruit juices, tea, coffee, and milk, which can help you increase your fluid intake. Apart from them, sugar-loaded beverages like soda and packaged fruit juices also fall in the fluid category and count as a total fluid intake. However, the frequent intake of these products should be avoided, as they can affect our health. Caffeine might have the opposite impact leading to dehydration, so a high intake of caffeine must be avoided. Sports drink is another good option for hydration, particularly for athletes or the ones who perform heavy workouts, as they help the body absorb water by replacing the electrolytes. But, one should be mindful while choosing the sports drink and try to avoid the ones which are loaded with sugar, sodium, and caffeine. Energy drinks are also another category and are not same as the sports drink. It should be limited, as they contain a high amount of caffeine and ingredients (guarana, ginseng, or taurine) which over stimulate our body. Apart from all these, fruits like watermelon, all kinds of melon, berries, grapes, bell peppers, and foods like soups, broths, daal soup are actually good sources of fluid and helps boost hydration.
Proper hydration is a very important aspect of the diet, since maintaining body fluid levels helps in the normal functioning of the body. Drinking enough fluid is crucial for our body physiology, as it plays a vital role in regulating the body temperature, delivering essential nutrients, glucose, and oxygen from the bloodstream to various cells, helping the organs to function properly. It also helps in providing adequate lubrication for the joints and eyes, keeping skin healthy, aiding in digestive functions, removing waste products from the kidney, improving sleep quality, preventing infection, etc. Being hydrated also helps in improving cognition and mood.
Various factors might affect the hydration need of an individual, including age, climate, and physical activity. Our body naturally regulates body temperature. In summer, the loss of water via perspiration acts as a cooling mechanism to maintain the temperature. So, when there is more sweating, we need to balance it with more fluid intake. As we age, the level of water in our body changes, with newborns having higher levels of fluid in the body, as compared to adults, and the elderly having lower fluid levels. However, hydration is crucial for all age groups. We usually are aware of the guidelines on drinking at least two liters, or eight glasses, per day. However, whether these targets are achieved or not depends on the individual. The amount of water required daily is often average and depends on other physical factors like temperature and physical activity. The water intake usually depends on age, gender, physiological condition, illness, temperature and humidity, and physical activity levels.
Studies have stated that body water composition is indirectly related to body mass index (BMI). The fatty tissue contains less water as compared to lean tissue. Since females have more fatty tissue than men, their water content is comparatively less. Women and obese people generally experience cellular dehydration and are at risk of dehydration. The average amount of water in the human body ranges from 50-75%, whereas in the case of an adult human body, it varies between 57-60%. In the case of infants, the percent is much higher, around 75-78%, which gradually drops to 65% by one year of age. Men generally require more water than women, since they have less body fat, and usually, higher energy expenditure. Based on body composition, the water content varies between the two genders. The ideal body water composition fluctuates between 45%-60% in females and 50%-65% in males. In the case of athletes, it is recommended to have 5% more body water than the average adult. The European Food Safety Authority states that the water intake for women is 2 liters per day, and for men is 2.5 liters per day.
Dehydration
The imbalance between fluid and electrolyte intake, as well as loss in the body, is termed as dehydration. Generally, it is understood as excessive loss of water. The severity of dehydration ranges from mild to severe; however, it can be fatal if the fluid loss is more than 15% of total body water.
Pathophysiology
Our body’s water is distributed into extracellular and intracellular compartments. The extracellular compartment is one-third of total body water, while the intracellular compartment contains two-thirds of the total body. The fluid from the extracellular compartment, then the intracellular compartment, is depleted in dehydration, respectively. This depletion causes cellular shrinkage and metabolic dysfunction.
Increased water loss or decreased fluid intake or both can cause dehydration. Symptoms like impaired thirst sensation, chronic illness, fever, and sickness are common causes of decreased water intake for the elderly population. Other common causes of increased fluid loss include vomiting, diarrhea, diuresis, and sweating. Extensive working under hot weather and electrolyte replacement can also cause fluid loss.
The signs and symptoms of dehydration ranges from mild symptoms, such as increased thirst, sleepiness and tiredness, decreased urine output , headache, dry skin, and dizziness to very less urine, or no urine at all, low blood pressure, increased heart rate, seizure, and shock.
Dehydration can be classified in relation to sodium concentration in the body as in: isonatremic, hypernatremic, hyponatremic dehydration.
Isonatremic dehydration is also called isotonic dehydration. It is a condition where both water and sodium are lost, but the serum sodium concentration maintains normal serum osmolality. Serum osmolality determines the movement of fluids and electrolytes across membranes. The normal serum osmolality is 285–295 mOsm/kg. Vomiting and diarrhea and excessive sweating are major causes of isonatremic dehydration.
Hyponatremic dehydration is also called hypotonic dehydration. It is a condition when sodium loss is greater than water loss, resulting in a decrease in serum osmolality. This decrease causes water to shift from the extracellular space into the intracellular space. Hence, the cells swell and edema may occur. Hyponatremia can be acute or chronic. If sodium loss has occurred for more than 48 hours, it becomes chronic hyponatremia, this specific type of dehydration manifests as neurological symptoms ranging from headaches, nausea, lethargy, and potentially confusion to coma and death. Use of diuretics, Addison’s disease, use of hypotonic water or saline for IV, etc. are major causes of this dehydration.
Hypernatremic dehydration is also called hypertonic dehydration. It is a condition when water excreted from the body is more than that of sodium excretion, resulting in increased sodium concentration in the extracellular fluid (hypernatremia). This increase causes the blood osmolality to increase, causing water to shift from the intracellular to the extracellular space. Fever, increased water loss through urine, decreased water intake, and excessive sweating all are major causes of hypernatremic dehydration.
Over hydration
This is a condition when the body takes in more water than it loses. When people drink more water than what is required for their bodies, over hydration can occur. This excessive hydration causes low sodium levels in the blood, which can be fatal. Generally, over hydration occurs in athletes who drink more water to prevent dehydration, or because of a psychiatric disorder called psychogenic polydipsia. In people who have normal functioning of pituitary gland, heart, and kidney, drinking too much water rarely causes over hydration. It usually is common with disorder of kidney, heart, or liver, or with use of anti-depressants. It can also occur from inappropriate secretion of the anti- diuretic hormone. In this condition, the pituitary gland secretes too much anti- diuretic hormone, which causes the kidney to conserve water, hence over hydration.
