NUTRITION AND HYDRATION: THE ROLE OF WATER IN BODY SYSTEMS
Everyone knows that water plays a vital role in survival. Without water, the human body cannot function at its very basic level. Even a 1% water loss – ie, mild dehydration – has negative effects on physical and mental health.1 In light of Nutrition and Hydration week this month, how can we ensure that everyone is adequately hydrated, and why should we do so? Water is the chief constituent of humans, making up 60% of a woman’s body and 50-55% of a man’s body.1 In developed countries, we are very fortunate to have safe drinking water, which is still not accessible in many developing nations. When thinking of hydration, one should not neglect the fact that there is hydration in the food we eat, which constitutes about 20% of daily water intake,1 and in drinks such as teas, coffees and juices (alcohol does not count towards this). The general guideline is around six to eight glasses (1.5-2 litres) a day.2 Eight glasses of water are not always necessary for everyone, as we get a good proportion of fluids elsewhere in our diet. Exceeding recommended guidelines, however, can result in water toxicity, cases of which have been rare and isolated, but often fatal.3 Still, between six to eight glasses per day remains a good standard. THE IMPORTANCE OF STAYING HYDRATED
The sensation of thirst is felt when you are already slightly dehydrated, so it is important to drink regularly throughout the day to avoid this, monitoring and adjusting fluid intake especially when you feel thirsty. Despite this, evolutionarily, humans know to expect hydration and correction of fluid deficits following exercise with their next meal, so fluid balance does not need to be regulated at every
moment.3 Appropriate hydration is important in maintaining healthy skin, thermoregulation of body temperature, reducing the instance of constipation, kidney and bladder issues, as well as reducing the risk of urinary tract infections (UTI), avoiding headaches, fatigue, confusion and irritability.4 The NHS launched a campaign with the tagline, ‘Eat well, drink well and keep the skin well’ in order to encourage proper hydration to prevent skin ulcers, or bedsores, from forming, especially in bed-bound individuals and hospital patients.5 Adequate hydration is also shown to have a positive effect in preventing falls in elderly people.6 Thinking of water and fluid intake often seems mundane and only complementary to a stimulating and varied diet, but hydration is crucial for the overall body system to function in such a way that supports diet and lifestyle. Hydration can be seen as fundamental to a healthy diet.
COVER STORY
Farihah Choudhury Health and Wellbeing Co-ordinator, University of Southampton Farihah is a Prospective Master’s student of Nutrition for Global Health. She is interested in public health nutrition, particularly in changing population health patterns as a result of dynamic food environments, food security and food waste, food poverty, food marketing and literacy.
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SWEATING IT OUT
In hot summer months, or when conducting heavy physical exercise, it is vital to drink extra fluids to replace those that are lost, due to perspiration, and to prevent heat exhaustion and heatstroke through overheating.7 Some athletes choose to rehydrate with isotonic fluids, to replace not only perspired water, but electrolytes such as sodium and potassium, and www.NHDmag.com March 2019 - Issue 142
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PUBLIC HEALTH
Children and young infants have a higher proportion of bodily water, are less tolerant of heat and are more likely to get dehydrated faster.
sugar for energy. However, the use of such sports drinks for all sports is contentious and it is suggested that athletes need not consume special sports drinks in lieu of water unless they are exercising for over 90 minutes consecutively, or are drinking high volumes of water. Sports drinks are designed to replace loss of excessive electrolytes, which can lead to mild or serious hyponatraemia (low sodium) if left unchecked. Loss and imbalance of electrolytes occurs through perspiration and drinking larger than normal volumes of water.1 HYDRATION IN INFANTS AND CHILDREN
Children and young infants have a higher proportion of bodily water, are less tolerant of heat and are more likely to get dehydrated faster.1 Children naturally take less responsibility for their diets, which includes drinking water frequently, so it is vital to encourage them to drink the appropriate amount to support proper growth and development, as well as avoid any malaise. Encourage children to drink throughout the day with a fun water bottle, and ensure a drink is provided at all meal times. ENSURING THE LESS ABLE HAVE AN APPROPRIATE FLUID INTAKE
Although drinking water throughout the day usually comes as second nature to those of us 10
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who are able-bodied, or in good general health, it is harder for others to track their hydration. This includes the elderly, bed-bound individuals, or poorly individuals with, for example, incontinence, dementia or depression. Moreover, those who are acutely ill often have temporarily higher energy requirements while they recover, so it is fundamental to their full recovery that adequate hydration is taken. Healthcare professionals and carers are encouraged to tackle barriers to adequate hydration by ensuring enough fluid is available at mealtimes, as well as making an ‘event’ of it, such as hosting a social event such as a tea party or coffee morning. Social interaction should be encouraged, as this is thought to promote fluid intake.8 Furthermore, for those at risk of dehydration, plenty of hydrating foods should be administered including fruit, vegetables, stews and soups.5 Between 10 to 60% of elderly patients are admitted to hospital undernourished.9,10 This can be due to multiple reasons such as chronic disease, or decline due to the inability to cook and prepare food, or food poverty. Loneliness too can entail a lack of support or motivation for eating, for example, through the death of a spouse, or separation from family. Furthermore, repeat hospital visits may contribute to physical decline, as patients often find the food unappealing and unappetising, a
This material is for healthcare professionals only.
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Reference: 1. Canani RB et al. J Pediatr 2013;163:771–777. Nutramigen with LGG® is a food for special medical purposes for the dietary management of cow’s milk allergy and must be used under medical supervision. Nutramigen with LGG® is not recommended for premature and immunocompromised infants unless directed and supervised by a healthcare professional. IMPORTANT NOTICE: Breastfeeding is best for babies. The decision to discontinue breastfeeding may be difficult to reverse and the introduction of partial bottle-feeding may reduce breast milk supply. The financial benefits of breastfeeding should be considered before bottle-feeding is initiated. Failure to follow preparation instructions carefully may be harmful to your baby’s health. Parents should always be advised by an independent healthcare professional regarding infant feeding. Products of Mead Johnson must be used under medical supervision. *Trademark of Mead Johnson & Company, LLC. © 2018 Mead Johnson & Company, LLC. All rights reserved. LGG® and the LGG® logo are registered trademarks of Valio Ltd, Finland. Date of preparation: September 2018 UK/NUT/18/0060i
PUBLIC HEALTH feeling which is exacerbated by illness. Staff shortages combined with a lack of bespoke care often leads to difficulty in eating for those who are not physically or mentally able to feed themselves. In order to ensure these patient groups receive both calorie-rich and hydrating foods (that are also appealing), menu items that might otherwise seem indulgent or unhealthy (such as jellies, custards, milkshakes and hot chocolate), are crucial for carers and hospital staff to administer to ensure undernourishment and dehydration are avoided.11 In addition, when their ability to make choices might be otherwise compromised, aged people take pleasure in being able to choose their own drinks, so it is important to have a range of drinks on offer, from water, to squash and milk.12 CASES OF OVER-HYDRATION
Unfortunately, there have been rare isolated incidents of over-hydration which have been fatal. Usually this has been an athlete or sportsperson who has overestimated their fluid needs, leading to water intoxication, which occurs as a result of an imbalance of electrolytes following excessive water intake. This is known as exercise-associated hyponatraemia (EAH).13 Incidents have also occurred during water drinking competitions, or when taking drugs that can increase the feeling of thirst, such as ecstasy. Hyponatraemia - low sodium levels - can lead to water entering the brain and causing cerebral oedema. It has been estimated that one sixth of marathon runners develop mild hyponatraemia,14,15 which can be ameliorated by drinking sports beverages, or reducing slightly the amount of water ingested. Cases of extreme over-hydration are rare. In 1993, the first recorded case of a death from water intoxication was following the hospitalisation of seven runners at the Valley of Giants marathon in 1993.13 All seven were
taken ill after the marathon, due to pulmonary oedema. After treatment in hospital, one runner still had unsuspected hyponatraemic encephalopathy and died shortly after. In 2007, 28-year-old Californian mother Jennifer Strange was found dead in her home after entering a challenge on a radio station, whereby she was instructed to drink as much as possible without urinating in order to win a Nintendo Wii system. After complaining of a headache to colleagues, she is thought to have collapsed in her house. The first reported case of acute cerebral oedema due to hyponatraemia, resulting in a fatality, occurred in 2008 when a healthy 47-year-old English woman completed a five-hour hike spanning 10km in the Grand Canyon National Park, Arizona.14 She collapsed shortly after. Her husband recalled that she drank a lot of water and ate very little food. Initially, she fell face forward onto concrete, but regained consciousness; her condition quickly deteriorated after vomiting large amounts of fluids and she died 19 hours after her initial fall. SUMMARY
Appropriate and plentiful hydration is a firm foundation for a healthy diet and ensures that we are functioning at our optimum. The current guidelines of six to eight glasses of water a day can be adjusted due to the target group, but is a good standard to follow, to ensure the correct water intake. Different groups have different requirements and some groups face barriers to hydration that can be overcome with the help of carers and healthcare professionals. Over-hydration leading to fatalities is rare, but has been documented in the past and must be monitored, especially in those who are most at risk of over-stepping their fluid intake, ie, those performing high intensity or duration exercise.
Nutrition and Hydration Week - 11th to 17th March 2019 is a yearly initiative that has taken place every March since 2012 to highlight and tackle issues of dehydration. It encourages organisations to put on events that emphasise the importance of appropriate nutrition and water intake.
For more information, visit: www.nutritionandhydrationweek.co.uk 12
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