Going (coco)nuts for re-hydration

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Travis’ Note: Today’s guest post comes from Allana Leblanc.  You can find out more about Allana at the bottom of this post.  You can find out how to submit your own Obesity Panacea guest post here.

Over the past year or so, coconut water has hit the ‘main stream’ so to speak. It’s a) everywhere b) the next power food and c) (and most importantly) trendy. Oh so trendy.  I love all things trendy, especially when they are food related and ESPECIALLY when they’re food AND health related.

With this ‘flood’ of popularity, a lot of my friends have recently asked if coconut water was in fact, ‘all it was cracked up to be’. Every time I was asked, I mumbled something incoherent, pretended to check my phone, or flat out ignore them.

Until now. Well really until last Sunday, which happened to be the morning after a ‘welcome back’ gathering to celebrate yet another year of post-secondary education. That was when I could no longer resist the cool, refreshing siren of ‘ultimate hydration’. After a quick trip to my corner store, I sent Travis a message asking if he’d let me write a post about coconut water.  First he tried to convince me to just start my own blog, but with the promise of leaving him alone for the conceivable future, he said yes.  And so, we have a match up

Coconut water vs. tap water:

An all-out battle for satisfaction, hydration and performance.

First up, meet the players.

Coconut water

Full disclosure: I’m under no financial, ethical or moral obligation to Grace Coconut Water, it was just the only brand available to me at the time of purchase.

Cost: $0.99/310 mL can

Nutritional Facts:

Ingredients: Coconut water, water, ascorbic acid (vitamin C), sodium metabisulphite (to

retain colour)

Taste: slightly denser than water, authentic coconut flavour, hint of something I just can’t put my finger on.

Other interesting tidbits from the can: no sugar added, no pulp, 6 essential electrolytes, gluten free, low in sodium, ‘ultimate hydration’

Tap water

 Cost: $0.00 (water is included in my rent)

Nutritional facts: (taken from the 2011 drinking water quality tests found here )

Taste: like chicken? Not really but water is a hard thing to describe.

Other interesting tidbits from the can: N/A (although from general knowledge, I can say it’s low in sodium, gluten free, no sugar added, no pulp)

The science:

Although there are many claims that coconut water can do everything from general re-hydration to the prevention of early ageing (thank you Google), I decided to stick to the more conservative claims and check out what evidence was available for the benefits of coconut water before, during and after physical activity.

When we participate in high levels of physical activity, we sweat. As such, it’s well understood that before, during and after exercise we need to replenish our body with fluid.  While for the most part, it’s pretty clear that water is good enough, there are cases where you’d like ‘a bit more’. Say a run on a particularly hot and humid day or a strenuous activity that lasts well over 60 minutes.

In comes a sports drink (thanks to Dr. Freedhoff over at Weighty Matters, see the composition of your average sport drink here). Want a more natural alternative? In comes coconut water. High in potassium, a sprinkle of sodium and just under one serving of carbohydrates (12 g/310mL).

Sounds great, but does it work? In an article by Kalman1 and colleagues, apparently not. In young, healthy, active men, coconut water provided no additional hydration or performance benefits over either plain water or a sportsdrink. Further, participants reported feeling more bloated after drinking the coconut water (both natural and from concentrate) than after drinking the water or the sports drink.  Another study by Saat2 reported similar results (also in healthy, active young males) and stated that coconut water had no different effects on post exercise hydration status compared to water or a sports drink. But, in contrast Kalman, they reported that coconut water was easier to ingest and was associated with less bloating than water or the sports drink.

So no discernable benefits on hydration status or performance – what the K+? Coconut water does contain a lot of potassium (e.g. K+). Why does that matter?  Potassium is a major player in maintaining fluid and electrolyte balance as well as cell integrity.3 It is also integral in nerve impulse transmission and muscle contraction.  (That being said, a recent review suggests that exercise associated muscle cramping is actually due to neuromuscular fatigue rather than “electrolyte depletion” or “dehydration”4). Diets high in potassium can also help to prevent and control high blood pressure.

Where do you find potassium? As per most macronutrients, fresh fruits and veggies are a pretty good source. Which brings us back to the coconut water. Although technically it’s canned and not fresh, the ascorbic acid acts as a preservative and helps maintain a high level of potassium.  But remember, it’s still canned and therefore still a ‘juice’ of sorts (see a previous post by Travis regarding the “naturalness” of juice here).  And it’s worth noting that if you’re getting enough potassium from the foods you eat on a daily basis, then there is no reason to expect any additional health or performance benefits from consuming extra potassium (and extra calories) in the form of coconut water.

In conclusion…

First let me apologize as this was far from a systematic review of the available evidence. But truth be told, there isn’t a ton of evidence out there. As such, I presented you with two well-designed (cross-over) studies looking at the effect of coconut water on re-hydration and performance. In the land of systematic reviews, that would be some high quality evidence to show no benefit of coconut water over usual care (i.e. water). That being said, coconut water was also no worse than water. And if you are concerned about calories and/or sugar, coconut water clearly comes out on top when compared to any ‘sports drink’ (although it still has more calories than plain water).

WWAD (what would Allana do)? I’d drink water 98% of the time, and when I wanted something a little special, I’d reach for a can of ‘ultimate hydration’.

Allana Leblanc, MSc, CEP

About the Author: Allana LeBlanc is a Certified Exercise Physiologist, PhD Student and semi-regular contributor to Obesity Panacea.  You can find a list of all her guest posts here.

References

1. Kalman DS, Feldman S, Krieger DR, Bloomer RJ. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. J Int Soc Sports Nutr. 2012; 9: 1.

2. Saat M, Singh R, Sirisinghe RG, Nawawi M. Rehydration after exercise with fresh young coconut water, carbohydrate-electrolyte beverage and plain water. J Physiol Anthropol Appl Human Sci. 2002 Mar;21(2):93-104.

3.  Whitener E, Rady Rolfes A. Understanding Nutrition, tenth edition. Thomson Wadsworth. 2005, p. 411-412.

4.  Schwellnus MP. Cause of exercise associated muscle cramps (EAMC)–altered neuromuscular control, dehydration or electrolyte depletion? Br J Sports Med. 2009 Jun;43(6):401-8.

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