Water: The essential ingredient for success?
By: Dr Owen Bain
Tags: Water

Water makes up 60% of the body and 75% of the brain. To say it is essential is an understatement; in fact just 3 days without water can be fatal.

Dehydration can impact five aspects of your mental performance:

1. Decreased reaction time

2. Decreased short term memory

3. Reduced attention span

4. Reduced accuracy in complex tasks

5. Increased fatigue

If you are not getting enough, it could be impacting on your career.

Small habits

As I have discussed before creating something you can stick to is the key to success. Many sources recommend having up to 8 glasses of water a day. This is a myth dating back to a US recommendation in 1945! Not only is this far too much for most people, but is a difficult habit to keep.

Try instead

1. One glass of water, as soon as you wake up

2. Eat one more portion of fruit and vegetables a day

3. One glass of water before you go to bed

4. Drink water when thirsty (sounds simple, but many reach for sugary drinks instead)

5. If you don’t like ‘plain’ water, have a tea or coffee

““Knowing is not enough; we must apply. Willing is not enough; we must do — Goethe”

Remember water doesn’t just come from the tap. Meat is 50–70% water while fruit & vegetables can be 75–96% water.

Science of dehydration

Dehydration at a 2% body mass loss can impact your brain, and even 1% loss can cause your performance to decrease.

Water is required for the brain’s production of neurotransmitters and hormones. A study from Kings College London showed by MRI that dehydration increases ventricular expansion and causes inefficient use of brain metabolic activity after dehydration.

Other research has identified that the effect of water consumption is dependent on the subject’s thirst and the positive effects result from an ‘attenuation of the central processing resources consumed by the subjective sensation of thirst that otherwise impair the execution of speeded cognitive processes’. Translated into English: you can’t get on with the task at hand, as all your brain is telling you to do is ‘find and drink some water’!

Not all studies have shown a beneficial impact on cognition. This study showed no effects of dehydration in healthy subjects on performance of a number of cognitive tasks. However, they observed that dehydration caused changes in subjective ratings, such as increased tiredness, and higher levels of perceived effort and concentration.

Myth busting

Caffeine is a diuretic and will dehydrate you? Wrong. A team from the University of Birmingham studies took 50 coffee drinkers and had half of them drink 4 cups of coffee, and the other half the equivalent of water. Their results showed that no difference of total body water or urine volume (collected up to 24 hours) was found between the two groups. Suggesting coffee contributes to your daily fluid intake.

Can you drink too much?

As with everything in life there is a consequence of having too much. If you drink too much water you can suffer from what is known as hyponatremia. To put it simply, this is when the amount of water in the blood drowns out the sodium. This is commonly found in long distance runners who try and overcompensate by drinking too much water. It can cause confusion and headaches. However, there is little evidence to show the impact of this on your cognitive performance.

Summary

Water is vital for our brains to function, and to enhance productivity. However, as water is available in most food produce, an optimal amount is much less than the ‘8 glasses a day’ dogma.

Alleviating thirst is a key factor to reducing fatigue to maximise your mental performance.

Drink smarter. Perform Smarter

Owen

References

Cian C, Koulmann N, et al Influences of variations in body hydration on cognitive function: Effect of hyperhydration, heat stress, and exercise-­induced dehydration. Journal of Psychophysiology. 2000;14(1):29–3

Edmonds, C et al. Subjective thirst moderates changes in speed of responding associated with water consumption Front. Hum. Neurosci., 16 July 2013

EFSA Journal 2011: 9(4):2075 Scientific Opinion on the substantiation of health claims related to water and maintenance of normal physical and cognitive functions maintenance of normal thermoregulation and “basic requirement of all living things”

Grandjean AC, Grandjean NR. Dehydration and cognitive performance. J Am Coll Nutr. 2007;26(5 Suppl):549S–554S

Lieberman HR. Hydration and cognition: a critical review and recommendations for future research. J Am Coll Nutr. 2007;26(5 Suppl):555–561S.

Kempton et al, Dehydration Affects Brain Structure and Function in Healthy Adolescents Hum Brain Mapp. 2011 Jan;32(1):71–9. doi: 10.1002/hbm.20999.

Killer, S.C., Blannin, A.K. & Jeukendrup, A.E. 2014. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS ONE 9, e84154.

Mcartney, M. Waterlogged? BMJ 2011; 343

Noakes, T Case proven: exercise associated hyponatraemia is due to overdrinking. So why did it take 20 years before the original evidence was accepted? Br J Sports Med. Jul 2006; 40(7): 567–572.

Popkin et al Water, hydration and health Nutr Rev. Aug 2010; 68(8): 439–458. doi: 10.1111/j.1753–4887.2010.00304.x

Smith M The use of Magnetic Resonance Imagery (MRI) in examining the effects of dehydration on brain structure and function in healthy humans

Sziannai et al Effect of water deprivation on cognitive-motor performance in healthy men and women Am J Physiol Regul Integr Comp Physiol 289:R275–R28

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