Key Tips on Hydration (Volume 3)Hydration needs for different climatic situationsIndex• Key Tips on Hydration for holidays.• Key Tips on Hydration for winter.• Key Tips on Hydration for hot weather.• Key Tips on Hydration for variety.
SUMMER HOLIDAYSKEY TIPSON HYDRATIONDon’t forget toconsider yourhydration needs.In a temperate climate about 2-3 L of wateris lost from our bodies each day, mainly asurine but also as sweat, expired breath, andfaeces.The total amount of water lost will depend on several factors, such as gender, body size, the level ofphysical activity and the amount and type of clothing worn. Environmentalconditionsoftemperatureand humidity will also have an impact on water loss.Sweating or perspiring is a skin-cooling mechanism that uses a great deal of water. Water diffusionthrough the skin accounts for about 0.45 L per day. However, environmental temperature and humidity,the presence of air currents, the amount of clothing worn and the level of physical activity are allfactors that will influence the actual amount of water lost1.For Heathcare Professionaldistribution onlyAre you aboutto go awayon holiday?Sweat losses will be higher when exposed to high temperatures, such as inthe summer or in any other hot environment, and these must be replaced.Hydration requirements need to be considered both, duringtravelling and in the holidaydestination.When taking a planeThe body tends to dehydrate while travelling on aeroplanes because air in the cabin is dryer (10-20%humidity) than a typical, comfortable indoor environment (30-60% humidity) and this is due to the airconditioning. Under these conditions skin dehydration symptoms can be observed (parched lips, dryeyes, itchy eyes, etc.) and increased amounts of water are lost through the breath. Mild dehydrationoccurring during long flights is one of the causes of an increased blood viscosity, which in turn mayincrease the risk of deep vein thrombosis2.When travelling by plane, hydration levels can be maintained by drinking an additional 250 mL ofwater per hour over your regular hydration needs.
KEY TIPS ON HYDRATIONYou can find information about how to recognize signs and symptoms of mild dehydration, andpractical advice about hydration during hot weather in our series of educational materials:Key Tips on Hydration: recognizing signs and symptoms of mild dehydration.www.europeanhydrationinstitute.org/files/EHI_Key_Tips_on_Hydration_Signs_and_symptoms_of_mild_dehydration.pdfKey Tips on Hydration: hot weatherhttp://www.europeanhydrationinstitute.org/files/EHI_Key_Tips_on_Hydration_Hot_Weather.pdf1. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSA Journal 2010;8(3):1459. Available online: www.efsa.europa.eu/en/efsajournal/pub/1459.htm 2. Hamada K, Doi T, Sakura M, Matsumoto K, Yanagisawa K, SuzukiT, et al. Effects of Hydration on Fluid Balance and Lower-Extremity Blood Viscosity During Long Airplane Flights. JAMA 2002; 287: 844-5. 3. Manz F,Johner SA, Wentz A, Boeing H, Remer T. Water balance throughout the adult lifespan in a German population. Br J Nutr 2012; 107(11):1673-81.70-80%from beverages (all types,not just plain water)1,320-30%typically comes from food andIt is calculated that ofthe total water needed…However, this may vary greatlydepending of the diet that anindividual chooses.1,3If you travel by carDriving in a hot car can lead to sweating with large losses of water and electrolytes. Even in anair conditioned car, water losses can be high on a long drive. Maintaining adequate hydrationwhile driving is of great importance, because even with mild dehydration (loss of about1% ofbody weight) reductions in physical and cognitive performance and in thermoregulation andcardiovascular function can occur. With fluid deficits of 4%, more severe performance decrementsare observed as well as difficulties in concentration, headaches, irritability and sleepiness1.Frequent drinks of non-alcoholic beverages during a long automobile trip may help to reduce roadfatigue. The dryness caused by an air conditioning unit can be avoided by increasing the air’s moisturelevels and by hydrating the skin.Have you checked the weather forecast at your destination?It is important to keep an eye on the weather forecast, temperature and humidity in the city or regionyou are visiting in order to adjust hydration levels accordingly.SOME PRACTICAL ADVICE:• Get to know your usual hydration needs and adjust them to the place you are visiting and the levelof activity you are planning.• The hotter and more humid the weather is, and the higher the level of activity, the more water willbe needed. You can meet your hydration needs with a whole range of beverages and with food richin water. Take into account that:
Hydration in winterKEY TIPSON HYDRATION For HeaLthcare Professionaldistribution onlyIn cold climates, body fluid losses can be as high as those in hot climates because of high rates ofenergy expenditure, use of heavy clothing and increased losses in urine1,2.Under normal conditions, urine and sweat are the main methods of water loss, but we also losewater via the lungs and faeces. These losses vary widely depending on fluid intake, diet, activity level,temperature and clothing2,3.Respiratory lossesDaily respiratory water loss is normally about 250 to 350 mL/day for sedentary people, but canincrease to 500-600 mL/day for active people4. The actual amount lost is influenced greatly byenvironmental conditions (air temperature, humidity and wind speed) and the level of physical activity3.Winter activities such as skiing, snowboarding and ice-skating can therefore greatly increasewater loss, as can working or playing outdoors in the winter: Breathing cold, dry air can increase respiratory water loss by approximately 5 mL/hour1, so thiseffect in itself is generally rather small for short exposures, but becomes meaningful whenliving in very cold climates and exposed to these conditions for 24 hours per day. Stressful physical exercise in cold weather can increase this loss to approximately 15 to 45mL/hour1because of the increased rate and depth of breathing.Urine lossesAs the body gets colder, water loss as urine increases due to a higher urination rate, a physiologicalresponse known as cold-induced diuresis, which produces urine of low specific gravity* 2,3.* Specific gravity of urine is a measure of the concentration of solutes excreted.INTAKE OUTPUTMetabolism400 mLFood500 mLDrinking1500 mLBreathing400 mLSkin400 mLUrine1500 mLFaeces100 mLExample of normal water balanceIn cold weather conditions,additional water losses occur asa result of increased urine andrespiratory water losses. Somewater is also lost through theskin as a result of heavy clothingand because sweat evaporatesquickly in cold, dry air.
KEY TIPS ON HYDRATION70-80%from beverages(all types, not just plain water)2,720-30% typically comesfrom foodand aboutHowever, this may vary greatlydepending of the diet that anindividual chooses.2,7Practical tips to stay hydrated during the winter Drink plenty of fluids, especially when exercising or working outdoors. Drink regularly even when not thirsty as the sensation of thirst is reduced in coldweather, and this can lead to dehydration5. Meals play an important role in helping to stimulate the thirst response causing theintake of additional fluids and restoration of fluid balance6. Meals also provide water; it is calculated that of the total water needed: Avoid excessive amounts of heavy clothing as it can cause significant sweating andwater and mineral salt loss. Although urine colour is generally a useful index of hydration status*, this may notbe true in the cold when the cold stress may lead to an increased rate of productionof diluted urine. The skin should also be cared for, as cold, dry air outdoors and indoor heatingcontribute to the removal of water from the skin, causing dry, cracked skin9.* See our educational material about how to measure hydration status at: www.europeanhydrationinstitute.org/educational_materials.html1. Freund BJ, Young AJ. 1996. In: Buskirk ER, Puhl SM, eds. Body Fluid Balance: Exercise and Sport. Boca Raton, FL: CRC Press. Pp. 159–181. 2. EFSAPanel on Dietetic Products, Nutrition, and Allergies (NDA). EFSA Journal 2010; 8(3):1459. Available at: www.efsa.europa.eu/en/efsajournal/pub/1459.htm 3. Panel on Dietary Reference Intakes for Electrolytes and Water (2005) Dietary reference intakes for water, potassium, sodium, chloride, andsulphate. National Academy Press: Washington DC. 4. Hoyt RW, Honig A. 1996. In: Buskirk ER, Puhl SM, eds. Body Fluid Balance: Exercise and Sport.Boca Raton, FL: CRC Press. Pp. 183-196. 5. National Research Council. Nutritional Needs in Cold and High-Altitude Environments: Applications forMilitary Personnel in Field Operations. Washington, DC: The National Academies Press, 1996. p. 170. 6. Maughan RJ, Leiper JB, Shirreffs SM. EurJ Appl Physiol Occup Physiol 1996;73(3–4):317-325. 7. Manz F, Johner SA, Wentz A, et al. Br J Nutr 2012; 107(11):1673-81. 8. Kolasa KM, Lackey CJ,Grandjean AC. Nutrition Today 2009;44:190-201. 9. Weber TM, Kausch M, Rippke F, et al. J Clin Aesthet Dermatol. 2012;5(8):29-39.
IN HOT WEATHERKEY TIPSON HYDRATIONSymptoms ofdehydration• MILD (around 1% of body weight). Symptoms may include: thirst, headache,weakness, dizziness, feeling tired andlethargic.• MODERATE (around 4% of body weight).Symptoms may include: Dry mouth, little orno urine, sluggishness, rapid heartbeat, lackof skin elasticity.• SEVERE (10% or more of body weight).Symptoms may include: Extreme thirst, nourine, rapid breathing, altered mental state,cold, clammy skin. Severe dehydration is a life-threateningmedical emergency and can be fatal.For HeaLthcare Professionaldistribution onlyHot weather conditionscan increase the body temperature resulting in serious stressesfor the body, placing it in greater danger of injury (heat cramps, heat exhaustion or heat stroke) orin extreme conditions, death.Sweating or perspiration is one of the mechanisms used by the body to cool itself inconditions of heat. This water loss is often accompanied by disturbances in the body’s mineral saltor electrolyte balance – especially disturbances in the concentrations of sodium and potassium.That’s why, besides usual water losses (2-3 L/day), water (and salt) lost as additional sweat mustalso be replaced when we are exposed to high temperatures.As environmental temperature rises, the risk of dehydration increases.Dehydration symptoms should be carefully monitored, especially in those people particularlysusceptible to heat reactions:- elderly people,- young children,- chronic invalids and those taking certain medications which increase the risk of dehydration, suchas diuretics,- people with weight or alcohol problems.
KEY TIPS ON HYDRATIONTo know more about the sources of water, please visit us at:http://www.europeanhydrationinstitute.org/nutrition_and_beverages.html1. Manz F, Johner SA, Wentz A, Boeing H, Remer T. Water balance throughout the adult lifespan in a German population. Br J Nutr 2011; 1-9 [Epubahead of print] 2. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSAJournal 2010; 8(3):1459. Available online: http://www.efsa.europa.eu/en/efsajournal/pub/1459.htmThe Panel on Dietetic Products, Nutrition and Allergies from the European Food Safety Authority (EFSA)2issued referenceintakes for water in 2010. These are defined as total water intake, which is water from beverages (including drinking water)and from food moisture. It is normally assumed that the contribution of food to total dietary water intake is 20 to 30%, while 70to 80% is provided by beverages. This relationship is not fixed and depends on the type of beverage and on the choice of foods.70-80%from beverages (all types,not just plain water)1,220-30%typically comes from food andIt is calculated that ofthe total water consumed…However, this may vary greatlydepending of the diet that anindividual chooses.1,2Some tips to ensure proper hydration of the body in hot weather.Reduce water loss:• In Summer, avoid going out in the hottest temperatures (11 to 16 h in Europe).• If outside during these times, wear a hat, and light clothes.• Reduce intensity and duration of exercise.• Avoid badly ventilated places, close the shutters during the day and do not open the windowsbefore the outside temperature has dropped (at night).• Ask for advice about any medications you are taking, especially if they increase the risk ofdehydration.• Monitor your weight. In the short term (1-2 days), any weight that is gained or lost is probablywater.Learn to recognise signs of dehydration and heat stroke:• These are neither specific nor sensitive, but monitor headaches, fatigue, thirst.Increase fluid intake:• Ensure adequate water intake during the whole day, and pay special attention to the needs ofthe most susceptible people.• Drink regularly even when you are not thirsty.• Eat food which is rich in water and avoid excess alcohol.
HOW VARIETY CAN HELP HYDRATIONKEY TIPSON HYDRATION For HeaLthcare Professionaldistribution onlyGiven the particular importance of beverages in ensuringour hydration, it is important to know that:• Plain water is a significant source of liquid intake for most people, but many beverageslike juices, milk, soft drinks, coffee and tea are more than 85% water and are therefore animportant source of water.• In addition to thirst, habit is very important in determining what and when we drink.• Having available a variety of beverages may result in people drinking up to 50% more liquidsthan if only water was available, as shown in a study of fluid intake of runners on a treadmill.3• The pleasant taste of beverages is the reason why many people choose to drink beverageslike soft drinks, tea, milk, etc. instead of plain water.• All non-alcoholic beverages and some weak alcoholic beverages hydrate and contribute toan adequate hydration, including those containing caffeine such as coffee, tea and some softdrinks.• The role of variety in hydration has been recognised by International organisations suchas the International Life Sciences Institute (ILSI)4and the European Food Safety Authority(EFSA)2and it is particularly important for population groups that may be vulnerable todehydration including children and elderly people.• EFSA adequate intake advice for water relates to water from all sources in the diet (includingplain water, food and beverages).2Please see our website to know more about the contents of water of different foods and drinks:www.europeanhydrationinstitute.org/hydration_and_nutrition.html70-80%from beverages(all types, not just plain water)1,220 -30%typically comes from foodand aboutIt is calculated that of the total water consumed, aboutHowever, this may vary greatlydepending of the diet that an individualchooses.1,2
KEY TIPS ON HYDRATIONIncluding different beverages in the diet can also provide other benefits:For example:• Many beverages provide important nutrients such as vitamins, antioxidants and electrolytesthat contributes to our daily needs.• Fruit juices can contribute to the five portions of fruit and vegetables that we are recommendedto consume each day.• Sport drinks contain small amounts of sugar and electrolytes that help to reduce water, mineraland energy imbalance due to physical exertion.• Caffeinated drinks such as coffee can provide a stimulus when tired.Although a variety of beverages contributes to hydration, it is important to take into account thatunlike plain water, beverages often contain calories and therefore they contribute to the daily energyintake. The wide variety of low-calorie and no-calorie drinks available nowadays helps to reducethis contribution. Guideline Daily Amounts (GDAs) are available in most countries to help people tomake informed choices about the products they buy.A variety of sources,colours and tastes isimportant towardsachieving thenecessary liquidintake for optimalhydration and tomeeting nutritionalneeds.1. Manz F, Johner SA, Wentz A, Boeing H, Remer T. Water balance throughout the adult lifespan in a German population. Br J Nutr 2011;1-9 [Epub ahead of print] 2. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary referencevalues for water. EFSA Journal 2010; 8(3):1459. Available online: http://www.efsa.europa.eu/en/efsajournal/pub/1459.htm 3. López-Román J, Martínez Gonzálvez A, Luque A,Villegas García JA. Estudio comparativo de diferentes procedimientos de hidratación duranteun ejercicio de larga duración. Archivos de Medicina del Deporte 2008; 25(123): 435-441. 4. ILSI Scientific Consensus Statementregarding the Importance of Hydration and Total Water Intake for Health and Disease. J.Am Coll Nutr 2007; 26(S): 529-623.