Coconut water is said to be a “superior form of rehydration”, a “natural sports drink” and a low carbohydrate alternative to juices. It has gained in popularity the last few years and has grown into a multibillion-dollar global industry. This growth is in line with trend that consumers are looking for more pure ‘organic’ products. There is more competition and there are many ways to adulterate the product (adding sugar, adding electrolytes, adding water). This article will address 2 questions:
How “natural” and “pure” is coconut water. A recent study suggests that it may not always be as “natural” as we think.
Is coconut water really superior to water as a rehydration beverage?
In a recently published study (1) 30 authentic coconut waters (extracted from coconuts in the lab) were analysed as well as 24 commercial coconut waters (bottled) purchased from grocery stores. The researchers measured the carbon isotope range of pulp, total sugars, sucrose, glucose and fructose. This analysis can reveal if sugars were added to the coconut water. A whopping 38% of the coconut waters tested was adulterated (i.e, sugars were added to the water). This analysis only focussed on sugars, so one wonders what happens with dilution of coconut waters, and the addition of salts.
Then there is the second question: is it really a superior rehydration beverage? The claims are based on the fact that coconut water contains electrolytes and some carbohydrate. Below are estimations of the composition of water, a sports drink and coconut water. Coconut water contains a lot of potassium but this has little role in the rehydration process. Sodium, which is important for absorption of fluid and for fluid retention, is low in coconut water. Carbohydrate content is also low, maybe a little too low for rehydration purposes as studies have shown more rapid restoration of fluid balance with higher concentrations of carbohydrate (2, 3).
It must also be noted that coconut water varies tremendously in the composition depending on many factors including the maturation process 4, so the values below are just rough figures of an average coconut water.
Although the composition varies throughout maturations, at no instance did the coconut water contain sodium and glucose concentrations of potential value as an oral rehydration solution (4).
Studies confirm this and found that the hydrating properties of coconut water are not different from those of water (5). When sodium was added to coconut water the hydrating properties improved and the sodium enriched coconut water resulted in more complete hydration than plain water (6).
Therefore claims that coconut water is a superior source of hydration are unfounded. However, it is a natural way to restore fluid balance and it contains some carbohydrate and electrolytes…. “Natural”, if you can find an unadulterated source of coconut water…
References
1. Psomiadis D, Zisi N, Koger C, et al. Sugar-specific carbon isotope ratio analysis of coconut waters for authentication purposes. J Food Sci Technol 2018; 55(8):2994-3000.
2. Osterberg KL, Pallardy SE, Johnson RJ, et al. Carbohydrate exerts a mild influence on fluid retention following exercise-induced dehydration. J Appl Physiol (1985) 2010;108(2):245-50.
3. Evans GH, Shirreffs SM, Maughan RJ. Postexercise rehydration in man: the effects of osmolality and carbohydrate content of ingested drinks. Nutrition 2009; 25(9):905-13.
4. Fagundes Neto U, Franco L, Tabacow K, et al. Negative findings for use of coconut water as an oral rehydration solution in childhood diarrhea. J Am Coll Nutr 1993;12(2):190-3.
5. Kalman DS, Feldman S, Krieger DR, et al. 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):1.
6. Ismail I, Singh R, Sirisinghe RG. Rehydration with sodium-enriched coconut water after exercise-induced dehydration. Southeast Asian J Trop Med Public Health 2007; 38(4):769-85.