Wednesday, February 5, 2014

Hydrated or Dumb: Dehydration Affects Brain, Muscle and Other Vital Organs - Plus: 15+ Causes of Dehydration + Can the Color of Your Urine Tell You if You Drink Enough?

If you want to stay smart, you should join hands w/ water!
Those of you who are following the 10+ SuppVersity Facebook news on a daily basis, will remember my post about the recent paper - co-authored by Brad Schoenfeld (Ribeiro. 2014) - about the significant "water gain" after workouts. I wrote about that myself, a couple of weeks before in "Cell Swelling Keeps Muscles "Pumped" For More Than 52h. Size Increases of Up to 16% After a Single Leg Workout!" | read more, and mentioned that the intra-muscular swelling is probably a necessary prerequisite, if not driver of skeletal muscle growth.

In today's SuppVersity article, I will now take a step back, away from the musclehead's only interest and peek at other health aspects that are influenced by the hydration status not just of your muscles, but of your whole body.
Hydration Tip of the Century: Many of you will accidentally (or because they read it here, at the SuppVersity, before) already follow this advice, but I still would like to emphasize that the dairy protein you're probably consuming after your workout is not only going to boost your muscle, but also your "water" (=positive hydration) gains. In 2010 James et al. were able to show just that: A post-workout beverage with 40 g/l carbohydrate + 25 g/l milk protein are more effective at augmenting fluid retention than 65g of pure carbs carbohydrate (James, 2010).
In one of the most recent papers on this issue, Natalie A. Masento and her colleagues from the University of Reading reviewed the surprisingly profound effect of dehydration on cognition and mood, of which Masento et al. write that it is "particularly relevant for those with poor fluid regulation, such as the elderly and children" (Masento. 2014).
"With evidence to suggest that individuals are routinely at a risk of mild dehydration day to day (Greenleaf. 1965), particularly vulnerable populations such as children and older adults, there has been an increased interest in studying whether additional water consumption might benefit cognitive performance. The small collection of published water intervention studies involving either young adults or school children report consistent positive effects of water intervention on particular cognitive abilities" (Masento. 2014)
If you take a look at the overview, the researchers compiled (it's too long and eventually repetitive to post it here), you will find studies everything from self-reported fatigue, tiredness and headaches to objectively measured declines in cognitive performance, eye-hand coordination, word recognition, visual attention and - as mentioned in the previously cited article physical performance markers, such as grip strength.

How come? I mean, why does dehydration have such a profound impact?

The above, probably is the question that's preying on your mind right now and I have to admit, I have - just like the researchers from the University of Reading - no conclusive, water-tight *pun intended* answer to that question.
"Despite the expansion of this research area, we still do not have a clear understanding as to how acute water intervention may influence mental performance and its associated neural activity. Researchers have suggested psychological mechanisms related to limited attentional resources during thirst. However, evidence has also highlighted the  importance of physiological mechanisms, with findings that the expectancy of water alone does not influence cognitive performance." (Masento. 2014)
Hitherto proposed mechanisms include references to the Global Workspace Model (Baars. 1993) and being distracted by the often subconscious thought "Where do I find water".

Gray matter activation clusters in dehydration (Streibürger. 2012).
Of potentially greater interest (at least to me) are theories that involve physiological mechanisms, such as the already confirmed...
  • shrinkage of total brain volume shrinkage (Streitbürger. 2012; Kempton. 2011) and 
  • over-recruitment of specific brain areas during cognitively demanding tasks,
as well as other significant changes at the neural level which contribute to the previously mentioned decline in cognitive performance and awareness (Kempton. 2011).

Luckily, these changes can be reversed by the provision of water in minutes, as long as the subjects are only mildly dehydrated. In view of the
"lack of data related to baseline hydration states of individuals and no further published work using imaging techniques to examine hydration state" (Masento. 2014) 
We do yet once more have to acknowledge that "we know that we know nothing" or, put differently, that these proposed mechanisms are merely speculative.
Potential causes of dehydration: It's not just working out in the heat or simply forgetting to drink (very common in the elderly), there is a multitude of other things that promote dehydration and here are a couple of examples: ✋Low sodium + chloride (can't store water), ✋high calcium, magnesium, zinc, chromium intake, ✋ extreme high sodium or potassium intake, ✋low phosphor intake; ✋high vitamin D, pantothenic acid (B5), pyridoxine (B6) intake; ✋low adrenal output; ✋high protein intakes (esp. when protein is abused as energy source); ✋laxatives, diuretics or other meds or supps -- One thing, however, does not cause dehydration: ☕ Coffee!
Another physiological mechanism that has been suggested is the albeit age-dependent reaction of the central nervous system in response to the ingestion of significant (500ml) amounts of water, of wich May & Jordan found that it causes
  • a significant drop in heart rate and an increase in vasodilation in young adults (May. 2011), and the opposite effects, i.e.
  • a significant increase in blood pressure in the healthy old subjects in a 2002 study by Schroeder et al. (Schroeder. 2002)
- whether this difference may be brought about by different baseline hydration status, is not clear. What is obvious, though, is that the cardiovascular reactivity promotes cerebral blood flow, which, in turn, will encourage the circulation of substances such as oxygen and glucose that are known to stimulate neural activity and associated behavioural performance (Gold. .1995) in healthy, non-diabetic individuals.

If you think about this hypothesis, i.e. the beneficial effects of water-induced increases, and the detrimental effects of reductions in glucose and oxygen availability in the brain and other organs that would occur, even upon mild dehydration, it seems perfectly logical, a mechanism similar to that has after all been proposed to account for the improved cognitive function due to physical exercise (Kashihara. 2009).
The urine color chart is a valuable tool to judge your hydration status (Wakefield. 2002)
"So how much water to I need?" -- I know. I am mean... the question that's been preying on your mind ever since the introduction. I still did not answer it - right?

Well, you can find the answer in your toilet bowel (see color chart on the right for a guide). You just have to check the color of your urine to know if you're drinking enough... well, at least if you didn't have beets, which will turn it red-brown or red, blackberries, which will give it a red tinge, carrots, which will produce a rusty yellow, paprika, which will make it look orange, rhubarb, which turns it re-brown, then orange, sometimes even yellow-pink, rusty or yellow-brown... and of course the nasty neon-green that's caused by the tons of useless riboflavin (aka vitamin B2) in your urine.
  • Baars, Bernard J. "How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of." Experimental and theoretical studies of consciousness 174 (1993): 282.
  • Greenleaf, John E., and Frederick Sargent. "Voluntary dehydration in man." Journal of Applied Physiology 20.4 (1965): 719-724.
  • Kempton, Matthew J., et al. "Dehydration affects brain structure and function in healthy adolescents." Human brain mapping 32.1 (2011): 71-79. 
  • Masento et al. "Effects of hydration status on cognitive performance and mood". British Journal of Nutrition (2014) [ahead of print].
  • Ribeiro, Alex S., et al. "Resistance training promotes increase in intracellular hydration in men and women." European Journal of Sport Science ahead-of-print (2014): 1-8.
  • Schroeder, Christoph, et al. "Water drinking acutely improves orthostatic tolerance in healthy subjects." Circulation 106.22 (2002): 2806-2811.
  • Streitbürger, Daniel-Paolo, et al. "Investigating structural brain changes of dehydration using voxel-based morphometry." PloS one 7.8 (2012): e44195.
  • Wakefield, Bonnie, et al. "Monitoring hydration status in elderly veterans." Western Journal of Nursing Research 24.2 (2002): 132-142.