HYDRATION:CONSUMER INFORMATION AND

MISINFORMATION

Catherine Collins RD FBDA

Principal Dietitian

St Georges Hospital London

Water ….

� Is both a food and a nutrient

� Acts as a solvent in which inorganic salts, organic compounds and dissolved gases interact

� Participates in metabolic reactions

� Stabilises cell membranes

� Maintains structure of macromolecules

� Transports nutrients

� Key agent in thermoregulation

Where is it?

70kg man

10.8 litres interstitial fluid

3.2 litres plasma

14 litres extracellular water

42 litres total body water

28 litres intracellular water

5-10% of water turnover daily

Total body water is tightly regulated within ±0.2%

of body weight each day

Sawka M et al; Nutr Rev 2005

Bossingham M et al; AJCN 2005

Water composition of tissues and organs(% by weight)

% water by weight:

blood 83%heart 79%muscle 76%skin 72%liver 68%bone 22%adipose tissue 10%

Body has no provision for water storageWater must be replenished by regular intakeA wide range of fluid intake will cause neither dehydration or over-hydration in an individual

“humans cannot survive for more than a few days

without ingesting water in excess of solutes”Adolph EF: Physiology of Man in the Desert. New York, Interscience Publishing Co., 1947

“Humans can only survive for a few days without water”discovery.com/survival/medical-conditions/dehydration.html

Terri Schiavo

Bulimic. Gastrostomy fed for 15 years for PVS

Feeding tube removed under Florida court order after

widespread media campaign of husband v parents

Survived a further 13 days without fluidsDied March 2005

Dehydration: how soon a risk?

Quill, T. NEJM 352:1630 1995

Insensible losses

Urine output

Faecal losses

Environment temp

‘Preformed’ water:

Fluid as pure water

Fluid in beverages

Fluid from food

Oxidation of macronutrients

Obligate losses:

Metabolic water:

Breakdown of body tissue

IN OUT

Pyrexia

Blood volume

Humidity

Influenced by:

FLUID BALANCE

Plasma osmolaritydefines fluid status

insensible losses

gastric aspirates

drain/ wound losses

haemofilter

3rd space oedema

iv infusions x 10

enteral feed

Intensive care

clinical biochemistry

hourly fluid balance charts

central venous pressure

clinical observation

Proxy markers of hydration:

� Urine volume:

� There are limits to concentrating and diluting effect of the kidney:

� Maximum urine osmolarity 900-1400 mOsm/l

� Minimum urine omolarity 50mOsm/l

� Concentrating ability of the kidney by 3.4mOsm/ l per year after the age of 20

(Manz and Wentz, 2003)

� affected by insensible losses

� Urine colour:

� The darker the urine, the more concentrated it is

� can be affected by non-hydrating factors:

� vitamin B supplements can turn urine bright yellow

� anthocyanins in blackberries, beetroot can turn urine brown/purple

� Body weight

Thirst:nature’s early warning, not sign of dehydration doom

� stimulated by:

� an increase in plasma osmolality

� a decrease in plasma volume

� a decrease in blood pressure

� vasopressin is responsible for controlling water balance on a daily basis

� net fluid loss of as little as 1% of body weight will increase plasma osmolality

� thirst begins when the concentration of blood has risen by < 2%

� a moderate fluid deficit of 7-10% is intolerable in cognisant individuals

� water deficit of 20% is life-threatening

Bossingham M et al; AJCN 2005Heitz and Horne, 2001

Survey of 1000 office workers:how can you tell if you’re dehydrated?

� Feel thirsty 83%

� Headache 75%

� Dry mouth 60%

� Dark coloured urine 60%

� Fatigue or weakness 44%

� Dry Skin 39%

� Irritable 21%

� Hungry 21%

� Hangover 15%

Keep It ‘ Light’campaign

� 51% of office workers drink between 1-4 cups of tea a day

� 52% drank between 1-4 cups of coffee a day

� 79% drank no carbonated drinks at all

� 95% drank no enriched waters

� Double the amount of “Younger” people are drinking vitamin/juicy water compared to “older”

people

� 8% of the 16–24 and 25-34 age ranges drank these

� only 4.1% of the 45+ age range drank these

372283Milk, all types

1134523Tea, coffee,

water

287287Soft drinks

low calorie

259368Soft drinks

not low calorie

134160Fruit juice

All: 19-64y

mean intake

All: 11-18y

mean intake

NDNS 2008-9: intake of drinks, grams per day

9790

3560

5583

4248

19-64y11-18y

% consumers

15,000,000 man hours to build: 1,875,000 days

1,875,000 x 4 cups of tea = 7.5m

20% of builders state they don’t drink tea at work

Total: 6 million cups of tea

How many cups of tea to build St Pancras International station?

68% found tea to have relaxing and stress relieving properties.

81% polled revealed the daily tea ritual helped them bond with fellow workers

70% believe tea breaks provide the opportunity to make important decisions

about work and keeps them focused on the job in hand.

online poll with the Federation of Master Builders, 2007

?

“In essence the ubiquitous bottles of water kept at hand by countless millions have begun to resemble the security blankets of childhood”

The rise and fall of bottled water, 2007 report

“We find that the main reason consumers are drinking so much water is that it seems to alleviate stresses and tensions causedby a lack of ritual in the workplace and in home life…..”

The ‘8 glasses of water’ myth

8 x 150ml = 1200ml 8 x 568ml = 4544ml

US National Academy of Sciences Food and Nutrition Board RDA 1945 edition:

“A suitable allowance of water for adults is 2.5 liters daily in most instances. An ordinary standard for diverse people is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods”

How much water a day?

� 70.4% quoted 6-8 glasses a day (1.5 – 2 litres)

� 78% of females and 58% of males chose this

response

� 14.8% stated 4-5 glasses a day

� 1.8% thought 2-3 glasses

� 0.6% thought 1 glass of water a day

� 7.1% had no idea

% Water by weight in foods

Canteloupe melon

Carrot

Chicken

Cheese

Crackers

90

7

36

67

88% water by weight:

80% of fluid comes

from fluids

20% from foods

Mouthfeel mistakes

� Many drinks are discounted by consumers as non-hydrating, even when evidence proves they are

� This can be due to mouthfeel factors:

� Tea and wine astringency: the drying sensation in the mouth caused by unoxidised catechin polyphenols

� Adhesion of substances to oral mucosa, stimulating feeling of secretions: eg fat globules feel like mucus. Research proves that milk does not increase nasal congestion or nasal secretion volume.

Pinnock et al; Am Rev Resp Dis 1990

Misconception: all fluids are hydrating

� Plain water v diet drinks: no difference in hydrating statusGrandjean AC et al. J Am Coll Nutr. 2003

� 18 healthy males� crossover study� Combination of four different beverages (caffeinated/

caffeine free; energy drinks/ plain drinks) did not differ in effects on hydration

Grandjean AC et al. J Am Coll Nutr. 2000

CONCLUSION:� No significant difference between the regimens on indicators

of hydration status� The source of water doesn’t matter when the outcome is

hydration� the popular notion that caffeinated beverages cause

dehydration is a myth

Functional fluids:

� Water

� Flavoured or enriched water

� Soup

� Juice

� Milk

� Plant infusions – tea, coffee, herbal teas

� Alcohol

� Probiotic ‘shot’ drinks

� Cholesterol lowering drinks

� Health-promoting juices

Functional drinks:don’t live up to the hype

claims included:

being able to reduce atherosclerosis; reduce

blood flow/pressure; slow the onset of

prostate cancer; improve erectile function;

improve circulation; reduce cholesterol

Advertising support information:

results of four tests of antioxidant potency (TEAC, ORAC, DPPH, and FRAP)

Seeram et al; J Agric Food Chem 2008

Seeram et al; AJCN 1996

Pomegranate juice:

ellagitannins and anthocyanins

Tea:

theaflavones, catechins,

and phenolic acids

Warden et al; J Nutr 2001

Plasma antioxidant concentration over time

Functional fruit drinks: style over substance?

£1.39 85p+9p = 94p

these 10 +vitamin Dvitamin K

biotiniron

magnesiumzinc

iodinecopper

chromiummanganese

selenium

beta-carotenevitamin E vitamin Cvitamin B6vitamin B12niacin folic acidpantothenic acidcalciumpotassium

Worth overhydrating?

it is “difficult to believe that evolution left us

with a chronic water

deficit that needs to be compensated by

forcing a high fluid intake."

Valtin, H. Am J Physiol 2002

Risk of water loading: fitness� 25yo male admitted with GCS 5

via A+E

� Found collapsed at home

� Na 120 mmol/l (NR 135-145) on admission

� Urinalysis negative for drugs

� Had joined a gym to tone up/ lose weight two months earlier

� Fitness instructor had advised him to drink 4-6 litres of water a day and avoid ‘processed foods’

� Adopted low energy diet with moderate-to-low sodium content

� Took 3 days to restore plasma sodium safely

� Naturally woke on day 2

� Discharged home @ day 6

Risk of water loading: weight loss

Dawn Page, 54 year old mother of two

in 2008 awarded £800,000 in damages at the High Court after nutritional therapist recommended radical detox diet that left her brain damaged and epileptic

Warning signs of water intoxication were present and ignored by therapist

Therapist still practices, promoting ‘healthy hydration diets’

Scientific Consensus Statement on Hydration and

Health

Water is essential for life.

Foods and beverages contribute varying amounts of water in the diet.

Consuming a variety of non-caffeinated and caffeinated beverages, including water, milk, tea, coffee, juice, soft drinks and sports drinks can contribute to meeting the body’s water requirement.

Foods, including certain fruits, vegetables, soups and dairy products, can also contribute to meet the body’s water requirement.

Appropriate beverage and food choices for an individual may vary on the basis of energy, nutrient and water needs, as well as consumer preference

J Am Coll Nutr 2007

“ I am not a heavy drinker. I can sometimes go for hours

without touching a drop”

Noel Coward 1899-1973