© food – a fact of life 2010 hydration and health british nutrition foundation

© Food – a fact of life 2010

Hydration and health

British Nutrition Foundation


Hydration and health review

www.nutrition.org.uk/nutritioninthenews/hydration/

http://onlinelibrary.wiley.com/doi/10.1111/j.1467-3010.2009.01795.x/abstract

Benelam B and Wyness L (2010) Hydration and health Nutrition Bulletin 35 (1):3-25.


Healthy hydration

Water is essential for life.

The body is nearly two-thirds water.

Poor fluid intake can lead to dehydration.

All drinks count to fluid intake except stronger alcoholic drinks such as spirits and wine.

Water is also provided from food (about 20%).


How much are we drinking?

• Data on current water consumption in the British population are not available.

• Most recent National Dietary and Nutrition Survey (2000/01) estimated average fluid intake from drinks:

British men: 1988ml/day.

British women: 1585ml/day.


How much water does a person need?

The amount needed depends on:

• age;• climate;• physical activity.

It is generally accepted to drink around 1.2 litres

(6-8 glasses) per day.

This is on top of the water provided by food.


Dehydration

Being dehydrated can affect physical performance and cognitive ability (e.g. concentration and alertness).

Even slight dehydration (2%) can affect physical performance by 20% - this is not enough to feel thirsty.

By the time you feel thirsty you are already dehydrated.


Signs of dehydration

• feeling thirsty;

• having a headache;

• passing dark-coloured urine;

• feeling sleepy;

• being unable to concentrate.


Excess intake

Drinking excessive amount of fluids is not helpful to health and wellbeing, and in rare cases may be dangerous, leading to low levels of solutes in blood.

An example is hyponatraemia, which means low levels of sodium in the blood.

Signs of excessive intake are passing urine frequently and urine that is very pale in colour.


Urine test

The simplest way to tell if you are drinking enough is to check the colour of your urine.

If your urine is very dark you need to drink more fluids. Once it is pale, you are well hydrated again.


What should I drink?

When choosing drinks be aware of their energy content and other nutrients they may provide.

Choose drinks that will complement your diet.


Water

Delivers fluid without adding energy or potentially damaging teeth.

Does not contribute to energy intake.


Tea and coffee

Delivers water.

Moderate intakes of caffeine do not affect hydration.

Pregnant women are advised to consume no more than 200mg caffeine a day.

This is equivalent to 2 mugs of instant coffee or 3 cups of tea.


Provides protein, calcium and B vitamins.

Wholemilk contains saturated fat, it is advisable for adults to choose lower fat milks: semi-skimmed (2% fat), 1% or skimmed (less than 0.1% fat).

For children aged 1 to 2 years, wholemilk is recommended.

From 2 years onwards, semi-skimmed milk can be introduced.

1% or skimmed milks are not suitable for children until they are at least 5 years old.

Milk


Fruit juices and smoothies

Provide vitamins and minerals and natural plant substances.

Smoothies may contain puréed fruit, which adds fibre.

Juices (150ml) count towards one portion of 5 A DAY.

Smoothies (150ml juice and 80g crushed fruit)

count as two portions.

Sugars and acidity can be harmful to teeth.


Soft drinks

Provide water and sugar, which consumed in between meals, can be harmful to teeth.

Diet drihnks or sugar free versions may be a better choice.

Some people may wish to avoid artificial sweeteners.


What is the most popular drink in the UK?

Tea ...

Coffee …

Tap water …

Bottle water …

Soft drinks …

Fruit juice …

Alcoholic drinks …


What is the most popular drink in the UK?

Tea ...

Coffee …

Tap water …

Bottle water …

Soft drinks …

Fruit juice …

Alcoholic drinks …

536 ml/person/day

744 ml/person/day

333 ml/person/day

229 ml/person/day

211 ml ‘regular’ & 240ml low calorie/person/day

106 ml/person/day

425 ml/person/day

536 ml/person/day

744 ml/person/day

333 ml/person/day

229 ml/person/day

211 ml ‘regular’ & 240ml low calorie/person/day

106 ml/person/day


Alcohol

Weak alcoholic drinks (e.g. a shandy) contribute to fluid intake.

Stronger alcoholic drinks cause diuresis.

Alcohol recommendations:

Men - no more than 3-4 units per day.

Women - no more than 2-3 units per day.

Over consumption of alcohol, or binge drinking, should be avoided.


Units of alcohol

One unit of alcohol is:

• half a pint of standard strength (3 to 5% ABV) beer, lager or cider;

• a pub measure of spirit;

• half a glass of wine;

• two thirds of an Alcopops.


The effect of alcohol on water balance

Drink Serving Loss of water in urine (ml)

Net gain of water (ml)

Beer, larger and cider

568ml (1 pint) 170 398

Alcopops 330ml (1 bottle)

165 165

Spirits 25ml (small)

50ml (double)

100

140

-75

-105

Wine and champagne

175ml (standard)

210 -35


Contribution from food

Water is also provided from food (about 20%).

The amount of water in food varies from less than 10% in savoury snacks, less than 40% in cereal products to 80% or more in some fruit and vegetables.

Foods, such as soups, stews, yogurts have a high water content.


Some people need to drink more

•Children

•Lactating women

•Older adults


Physical activity

Even slight dehydration has been shown to affect sporting performance, so drink before, during and after you train or play a match.

Being dehydrated may mean that:

• running pace is slower;

• unable to cover as much distance;

• reaction time is slower;

• experience lack of power.


To keep hydrated:• drink lots before exercise;• don’t wait until you feel thirsty;• drink small, regular sips of water during exercise;• drink plenty when you have finished.

The fluid needed for activity is in addition to the 6 to 8 glasses or 1.2 litres needed every day.

It is also important to drink more when the weather is hot.

Keeping hydrated during exercise


Sports drinks

Sports drinks are designed to provide water and carbohydrate.

Some types are very quickly absorbed.

They can help you recover quickly after a hard match or training session.


Sports drinks

It is easy to make your own sports drinks at home and cheaper too!

Per 100ml water:

5-8g glucose powder.

0.5g salt.

Any sugar free flavouring.


Drinking schedule

A large glass one hour before you start.

A smaller glass 15 minutes before start.

Small sips during the event.

A glass at half time.

A large glass immediately afterwards.


Healthy hydration guide

www.nutrition.org.uk/nutritioninthenews/hydration/healthy-hydration-guide


Getting the balance right:

every day examples

www.nutrition.org.uk/nutritioninthenews/hydration/getting-the-balance-right-

everyday-examples


Are you drinking plenty? poster


For more information visit

www.nutrition.org.uk

www.foodafactoflife.org.uk

© food – a fact of life 2010 hydration and health british nutrition foundation

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