If you don’t follow the gossip magazines you may be unaware that coconut water is the latest celebrity health fad with devotees such as Rihanna, Gisele, and Madonna being seen to drink or invest in coconut water. Hyped as a natural source of electrolytes, more hydrating and less bloating than sports drinks, its sales have soared in recent years. Given the claim it is superior to sports drinks a recent study(1) looking at this came at just the right time for us to review.
Background: Sports drinks are a huge industry with manufacturers promoting their products as a means to enhance hydration, performance and provide electrolytes to boost performance. Sports science groups including the ACSM and ISSA have previously issued position statements recommending drinks with a similar nutrient composition to mainstream sports drinks for the purpose of enhancing performance and preventing dehydration (2,3). The combination of this plus the widespread marketing of sports drinks has led to them becoming the favoured choice for athletes, especially those engaged in aerobic training to a high degree (4).
Coconut water is widely consumed across many parts of the world and is rich in minerals including potassium, sodium chloride as well as providing carbohydrates (5), shown to have antioxidant properties (6) as well as providing hydrating effects similar to those of carbohydrate-electrolyte drinks (7).
Objective: This study set out to measure if the hydrating effects of coconut water could also lead to performance outcomes comparable to those of a carbohydrate-electrolyte sports drinks.
Methods: Twelve exercise trained individuals with a history of following a regular exercise program for at least six months were recruited to take part in the study. Those selected were instructed to not use any new supplements but to continue with any pre-existing supplementation. On four separate occasions separated by at least five days, the subjects performed a 60 minute training session on the treadmill designed to dehydrate and received either bottled water (BW), pure coconut water (VitaCoco brand), coconut water from concentrate (CWC), or a carbohydrate-electrolyte sports drink (SD). The study followed a randomised, cross over, single blind design (meaning the subjects did not know what they consumed but the investigators did). The researchers having initially taken measurements for a variety of markers assessed hydration status, and performance based on a treadmill test to exhaustion assessed after rehydration. The researchers also took subjective measurements of thirst, bloatedness, refreshment, stomach upset, and tiredness.
Results Performance Data: No significant differences were observed on exercise time performance between the different groups. The actual results are displayed below showing average times for each group showing the sports drink group had the best average times but not meeting statistical significance.
Bottled Water 11.9 minutes
VitaCoco 12.3 minutes
Coconut water from concentrate 11.9 minutes
Sports drink 12.8 minutes
Results Hydration Data: All subjects in all groups lost approximately 1.7kg during the exercise and regained this mass at a similar weight during the recovery period although body mass and fluid retention were slightly greater in the CWC group. Plasma osmolality displayed similar results to body mass and fluid retention with the CWC showing greater values compare to the bottled water group. An increase in this measure would indicate dehydration with values returning to. Ormal after three hours indicating rehydration of the subjects.
Results Subjective Data: All four protocols quenched thirst while subjects across all four conditions experienced bloatedness one hour after the exercise, not surprising given the consumption of over 2 litres of fluid in a short time frame. After two hours bloatedness decreased for all four protocols but remained statistically significant for the VitaCoco and concentrate groups. Subjects all remarked on feeling refreshed after the consumption of the various beverages with a statistically significant increase for bottled water over VitaCoco at one hour post exercise. Interestingly, the two coconut based drinks produced greater stomach upset than the water or sports drinks protocols. No other significant differences were noted.
This experimental design showed similar capacities for all four drinks beverages for supporting rehydration and performance. Although some minor differences were noted, there were few statistically significant differences between the different drinking protocols. A more extensive training regimen including one based on a time trial test was recommended by the researchers to help determine more specifically the benefits of coconut water versus alternative beverages. For now we can say that for the outcome of most interest to athletes, namely the effect on performance, coconut water was just as good as sports drinks and bottled water, although no better than. For those who like the taste of coconut water it would be fine for using to rehydrate and maintain performance but no special characteristics for coconut water could be observed in this study. With many of the adherents of coconut water consuming it for its purported health benefits, further study would be needed to test the proposition that coconut water has special health benefits above and beyond those related to hydration
1. Douglas S Kalman, Samantha Feldman, Diane R Krieger and Richard J Bloomer (2012): Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained mend
2. Convertino VA, Armstrong LE, Coyle EF, Mack GW, Sawka MN, Senay LC Jr, Sherman WM: American College of Sports Medicine position stand. Exercise and fluid replacement.
3. Kreider RB, Wilborn CD, Taylor L, Campbell B, Almada AL, Collins R, Cooke M, Earnest CP, Greenwood M, Kalman DS, Kerksick CM, Kleiner SM, Leutholtz B, Lopez H, Lowery LM, Mendel R, Smith A, Spano M, Wildman R, Willoughby DS, Ziegenfuss TN, Antonio J: ISSN exercise & sport nutrition review: research & recommendations
4. Von Duvillard SP, Arciero PJ, Tietjen-Smith T, Alford K: Sports drinks, exercise training, and competition.
5. Kuberski T, Roberts A, Linehan B, Bryden RN, Teburae M: Coconut water as a rehydration fluid.
6. Mantena SK, Jagadish , Badduri SR, Siripurapu KB, Unnikrishnan MK: In vitro evaluation of antioxidant properties of Cocos nucifera Linn. water.
7. Saat M et.al: Rehydration after exercise with fresh young coconut water, carbohydrate-electrolyte beverage and plain water.
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