Water is an essential component in terms of having a role in building of human body. The total body water content must be adequately maintained for the health and wellbeing of an individual. Water intake as well as water loss is governed by efficacious homeostatic mechanisms which are receptive to even minute changes such as hundred milliliters. Water deficit happens as hypohydration when fluid intake is not sufficient to replace fluid losses. When water loss exceeds the amount of water consumed, dehydration results.  Mild dehydration is described as fluid loss being around 1-2% of total body fluids. Severe dehydration occurs with fluid loses over 5%. Dehydration has remarkable consequences including effect on body temperature, respiratory rate, mental functioning and muscle endurance. Overall, the role of water as a necessary nutrient is indispensable. Consequently, appropriate hydration status is extremely imperative for health and wellbeing of an individual.
The human body contains around  70% of water.¹  In terms of body weight water makes up  75%   in infants and 55% in elderly.² Water is necessary  for cellular homeostasis as well as  life.²  Still   plentiful unanswered questions  exist regarding  this extremely imperative constituent of  our body and our diet.² The water in the body has diverse physiological roles.¹ These include being required  for   breathing for oxygen  transport  to  the  cells,  metabolism,  digestion  and absorption  of  nutrients,  detoxification of the body, regulation of body temperature, upkeep  of equal osmotic pressure in cells as well as extracellular  space  etc.¹ Water should be treated  as  vital nutrient in diet. Accordingly, it is imperative for health to have total body water (TBW) content in appropriate standards.
The indicator for water intake is primarily thirst.³ The thirst sensation is managed by the central nervous system that gets signals pertinent to hydration status from central as well as peripheral pathways.³ Identical to calories, the correct amount of water to be drunk is controlled by the balance between the intake as well as the losses. The intake is by means of fluids as well as solid foods.³ From food, fruits and vegetables are the leading source of water. Water emanating from oxidation of macronutrients makes a contribution as well, though usually inconsequential.³
As an aftermath of thermoregulatory sweating body water is lost. Furthermore when fluid intake is not sufficient   to reconstitute sweat losses a water deficit results as hypohydration.⁴ Amongst  individuals   indulging in  exercise or being exposed  to warm climates as a result of  loss of sweat, acute mild as well as moderate hypohydration can be to some extent  common.⁵ This may also happen  in situations of diminished  fluid intake or as a result of  consumption of diuretics.⁵ The  loss  of  body  fluids  outstripping the  amount which  is taken in,  interrupting  the delicate equilibrium of minerals in body fluids, culminates in dehydration.¹ Mild dehydration results from body loses around  1-2% of total body fluids. Furthermore severe dehydration is investigated as  taking place when  body loses over  5% of the total fluids.¹ Likewise a heat wave that took place in Paris,  France in 2003 eventualized  in  a  2% elevation in mortality.⁶ Majority of deaths occurred in vulnerable groups and happened as a result of heat-related illnesses, such as  dehydration.⁶ As advocated by the American College of Sports Medicine (ACSM) Guidelines on Exercise and Fluid Replacement and the position of the Academy of Nutrition and Dietetics on Nutrition and Athletic Performance, dehydrated individuals should have an intake of 1.25 to 1.50 L of fluid per kilogram of body mass (BM) lost to restore  body water content, if the fluid deficit is huge  and recovery time is restricted to around  less than 12 h.⁷
Mild dehydration can happen during peculiar times in a day, due to poor hydration habits and restricted access to a variety of beverages or foods like in work environments.⁸ Overall severe dehydration curtails   performance, results in difficulties in concentrating, headache, irritability, sleepiness and elevates body temperature and respiratory rate. An acute dehydration can develop in hours.⁹ The physiological causes for poor performance as a result of dehydration encompass thermoregulation, hyperthermia, cardiovascular strain, increased glycogen utilization as well as reduced skeletal muscle blood flow.¹⁰
Regarding  hydration, it is  acknowledged that dehydration as a result of loss of body weight over 2% of initial body weight has a negative effect on the exercise performance and  undermines muscular endurance, mental functioning as well as thermal regulation.¹¹ As exhibited by research  most of the  athletes have a tendency to count  on a sense of thirst to apprise them regarding desire to drink fluids in the course of training sessions as well as  competitions.¹² Disastrously when athletes depend on a sense of thirst alone, they do not by choice  drink sufficient  fluid to avert the development of dehydration during exercise.¹² On the whole, the research demonstrates  that the sports performance of numerous  athletes is possibly being  thwarted by inadequate   hydration habits.¹²
Hydration status can have an effect on the pharmacodynamic as well as pharmacokinetic properties of medication.⁷ A distorted hydration state, notably dehydration, has been revealed to have a brunt on kidney function. Additionally this  can disturb  the safety and efficacy of a few  drugs, peculiarly those having  a narrow therapeutic range, including   lithium.⁷  It was documented in a study by Strippoli et al  that inverse relationship exists  between water intake as well as  the risk of having chronic  kidney disease , such that individuals having an intake of  3.2L of fluid a day having lower risk in contrast to  those having consumed 1.8L in a day.⁷
The brain’s decision to commence or halt drinking as well as to select the suitable drink is done before the ingested fluid reaches the intra and extracellular compartments.² Messages are sent from the taste buds in the mouth to the brain regarding the nature   of the ingested fluid. The neuronal responses are elicited as though the coming in water had by that time reached the bloodstream.² Drinks are also used up for their energy content including soft drinks and milk. Also in warm weather drinks are utilized for cooling and in cold weather for warming. Drinking like this is suggested as being moderated via the taste buds, that communicate with the brain in a rather reward system and their   mechanisms are merely in initiation to be understood. This bias by means of which   human beings rehydrate themselves can be beneficial as it permits water losses to be regained prior to occurrence of thirst-producing dehydration.² Regrettably this bias is also coupled to adverse circumstances. In relation to beverages the dominant  concerns are their energy content and their ramifications on dental health.¹³ Due to obesity levels perpetually surging, it is essential for greater part of population to control their energy intake and  foods also  must be given due consideration  for their energy content. Concerning dental health there are two issues, dental caries as well as dental erosion.¹³ Water intake suggestions by Institute of Medicine (IOM) and European Food Safety Authority (EFSA) on the whole range from 2–2.7 L/day for adult females and 2.5–3.7 L/day for adult males.¹⁴ As with other essential substances, suggestions for water intake are provided by various authoritative bodies.¹⁴
Water balance is adjusted by delicate as well as  meticulous  homeostatic mechanisms that control water intake as well as  losses.² Insufficiency  or overload of precisely  a meager hundred milliliters activate these mechanisms and  as  small as losses of around 1% of body water  will be amended  in 24 hours.² Our health can be put in jeopardy as a result of shortfalls in body water, if they culminate in sizable  disruption  in  water balance.¹³  In order to accomplish   needs,  humans cannot acquire  sufficient   amount of required  water by metabolism or get  adequate  water by means of  food ingestion.¹⁵ Consequently , it is necessary  to pay attention to what we drink in the entire  day to make sure  that we catch  up with  our daily water needs, as failure to do so can   lead to  negative health effects. Water is fundamental for life.¹⁵ Without water, humans can survive only for days.²

How to cite this: Junejo S, Hoor T, Riaz M. Appropriate Hydration Can Make a Difference. Life and Science. 2022; 3(1): 63-65.  doi: http://doi.org/10.37185/LnS.1.1.214