Water is essential for life, without it human can only survive for days. Water is also an essential component of all body tissues (Mahan & Stump, 2004). The total body water in fat people is lower than normal people because the amount of body water in fat is less than muscle. According to Santoso et. al. (2012), the detail water percentages of body weight (BW) in human are as follows:
– Preterm baby: 80% of BW
– Normal baby: 70-75% of BW
– Before puberty: 65-70% of BW
– Adult: 50-60% of BW
As the essential nutrient, water has important functions as follows:
– Former of cell & body fluid
– Regulator of body temperature
– Solvent for ions & nutrients
– Lubricants & insulator
– Media for transportation
– Media for toxin & metabolite elimination
Water Loss & Requirement
There are 2 types of water loss:
– Sensible water loss à excreted through urine & feces
– Insensible water loss à excreted through lungs & skin
The balance of water (input & output) can be seen in the below table (Guyton et. al, 2006):
|
Normal (ml/day) |
During hard activities |
|
| INPUT | ||
| From food & drink |
2100 |
|
| From Metabolism |
200 |
200 |
|
2300 |
200 |
|
| OUTPUT | ||
| Skin |
350 |
350 |
| Respiratory |
350 |
650 |
| Sweat |
100 |
5000 |
| Feces |
100 |
100 |
| Urine |
1400 |
500 |
|
2300 |
6400 |
|
| TOTAL |
6600 |
6600 |
The symptoms of dehydration is as follows:
|
% BW Loss due to Dehydration |
Symptoms |
|
1-2 |
Strong thirst, loss the ability to taste, discomfort |
|
3-5 |
dry mouth, less urinating, hard to concentrate, hot skin, tremor, impatient, sleepy, vomit, emotionally unstable |
|
6-8 |
Increase body temperature, increased pulse & breath, headache, difficult to breath, weak muscle |
|
9-11 |
Seizure, hallucination, swollen tongue, weak balance & circulation, renal failure, decreased volume & blood pressure |
Basically, factors for water requirements depends on:
– Temperature (body & environment)
– Physical activity (intensity & duration)
– Body size
– Other Physiologic condition (ex: Elderly, pregnancy & lactation)
For adults, water requirement is approximately 2 litres in 24 hours. While we’re in cool environment, sometimes we don’t feel thirsty but actually we need more water than in normal temperature. Therefore, we need to drink even before we feel thirsty. For athletes, water requirements also need to be adjusted according to intensity & duration of sports.
For children, there are 3 methods to calculate water requirement/day:
– Based on Darrow formula:
* BWt<10kg = 100 ml/kg BW
* BW 10-20kg = 1000 ml + 50 ml/BW increased >10 kg
* BW >20 kg = 1500 ml + 20 ml/BW increased >20 kg
– Based on body surface (1500 mL/m2 body surface)
– Based on amount of liquid excretion (∑ urine + insensible water loss*)
Based on AKG 2004, water requirement for Indonesian can be categorized as follows:
|
Age Group |
Water requirement (L/day) |
| Baby 0-6 months (given as ASI only)7-12 months |
0.8 1.0 |
| Children1-3 years4-6 years7-9 years |
1.1 1.4 1.6 |
| Men10-12 years13-15 years16-18 years
19-29 years 30-49 years 50-64 years 65+ years |
1.8 2.1 2.2 2.5 2.4 2.3 1.5 |
| Women10-12 years13-18 years19-64 years
65+ years |
1.9 2.1 2.0 1.5 |
For pregnancy & lactation, amount of water requirement can be based on:
– RDA (Recommended Daily Allowance)
– Calorie food consumption (1-1.5 ml/calorie consumed)
Based on RDA, the recommendation is as follows:
|
PREGNANCY |
LACTATION |
| – Rehydration | – Rehydration |
| – Support fetus nutrient circulation | – Fulfill her children’s nutrition need. |
| – Stability of Amnion | |
| – Increased blood volume | |
| – Physiologic urine incontinence |
For elderly, there are some physiological changes such as decreasing of body water, GFR (glomerular filtration rate), urine concentration ability, sensitivity to thirst, water filtration ability & aldosterone, and increasing of ADH (Antidiuretic Hormone) plasma & ANP (Atrial Natriuretic Peptide). Those physical changes can increase the risk of hyponatremia that lead to sleepy, tired, Step disorder, bone fracture, unconscious, brain damage & death. To prevent those risks, water requirement for elderly need to be reduced to 1-1.5 L/day (21 ml/kg body weight).
Diseases related to hydration status
Neither water deficiency nor overdose are good for your health. When deficiency can lead to dehydration, overdose can lead to intoxication. There are some cases for both dehydration & intoxication. For example, in Camp Verde Arizona (2009), several people died due to extreme dehydration (heat stroke), while Jennifer Strange died of brain edema in Radio Sacramento, California (2007) due to intoxication after drinking 6L of water in 3 hours.
Here is some Chronic Diseases related to hydration status (Popkin, et. at. 2010):
| Chronic Disease | Evidence Level* | Findings |
| Urolithiasis | Strong | Increased urine volume from increased fluid intake reduces stone recurrence. Favorable associations between increased hydration status and lower stone recurrence rate. |
| Bronchopulmonary Disorders | Strong | Exercise related asthma is linked with low fluid intake. |
| Hypertonic Dehydration in Infants | Less strong | In infants with gastroenteritis, a high urine osmolality due to a high protein and sodium content of formula and weaning foods increases the risk of hypertonic dehydration |
| Diabetic Hyper glycemia and Ketoacidosis | Less strong | In diabetics, experimentally induced dehydration promotes development of hyperglycemia. Higher serum osmolality at time of hospital admission was the most important predictor of death in children with diabetic ketoacidosis. |
| Morphological and Functional Changes in the Kidney | Weaker | In patients with polycystic kidney disease and chronic renal failure, sustained high urine volumes with urine osmolalities below plasma osmolality accelerate the decline of glomerular filtration rate. |
| Hypertension | Weaker | In diabetic patients, lower urine flow and sodium excretion rates are associated with higher blood pressure during the day and a reduced fall in blood pressure at night. In a study of 1688 healthy men, a low urine production day-to-night ratio was not associated with hypertension. In one study, eight male hypertensive volunteers and eight controls were exercised in a hot environment with or without water ingestion. In hypertensive men, water ingestion increased exercise-related differences in their systolic and diastolic blood pressure. |
| Fatal Coronary Heart Disease | Weaker | High intake of water is associated with lower risk of fatal heart disease. |
| Venous Thromboembolism | Weaker | High serum osmolality after stroke is associated with increased rate of thromboembolism. |
| Cerebral Infarct (Stroke) | Weaker | Increased serum osmolality or hematocrit is associated with increased risk of stroke morbidity/mortality. Stroke patients with initial mid-range hematocrit have better discharge outcomes. |
| Dental Diseases | Weaker | Salivary output decreases with dehydration. Hypohydration may be linked with dental disease. |
| Urinary Tract Infection (UTI) | Weaker | Occurrence of UTI is associated with low fluid intake or low urine output. No definitive evidence links susceptibility to UTI to fluid intake. |
| Bladder and Colon Cancer | Inconsistent | Generally show no association between fluid intake and cancer risk or tumor recurrence. |
| Gallstone | Speculative | Water intake induces gallbladder emptying suggestive that a high daily water intake may prevent gallstone formation. |
| Mitral Valve Prolapse | Speculative | Mitral valve prolapse developed after dehydration in one in 10 healthy men. |
| Glaucoma | Speculative | Dehydration reduces intraocular pressure and elevated colloid osmotic pressure.Intraocular pressure increases minutes after water ingestion and remains elevated above baseline for up to 45 minutes post-ingestion. |
Dehydration during pregnancy (hypovolemia) also can lead to effects as follows:
|
Acute Mild Hypovolemia |
Chronic Mild Hypovolemia |
| – Oligohydramnios- Birth overdue- Fetus disturbance | – Urolithiasis- Urinary Tract Infection- Constipation- Hypertension
– Vein tromboembolism |
Have you had enough today?
According to explanation above, you know that water is undoubtedly the most important nutrient. It’s very important to ensure that you are well hydrated. There are several methods can be used for measuring hydration. The comparison of those methods can be seen in the below table:
|
Methods |
Cost |
Time for analysis |
Expertise |
Accuracy |
Equipment portability |
Subject risk |
|
Urine Specific Gravity |
Medium |
Short |
Medium |
Medium |
Yes |
Low |
|
Urine osmolality |
High |
Short |
Medium |
Medium |
No |
Low |
|
Decreasing of BW |
Low |
Short |
Minimum |
Medium |
Yes |
Low |
|
24 hours urine |
Low |
Long |
Minimum |
Medium |
No |
Low |
|
Urine color |
Low |
Short |
Minimum |
Medium |
Yes |
Low |
|
Thirsty feel |
Low |
Short |
Minimum |
Low |
Yes |
Low |
From all the methods above, the color of urine is the simplest way to find out whether you have drink enough today. Below is the urine color chart you can use as indicator:
Based on above chart, you need to drink more if your urine color falls below hydrated category. In the other hand, you know that you have drink enough when your urine color matches with hydrated category.
In summary, this article attempt to provide some sense of the importance of water to our health. Water is essential to our survival and civilizations. Hopefully this article will increase our awareness about water for human health.
REFERENCES:
Guyton, Arthur, C. Hall, John, E. 2006. The Body Fluids & Kidney. Textbook of Medical Physiology. 11th Edition. USA: Elsevier.
Mahan, K. & Stump, S.E. 2004. Krause’s Food, Nutrition & Diet Therapy. 11th Edition. USA: Elsevier.
Popkin, B. M., D’Anci, K. E. D., Rosenberg, I. H. 2010. Water, Hydration and Health. Nutr Rev. 68(8): 439-458.
Proboprastowo, S. M., Dwiriani, C.M., Angka Kecukupan Air dan Elektrolit. 2004. Jakarta: WNPG VIII-LIPI.
Santoso, B. I., Hardinsyah, Siregar, P., Parede, S. O. 2012. Air Bagi Kesehatan. Edisi 2. Jakarta: Centra Communication.