Hydration and health

Afrom SEFYMEN

Increased water intake has been shown to improve cognitive function and mood in children and adults. It can also enhance educational attainment and performance in the workplace.

People who consume low volumes of water are at a higher risk of kidney disease, obesity and metabolic disorders, including type‑2 diabetes and cardiovascular disease.

Water is the healthiest “drink”, and greater water consumption would result in better health, with the corresponding cost‑benefit implications for health systems.

Historically, interest – and therefore research – on hydration focused mainly on its effect on exercise and overall organism performance, as well as its role in clinical conditions.

Research now shifts to the importance of hydration for health, concerning the amount and types of fluids consumed (1).

There is now a wealth of evidence linking adequate hydration with improved mental and physical health.

The health areas under investigation include mental health – cognition and mood – kidney health and metabolic health, i.e. obesity, type‑2 diabetes and cardiovascular disease.

The database that has been compiled is now at a stage where it can be taken into account in public‑health policy making to encourage greater water consumption and moderate intake of sugary drinks (Sagar Sweetened Beverages), with the aim of reducing chronic diseases such as obesity (2).

Given that a significant number of adults and children in Europe do not drink enough water to meet the recommendations of the European Food Safety Authority (EFSA) (3–5), it is vital that any issue relating to physical and mental health affected by insufficient hydration receives the necessary focus, promoting increased water intake.

Cognitive function

Studies have shown that dehydration in children, as indicated by urinary biomarkers, is associated with poorer cognitive performance, including reduced memory and attention (6).

Several interventions have demonstrated that increasing water intake in school‑aged children improves cognitive performance (7–9).

This is particularly important as many studies reveal that children are often dehydrated in the morning when they arrive at school (10,11).

Since children spend up to half of their waking hours at school, it is concerning that during the time they are there they consume only 14 % of the total fluid intake required, as recent research has shown (12).

On this basis, the European Commission has developed a toolkit (13) that is available to help promote water consumption in schools.

However, while the toolkit provides clear guidance on the necessary interventions, it is essential that it is supported and implemented in all European schools to optimise pupils’ performance.

Regarding the negative impact of dehydration on cognitive function in adults, there is considerably more evidence, the latest being a meta‑analysis that shows dehydrated adults suffer deficits in concentration, executive function and motor coordination (14).

Adequate hydration is also shown to improve mood (15–17).

It is clear that optimising mental health is important for people’s wellbeing as well as for workplaces. Impaired cognition will affect work performance (18) and can pose safety risks, for example when operating machinery.

The recent COVID pandemic has required health‑care workers to wear protective equipment for long periods, often causing excessive sweating and leaving limited opportunities to rehydrate. Maintaining good hydration is essential to prevent reduced cognitive performance and fatigue in this vulnerable segment of the workforce (19).

Kidney health

Chronic kidney disease (CKD) (20), kidney stones (21) and urinary‑tract infections (22) represent significant burdens to patients’ health and wellbeing, as well as to the financial cost of health‑care systems. For example, the incidence and prevalence of nephrolithiasis are rising in Europe (21), with a clear impact on health‑care expenditure (23).

There is now clear evidence that increasing water intake inhibits the formation of crystals that develop into kidney stones, thereby preventing both the primary and recurrent occurrence of nephrolithiasis (24‑26).

The European Urology Association (27) now recommends increasing the amount of water consumed for the secondary prevention of kidney stones.

The rise in obesity and type‑2 diabetes across Europe is also accompanied by an increase in the prevalence of CKD and kidney stones.

While preventing and managing obesity at a population level is challenging, higher water intake appears to be an easy and cost‑effective way to substantially improve the associated renal disease.

Contemporary population‑observational studies have shown that high water/ fluid intake can reduce the risk of chronic kidney disease (CKD) by up to 50 % (28).

Similarly, cohort studies (studies of groups of people sharing a characteristic) have demonstrated that high water intake has a protective role in renal function (29).

Current studies are exploring whether increased water intake can prevent the progression of chronic kidney disease (CKD) in patients (30).

Urinary‑tract infections account for more than half of primary‑care visits and are the most common healthcare‑associated infection in Europe (22).

As has become common in public perception, health advice has always been linked to increasing water intake, even though until recently there was little evidence to support it.

However, a recent randomised controlled trial showed that higher water intake significantly reduced the risk of recurrent urinary‑tract infection (31).

It is essential that health policies reflect the research so that the public is aware of the benefits of water consumption for mitigating these renal disorders and, consequently, reducing healthcare costs.

Metabolic diseases

Adults can maintain their body‑water volume within a wide range of intakes, including low‑volume consumption.

Nonetheless, it has been suggested that those who drink small amounts of water are under‑hydrated (32,33), with associated increases in vasopressin (AVP) (34‑36), a hormone that is integral to the body's water‑regulation processes. Elevated circulating AVP levels have further been linked to a higher risk of metabolic disease, including obesity, type‑2 diabetes and cardiovascular disease (32,37).

Beyond these chronic conditions, a large national‑sample analysis recently showed that dehydration was associated with a high mortality rate (38).

Given that a significant number of adults and children in Europe do not hydrate sufficiently to meet recommended adequate intakes, many are likely to be low‑volume drinkers and therefore at risk of metabolic disease.

This may add an extra burden for those already at increased metabolic‑disease risk due to regular consumption of sugar‑sweetened beverages (SSB).

Types of fluids

While all fluid intake can be counted towards total daily consumption, water is the healthiest and usually the cheapest way to stay hydrated.

For example, a water‑based and milk‑based drinking pattern has been shown to improve hydration compared with a standard hydration pattern based on sugar‑sweetened beverages (SSB) and other drinks rather than water (39).

As obesity prevalence rises, it is important to consider the energy content of drinks, including fruit juices and sugar‑sweetened beverages (SSB).

Research in adults across seven European countries showed that drink‑derived energy intake in each country exceeded the WHO recommendation of < 10 % of energy from free sugars (3).

Consumption of sugar‑sweetened beverages (SSB) is linked to an increased risk of obesity, type‑2 diabetes and cardiovascular disease (40).

Systematic reviews have highlighted the dose‑response relationship between sugar‑sweetened beverage (SSB) intake and coronary heart disease, type‑2 diabetes and hypertension (41‑43).

With rising obesity and related non‑communicable diseases in Europe, it is important to examine the role that healthy hydration can play in curbing these health conditions.

Water is natural and calorie‑free. Promoting increased water consumption would improve health, with clear cost‑benefit implications for health systems.

Summary

Adequate hydration is clearly beneficial for both mental and physical health. Promoting good hydration and healthy drinking habits through appropriate campaigns that target behaviour change in hydration will undoubtedly result in health benefits and increased performance and safety at school and in the workplace. Increasing fluid intake among people who currently consume small amounts – a large proportion of the European population – is likely to reduce metabolic disease and kidney disease. This would in turn lower healthcare costs for providers and improve individuals’ health and quality of life. In fact, it has been estimated that if 100 % of the population drank 2 litres of water a day, more than €250 million would be saved each year. Even if 25 % complied, the saving would still be substantial (44). The recommendation to increase water intake is a simple message, but it requires significant support from authorities and policy changes to facilitate such behaviour.

References

1. Perrier ET. Shifting Focus: From Hydration for Performance to Hydration for Health. Ann Nutr Metab [Internet]. 2017;70(1):4–12.
2. Blake MR, Lancsar E, Peeters A, Backholer K. The effect of sugar-sweetened beverage price increases and educational messages on beverage purchasing behavior among adults. Appetite. 2018;126:156–62.
3. Ferreira-Pêgo C, Guelinckx I, Moreno LA, et al. Total fluid intake and its determinants: cross-sectional surveys among adults in 13 countries worldwide. Eur J Nutr. 2015;54(2):35–43.
4. Iglesia I, Guelinckx I, De Miguel-Etayo PM, et al. Total fluid intake of children and adolescents: cross-sectional surveys in 13 countries worldwide. Eur J Nutr. 2015;54:57-67.
5. EFSA. Scientific Opinion on Dietary Reference Values for water. EFSA J. 2010;8(3):2–3.
6. Pross N. Effects of Dehydration on Brain Functioning: A Life-Span Perspective. Ann Nutr Metab. 2017;70(Suppl1):30–6.
7. Edmonds CJ, Burford D. Should children drink more water?. The effects of drinking water on cognition in children. Appetite. 2009;52(3):776–9.
8. Khan NA, Westfall DR, Jones AR, et al. A 4-d Water Intake Intervention Increases Hydration and Cognitive Flexibility among Preadolescent Children. J Nutr. 2019;149(12):2255–64.
9. Benton D, Burgess N. The effect of the consumption of water on the memory and attention of children. Appetite. 2009;53(1):143–6.
10. Bonnet F, Lepicard EM, Cathrin L, et al. French Children Start Their School Day with a Hydration Deficit. Ann Nutr Metab. 2012;60(4):257–63.
11. Michels N, Van den Bussche K, Vande Walle J, De Henauw S. Belgian primary school children’s hydration status at school and its personal determinants. Eur J Nutr. 2017;56(2):793–805.
12. Morin C, Gandy J, Moreno LA, et al. A comparison of drinking behavior using a harmonised methodology (Liq.In7) in six countries. Eur J Nutr. 2018;57:101-112.
13. Storcksdieck Genannt Bonsmann S, Mak TN, Caldeira S, Wollgast J. How to promote water intake in schools: A toolkit. Acta Paediatr Int J Paediatr. 2016;106:34.
14. Wittbrodt MT, Millard-Stafford M. Dehydration Impairs Cognitive Performance: A Meta-analysis. Med Sci Sports Exerc. 2018;50(11):2360–8.
15. Pross N, Demazières A, Girard N, et al. Effects of changes in water intake on mood of high and low drinkers. PLoS One. 2014;9(4).
16. Suh H, Lieberman HR, Jansen LT, Colburn AT, et al. Cellular dehydration acutely degrades mood mainly in women: a counterbalanced, crossover trial. Br J Nutr. 202;125:1092-1100. e
17. Pross N, Demazieres A, Girard N, et al. Influence of progressive fluid restriction on mood and physiological markers of dehydration in women. Br J Nutr. 2013;109:313–21.
18. Kenefick RW, Sawka MN. Hydration at the work site. J Am Coll Nutr. 2007;26(5):597S-603S.
19. Mustofa ND, Sabdullah PHK, Fajardo ASVS, et al. Hydration and nutrition concerns among healthcare workers on full personal protective equipment (PPE) in Covid-19 wards. Clin Nutr ESPEN. 2020;40:616.
20. Bikbov B, Purcell CA, Levey AS, et al. Global, regional, and national burden of chronic kidney disease, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2020;395(10225):709–33.
21. Osther PJS. Epidemiology of Kidney Stones in the European Union. In: Talati J., Tiselius HG., Albala D. YZ, editor. Urolithiasis [Internet]. London: Springer London; 2012. p. 3–12.
22. Medina M, Castillo-Pino E. An introduction to the epidemiology and burden of urinary tract infections. Ther Adv Urol]. 2019;11(6):175628721983217.
23. Canvasser NE, Alken P, Lipkin M, et al. The economics of stone disease. World J Urol. 2017;35(9):1321–9.
24. De La Guéronnière V, Le Bellego L, Jimenez IB, et al. Increasing water intake by 2 liters reduces crystallisation risk indexes in healthy subjects. Arch Ital di Urol e Androl. 2011;83(1):43–50.
25. Kavouras SA, Suh HG, Vallet M, et al. Urine osmolality predicts calcium-oxalate crystallisation risk in patients with recurrent urolithiasis. Urolithiasis. 2021;49:399-405.
26. Xu C, Zhang C, Wang XL, et al. Self-fluid management in prevention of kidney stones: A PRISMA-compliant systematic review and dose-response meta-analysis of observational studies. Med (United States). 2015;94(27):e1042.
27. Türk C, Neisius A, Petrik A, et al. EAU Guidelines on Urolithiasis. Eur Assoc Urol Available at https://uroweb.org/guideline/urolithiasis/ Accessed Octber 2021.
28. Strippoli GFM, Craig JC, Rochtchina E, Flood VM, Wang JJ, Mitchell P. Fluid and nutrient intake and risk of chronic kidney disease. Nephrology. 2011;16(3):326–34.
29. Sontrop JM, Dixon SN, Garg AX, et al. Association between water intake, chronic kidney disease, and cardiovascular disease: A cross-sectional analysis of NHANES data. Am J Nephrol. 2013;37:434–42.
30. Clark WF, Sontrop JM, Huang S-H, et al Hydration and Chronic Kidney Disease Progression: A Critical Review of the Evidence. Am J Nephrol. 2016;43(4):281–92.
31. Hooton TM, Vecchio M, Iroz A, Tack I, Dornic Q, Seksek I, et al. Effect of Increased Daily Water Intake in Premenopausal Women with Recurrent Urinary Tract Infections: A Randomised Clinical Trial. JAMA Intern Med. 2018;178(11):1509–15.
32. Perrier ET, Armstrong LE, Bottin JH, et al. Hydration for health hypothesis: a narrative review of supporting evidence. Eur J Nutr. 2020;60:1167-1180.
33. Kavouras SA. Hydration, dehydration, underhydration, optimal hydration: are we barking up the wrong tree? Eur J Nutr. 2019;58(2):471–3.
34. Perrier E, Vergne S, Klein A, et al. Hydration biomarkers in free‑living adults with different levels of habitual fluid consumption. Br J Nutr. 2013;109(9):1678–87.
35. Lemetais G, Melander O, Vecchio M, ET. Effect of increased water intake on plasma copeptin in healthy adults. Eur J Nutr. 2017;57:1883-1890.
36. Guelinckx I, Vecchio M, Perrier ET, Lemetais G. Fluid Intake and vasopressin: Connecting the dots. Ann Nutr Metab. 2016;68(2):6–11.
37. Armstrong LE, Muñoz CX, Armstrong EM. Distinguishing low and high water consumers—a paradigm of disease risk. Nutrients. 2020;12(3).
38. Stookey JD, Kavouras SΑ, Suh H, Lang F. Underhydration Is Associated with Obesity, Chronic Diseases, and Death Within 3 to 6 Years in the U.S. Population Aged 51‑70 Years. Nutrients. 2020;12(4):905
39. Bougatsas D, Arnaoutis G, Panagiotakos DB, et al. Fluid consumption pattern and hydration among 8–14 year‑old children. Eur J Clin Nutr. 2017;72:420-427.
40. Malik VS, Hu FB. Health : An Update of the Evidence. Nutrients. 2019;11(1840):1–17.
41. Bechthold A, Boeing H, Schwedhelm C, et al. Food groups and risk of coronary heart disease, stroke and heart failure: A systematic review and dose‑response meta‑analysis of prospective studies. Crit Rev Food Sci Nutr. 2019;59(7):1071–90.
42. Schwingshackl L, Hoffmann G, Lampousi AM, et al. Food groups and risk of type 2 diabetes mellitus: a systematic review and meta‑analysis of prospective studies. Eur J Epidemiol. 2017;32(5):363–75.
43. Schwingshackl L, Schwedhelm C, Hoffmann G, et al. Food groups and risk of hypertension: A systematic review and dose‑response meta‑analysis of prospective studies. Adv Nutr. 2017;8(6):793–803.
44. Lotan Y, Buendia Jiménez I, Lenoir‑Wijnkoop I, et al. Primary prevention of nephrolithiasis is cost‑effective for a national healthcare system. BJU Int [Internet]. 2012 Dec;110(11c):E1060–7.