Health Professional Corner Volume 1 http://www.europeanhydrationinstitute.org/

1.
Health Professional Corner (Volume 1)
Index
• Water content in food and beverages
• Exercising in the heat – effects on carbohydrate metabolism
• Hydration requirements in the elderly
• Hyponatraemia in marathon runners: Is it a real problem?

2. 2. EHI Update: May 2010
· HEALTH PROFESSIONALS CORNER
Water content in food
and beverages
Total daily water intake is the sum of water content coming from all types of
beverages and foods.
Many people underestimate the water content of food and beverages - below
there is a table showing the content of many common foods. foods.
Type of food Water content
Non-alcoholic beverages
Water, tea, coffee, light refreshments, sports drinks, soft
drinks, lemonade, vegetable juice
90% to 100%
Milk, fruit juice, juice beverages 85% to 90%
Alcoholic beverages
Beer and wine 85% to 95%
Distilled 60% to 70%
Soup
Consommé, onion, meat and vegetable, vegetables,
tomato, mushroom cream, Noodle with chicken,
vegetable concentrate, concentrated soups, mushrooms
cream (made with milk)
80% to 95%
Fruits and vegetables
Strawberry, melon, grapefruit, grape, peach, pear, orange,
apple, cucumber, lettuce, celery, tomato, pumpkin,
broccoli, onion, carrot
80% to 95%
Banana, potato, corn 70% to 80%
Dairy products
Fresh whole milk 87% to 90%
Yoghurt 75% to 85%
Ice creams 60% to 65%
Cheese 40% to 60%
Cereals
Rice (boiled) 65% to 70%
Pasta (spaghetti, macaroni, noodles) 75% to 85%*
Bread, cookies 30% to 40%
Breakfast cereals (ready to eat) 2% to 5%
Meat, Fish, Eggs
Fish and seafood 65% to 80%
Eggs (scrambled, fried, poached), omelette, egg substitute 65% to 75%
Beef, chicken, lamb, pig, veal 40% to 65%
Cured meat, bacon 15% to 40%
Source: Holland B. et al(1991). McCance and Widdowson’s The Composition of Foods. 5th ed.
The Royal Society of Chemistry, Cambridge.
Note that these values are approximations only and values will depend on source of the food, cooking method, etc.
For example pasta cooked “al dente” (Italian style) will have a slightly lower water content than shown here* and is
between 50 and 60%.
There are many good online databases that will give food composition values for a much wider range of foods
10
hydration
tips
1. Body water is essential for health and
well-being. Humans cannot survive
for long without water intake, but
neglecting other nutrients for weeks or
even months does not give rise to the
same challenges.
2. Humans are usually very good at
balancing fluid losses and fluid intake
in the medium to long term, but in the
short term intake and losses are often
not well matched.
3. Thirst may not always be a good guide
to body water needs.
4. Water is lost through sweat, urine,
breath, faeces and skin. Losses will
be greater with a high environmental
temperature, high altitude, or increased
levels of exercise. Gastrointestinal
diseases (vomiting, diarrhoea) also
increase water and salt losses.
5. Under normal conditions, the adequate
total daily water intake* from all
sources, including foods and drinks, is
about 2.5 L for adult males and 2.0 L
for adult females, but some individuals
will need more than this and some will
need less.
6. In hot climates, it is best to avoid
unnecessary exposure to the sun in the
middle of the day and afternoon. Intense
exercise is also best avoided at these
times.
7. Pregnant or breastfeeding women,
children and the elderly are more
susceptible to dehydration. Those
looking after children or the elderly
should ensure that they drink enough.
8. Foods with a high water content, such
as fruit, vegetables, soups, etc, can
make a significant contribution to daily
water intake.
9. Consumption of a wide variety of
drinks can help in achieving the
recommended total daily water intake.
10. Health professionals, dieticians and
nutritionists are the experts in helping
people understand how to maintain
optimum hydration levels.
*Total daily water intake is the sum of
water content coming from all types of
beverages and foods.
· HINTS & TIPS
www.europeanhydrationinstitute.org

3. 2. EHI Update: July 2010
· HEALTH PROFESSIONALS CORNER
Exercising in the Heat –
Effects on carbohydrate
metabolism
Prof. Andreas Niess
Elevated ambient temperatures can impair exercise performance, especially
in endurance sports.
An earlier onset of fatigue during exercise is typical of such conditions and
results primarily from a rise in body temperature and progressive dehydration.
In turn, these changes lead to functional consequences, which also affect
energy metabolism in the working muscle:
• Exercising at an identical work load in the heat leads to a faster depletion
of muscle carbohydrate (glycogen) stores. Carbohydrate can be used up to
25% faster compared to cool ambient temperatures.
• The underlying mechanisms for this phenomenon are not completely clear.
However, progressive dehydration and an increased blood flow to the skin to
facilitate heat dissipation during exercise may reduce the delivery of blood-
borne energy sources such as glucose and fat to the working muscle. Higher
levels of stress hormones, including adrenaline, may also be involved.
• Importantly, adaptation to heat improves performance under such conditions
and also lowers muscle glycogen use during exercise. In parallel, after heat
acclimatisation liver glycogen makes a greater contribution to energy supply
for the working muscles.
• In the heat, the use of exogenous carbohydrates in working muscle delivered
by a sports drink or other sources is reduced. Suppression of intestinal
absorption and carbohydrate delivery to working muscle are potential
causes for this finding.
• To help ensure adequate hydration, a drink with a low carbohydrate content
(approximately 50-60 g/litre) is recommended for use during exercise in the
heat.
• After exercise, in addition to attending to hydration needs, replenishment
of muscle glycogen stores by carbohydrate-rich fluids and foods is also of
importance if endurance-sports have been performed in the heat.
Keeping cool
without
becoming too
dehydrated
Prof. Patrick Ritz
Dailywaterlossviatheskin,therespiratory
tract, urine, sweat and faeces amounts to a
total of 2-3 l/day for an average individual.
These losses must be replaced to preserve
health and performance. The following
advice can help you to do this.
Tips
1.Learn to recognise signs of dehydration
and heat stroke.
These are neither specific nor sensitive:
they include low blood pressure, elevated
pulse and respiratory rates, headache,
weakness, dizziness, ‘‘heat sensations’’
on the head or neck, chills, ‘‘goose flesh’’,
nausea, vomiting, diarrhoea, irritability,
and decreased coordination. If rectal
temperature is > 40° Celsius, heat stroke
is likely. This is a medical emergency:
survival depends on the speed of the
treatment.
2.Monitor your weight.
In the short term (1-2 days), any weight
that is gained or lost is probably water.
Usual weight should be known and
monitored often, especially in the young
and the very old.
3.Pay attention to your lifestyle.
a.Reduce intensity and duration of exercise
when the heat stress index is high.
b.Avoid going out in the hottest
temperatures (11 to 16 hrs in Europe). If
necessary, wear a hat, and light clothes.
c.Choose where to stay. Avoid badly
ventilated places, close the shutters
during the day and do not open the
windows before the outside temperature
has dropped (at night).
d.In hot weather, ask for advice about
any medications you are taking.
Certain treatments increase the risk of
dehydration. These include diuretics,
but also treatments for Parkinson’s
disease and some antidepressants.
4.Increasefluidintakesothatbodyweight
is stable.
Ensure that the young and the very old
drink regularly even if they do not ask for
drinks. Eat lots of fruits and vegetables
which are rich in water and avoid excess
alcohol.
5.Encourage heat loss.
Take regular showers or a cool bath,
without drying yourself. Bathe frail people
with a wet sponge, many times a day.
· HINTS & TIPS
www.europeanhydrationinstitute.org

4. 2. EHI Update: October 2010
HEALTH PROFESSIONALS CORNER
Hydration Requirements
in the elderly
Prof. Lluis Serra-Majem
Adequate hydration in older adults is a common yet complex problem and the
solutionrequiresacomprehensiveapproach.Facility-wideinvolvementiscritical
for the success of a hydration programme. Dehydration is ranked as one of the
top ten reasons for Medicare hospitalizations. Increasing age is a major risk
factor for dehydration, and persons between 85 and 99 years are 6 times more
likely than young people to be hospitalized for dehydration. Chronic dehydration
constitutes a serious problem and is associated with an increased risk of falls,
urinary tract infections, dental disease, bronchopulmonary disorders, kidney
stones, cancer, constipation, and impaired cognitive function.
With age, the body loses its ability to detect thirst. Some elderly people also
suffer from poor memory, immobility, or illness - which can result in reduced
fluid intake. Moreover, most people beyond a certain age require a range of
medications,andsomeofthesecanobstructthethirstmechanism.Someelderly
individuals reduce liquid intake to avoid urinary incontinence, especially at night
or when away from home. Thus, many elderly drink insufficient quantities of
liquids, especially in hot climates/conditions. The recommendations for daily
intake of liquids do not fall with age in adults (2.5 L for men and 2 L for women).
In hot environments, it is recommended that intake of liquids be increased by
250 ml (1 cup) for each degree centigrade over 37ºC.
Symptoms of dehydration in the elderly can be nonspecific and their appearance
is often delayed. Thirst, dry skin and mucosa, decreased urine output and
constipation are the most frequently cited. In more severe cases, sudden weight
loss, dark concentrated urine, drowsiness, headaches, confused states and
extreme fatigue may occur.
Moderate temperatures, varying flavours and even colours can improve
palatability of beverages offered and can help facilitate adequate hydration in
the elderly. Strong alcoholic beverages may provoke dehydration and are not
recommended. Heavy meals should also be avoided as they increase the need
for liquids.
A hydration programme should include advice on drinking, offering fluids at
mealtime and in between meals, identifying signs and symptoms of dehydration,
and notifying the physician or nutritionist as appropriate. Healthcare staff should
be familiar with dietary changes common in elderly adults so that appropriate
hydration recommendations can be made.
Hydration
and healthy
aging
Dr. Andrea Poli
Older people are a diverse group
with individual needs and desires. In
general their water requirements are
very similar to those of younger adults,
but age-related changes can lead to
an increased risk of dehydration with
consequent effects on health and
wellness. For example:
• Thirst, the body’s natural response
to dehydration, has been shown to be
impaired in some elderly people.
• Renal concentrating capacity
generally declines, leading to an
increased loss of water via urine.
• Diminished appetite and poor food
choices may lead to a reduction of
fluid intake from food (about one fifth
of daily water intake normally comes
from food).
• Reduced mobility may discourage
intake by making it more difficult to
reach sources of fluids.
Carers have a vital role in helping older,
more dependent individuals to maintain
healthy hydration levels and should be
aware of the issues listed above.
They can do this by ensuring that:
• Fluids are readily available and
physically accessible both day and
night as well as with meals.
• They are aware of the individual’s
need for fluid and encourage them to
drink.
• A variety of drinks, possibly with
different tastes, is on offer to
encourage consumption.
• The environment is not too warm and
that extra fluids are provided on hot
days.
Many types of foods contain a
substantial amount of water. If an older
person finds it difficult to increase the
amount of fluid drunk, increasing the
intake of foods, such as soups or fruit
and vegetables, which typically contain
80-90 per cent water, can help to
maintain an adequate water intake as
well as being good sources of essential
nutrients.
HINTS & TIPS
www.europeanhydrationinstitute.org

5. For many years, the advice to those
taking part in endurance activities
was to be sure to drink enough
to prevent dehydration. Because
this advice was initially developed
for elite athletes in sports such as
marathon running, the advice was
often to drink as much as possible.
This was based on the fact that the
elite runner taking just a little over
2 hours to complete the race in
men and a bit less than 2½ hours
in women, were working close to
their maximum and had limited
opportunities for drinking. Until
the advent of popular marathons,
there were also rather few drinking
stations – nothing before 10 miles
(16 km) and then every 5 miles (8 km)
thereafter. In practice, drinking as
much as possible usually translated
into drinking not very much at all.
Today, most major marathons have
drinks stations every mile (1.6 km)
and the average finishing time in
many big city races is about 4½ hours
for men and 5 hours for women. At
these much slower speeds, sweat
rates will be much lower, but the
opportunities for drinking at every
station are far greater. It is not
surprising, therefore, that the slower
runner who follows the advice to
drink as much as possible will drink
far more than is needed to balance
sweat losses.
Drinking excessive amounts will
lead to a dilution of the sodium
concentration in the blood plasma –
a condition known as hyponatraemia.
Mild hyponatraemia – or even a more
markedhyponatraemiathatdevelops
very slowly - is fairly harmless, but
a large and rapid fall in the plasma
sodium level will lead to an influx of
water into the body’s cells to balance
the osmotic forces. Increasing the
water content of the brain can lead
to an increase pressure within the
skull: at its most serious, this can
lead to seizures and coma and, very
occasionally, it can prove fatal.
It is important to drink enough,
but common sense would suggest
that high rates of fluid intake are
not needed by slow runners in cool
weather. This message should be
communicated by race organisers to
all participants.
2. EHI Update: December 2010
HEALTH PROFESSIONALS CORNER
Hyponatraemia in
marathon runners:
Is it a real problem?
Prof. Ron Maughan
Hydration
durinG
exercise
A recent publication from the American
College of Sports Medicine* (ACSM),
provides tools to create customized
fluid replacement guidelines and
recommendations for fluid ingestion
and the prevention of heat injury during
exercise. The following are some of
ACSM’s main recommendations:
· Fluids before, during and after
exercise are an important part of
regulating body temperature and
replacing body fluids lost through
sweat. Thirst alone is not the best
indicator of dehydration or the body’s
fluid needs.
· Sweat rates and electrolyte
losses vary based on individual
characteristics including, but not
limited to, body weight, genetic
predisposition, and metabolism. Also,
air temperature, humidity, clothing,
and the type of activity are factors
in determining sweat losses and
rehydration needs.
· Before exercise fluid intake is needed
to start the physical activity at
“normal” body water and electrolyte
levels and this should be ingested
several hours before exercise. ACSM
recommends beverages or food with
sodium to help stimulate thirst or
retain fluids.
· During exercise fluid replacement
is needed to prevent excessive
dehydration (> 2% body weight
reductions from baseline body
weight) and to avoid excessive
changes in electrolyte balance to
avert compromised performance.
The amount and rate will depend
on the individual and the activity
(accounting for opportunity to drink).
The guidelines note that consuming
beverages containing electrolytes and
carbohydrates often provides more
benefits than consuming water alone.
· After exercise fluid and electrolyte
losses should be replaced depending
on the magnitude of fluid-electrolyte
deficits.
Source: Medicine & Science in Sports & Exercise
2007; 39(2): 377-390.
* The American College of Sports and Medicine is
the largest sports medicine and exercise science
organization in the world. More than 20,000
international, national, and regional members
are dedicated to advancing and integrating
scientific research to provide educational and
practical applications of exercise science and
sports medicine.
HINTS & TIPS
www.europeanhydrationinstitute.org

6.
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