Coconut Waters Review
Initial Posting: 4/5/19
Sections: Jump to a section by clicking on its name.
- What is it? Coconut water is the clear to slightly cloudy liquid found in immature (green) coconuts. It is rich in potassium, contains a moderate amount of sugar, and modest amounts of sodium, magnesium, calcium, vitamin C, and phosphorus. Unlike coconut milk and coconut oil, it contains very little fat — less than 1 gram per cup. See What It Is.
- How is it used? Drinking coconut water is a pleasant way to hydrate and re-hydrate but has generally not been shown to be better than water in this regard. Although preliminary research suggested a possible role for coconut water in preventing kidney stone formation, this has not been proven in people. See What It Does.
- What did CL find? Among six popular coconut water products tested by ConsumerLab, five were found to contain what they claimed with regard to sugar and key minerals and none was contaminated with arsenic, cadmium, or lead. One product was found to contain significantly less sugar than claimed. Based on a one cup serving, the products contained 6.7 to 11 grams of sugar, 284.7 to 490 mg of potassium, 20 to 112 mg of sodium, and 6.9 to 66.7 mg of magnesium -- although the higher amounts of sodium and magnesium were in a product in which these were added ingredients. The cost per cup ranged from 72 cents to $1.98. See What CL Found.
- Top Picks — ConsumerLab selected a Top Pick among coconut waters based on quality, nutrient levels, taste, and cost.
- How to store? Coconut water does not have to be refrigerated until the container is opened. See ConsumerTips.
- Cautions: Due to the large amount of potassium in coconut water, intake should be limited among people with severe kidney disease or on medications that affect potassium levels. Even healthy people should consume coconut water in moderation and be aware that it will not adequately replace sodium after long, strenuous exercise and can have a laxative effect. For details, see Concerns and Cautions.
What It Is:
Coconut water is the clear to slightly cloudy liquid that sloshes around inside immature (green) coconuts. You can drink it straight from the coconut or get in in bottles, cans, Tetra Pak cartons, and even as a powder.
Coconut water offers an unusual blend of nutrients. It's especially rich in potassium. Based on our findings in this Review, one cup provides about 400-500 mg, roughly what you'd get from a banana or a cup of orange juice. It also contains some sodium (about 30-53 mg), magnesium (about 7-23 mg), calcium, and small amounts of phosphorus and vitamin C. It contains no cholesterol and almost no fat. Natural sugars (about 7-9 mg) make it mildly sweet, although it is relatively low in calories compared to typical fruit juices. Coconut water is very different from coconut milk, which is made from the pressed meat of mature coconuts and contains significant amounts of fat from coconut oils.
How It's Used:
Coconut water is a refreshing drink. Because it contains sugar as well as potassium and other electrolytes, it is sometimes marketed as a sports drink for rehydration during and after exercise, although, as noted below, it may not be much better than plain water. It may also be sought out by people who want more potassium in their diets. (See ConsumerLab.com's Review of Potassium Supplements for more information about potassium.)
Rehydration — How Good is Coconut Water?
When you sweat, you lose minerals as well as water. It only makes sense that a combination of water and minerals is the best way to replenish your supplies. The main mineral in sweat is sodium. In fact, there is about ten times as much sodium in sweat as potassium. So is potassium-rich coconut water really a good way to rehydrate? Several small suggest that it is -- although it is not necessarily better than plain water.
A study that compared coconut water to both plain water and a rehydration drink containing about four times more sodium but far less potassium than coconut water found that all three provided adequate rehydration after a 2-hour period of exercise-induced dehydration (Saat, J Physio Anthro 2002). However, blood sugar levels were restored faster with coconut water and the rehydration drink than with water. An advantage of the coconut water was its palatability. Subjects found it to be sweeter than the sports drink, and it was less likely to upset their stomachs.
Similarly, a small study found that in young healthy men who performed a 1-hour exercise protocol designed to induce dehydration, pure coconut water (VitaCoco®), coconut water from concentrate, and bottled water each provided similar rehydrating effects compared to a sports rehydration drink (Gatorade®) (Kalman, J Int Sports Soc Nutr 2012), although subjects reported more bloating and stomach upset after drinking both forms of coconut water.
Sodium-enriched coconut water was reported in one small study to provide rehydration (after a 1.5-hour period of exercise-induced dehydration) similar to a sports drink or coconut water not enriched with sodium - each of which restored hydration within two hours of consumption, compared to plain water, which did not. The sodium-enriched coconut water also caused less stomach upset than the sports drink or water (Ismail, Southeast Asian J Trop Med Public Health 2007).
However, the generally small amount of sodium in most non sodium-enriched coconut water products should still be a concern for anyone trying to rehydrate after long-duration, strenuous exercise. Rehydration drinks like Gatorade typically contain 110 mg of sodium per an 8 oz cup (240 mL) serving, and even greater amounts may be useful. Commercial coconut waters made from pure coconut water (not concentrate) contain only about one-third to one-half that amount. And because coconut water is very low in protein or branched chain amino acids, it should also not be considered a sports "recovery" drink to rebuild muscle protein. In large amounts, coconut water may have a mild laxative effect. Obviously, this would make it less effective at replenishing fluids in large volumes.
Muscle cramps and restless legs syndrome
Because potassium deficiency may cause muscle spasms, coconut water has been promoted as way to avoid or treat muscle cramps. However, there are no good studies on the effects of coconut water on muscle cramps. Furthermore, nighttime muscle cramps and exercise-related muscle cramps do not appear to be related to potassium levels (Allen, Am Fam Physician 2012). Similarly, coconut water has been proposed to treat restless legs syndrome (RLS), a condition that causes uncomfortable "creepy-crawly" sensations, agitation, and the need to move the legs when trying to fall asleep. Once again, however, there are no good studies on the effects of coconut water on the symptoms of restless legs. (One small study suggested taking a potassium supplement might reduce the symptoms of restless legs syndrome, but it did not include a control group, so it's not possible to draw a conclusion from it -- see the Potassium Supplements Review). Be aware that getting too much potassium has actually been reported to cause leg cramps (see Concerns and Cautions).
Prevention and Treatment of Kidney Stones?
Although preliminary research has suggested a possible role for coconut water in preventing kidney stone formation, and some websites claim it can "dissolve" kidney stones, none of this has been proven in people. A study in an experimental rat model showed that coconut water inhibited formation of crystals in the kidney (Gandhi, Int Braz J Urol 2013). A study in healthy adults focused on the ability of coconut water to increase citrate in the urine, as citrate can block the formation of kidney stones. For four days, participants consumed 2 liters (about 8 cups) of coconut water daily. This was switched to tap water for another four days. Compared to tap water, coconut water increased citrate in the urine by an average of 29% (161 mg per day) and, not surprisingly, potassium increased by even more -- by 130%. However, this is not an efficient way to increase urinary citrate: Orange juice is about 4 times as efficient (a single cup can increase citrate by 88 mg); the coconut water provided an extra 108 grams per day of carbohydrates, which was mostly sugar, contributing 416 Calories. Furthermore, this approach could be dangerous for people who need to restrict their potassium intake (Patel, Biomed Res Int 2018).
Quality Concerns and What CL Tested:
Because coconut water is a natural food product, many different factors can affect the nutritional content. To assess the accuracy of the nutritional labeling of coconut waters, ConsumerLab.com purchased six popular coconut water products, one of which was in powder form. We tested levels of sugars, potassium, sodium, and magnesium. Products were also checked for potential contamination with arsenic, lead, and cadmium.
What CL Found:
Among the six products tested, all of the liquids passed our tests, but a powdered product (Big Tree Farms Coco Hydro) provided 2.5 grams less sugar per cup than listed. Overall, this is an improvement since our last review in 2011 in which only one of three popular coconut waters passed all of our tests because two products failed to provide minerals in the amounts claimed on their labels.
None of the products was contaminated with heavy metals and all are generally safe to use in moderation. However, there were some significant differences among the products in terms of cost, taste, appearance and amounts of sugars and minerals, as discussed below. Be aware that the suggested serving sizes of coconut waters vary by product, ranging from one cup (8 fl. oz. or 240 mL) to about twice that amount (e.g., a full 500 mL bottle of Zico). To help you compare "coconuts to coconuts," the discussions and graphs below are based on what you would get from one 8 fl. oz. cup of each product.
As shown in the graph below, the amount of sugar in a cup of coconut water ranged from 6.7 grams in Naked to 11 grams in Trader Joe's — 64% more sugar than in Naked. Not surprisingly, the two products with the most sugar had sugar listed as an added ingredient: Trader Joe's (lists "fructose") and Vita Coco (lists "organic sugar"). The only other product with added sugar was Big Tree Farms Coco Hydro, a powder, which lists "dextrose" as an ingredient. According to its label, a cup of coconut water made from this powder (by mixing two tablespoons of powder in 12 ounces of water) should contain 10.7 grams of sugar but we found only 8.2 grams — the second-lowest amount of sugar per cup in the group.
Each gram of sugar contributes about 4 Calories, so an extra 4 grams of sugar is an extra 16 Calories per cup. Be aware that coconut water naturally contains an additional gram or two of other carbohydrates, which are reflected in the total Calorie counts on labels.
Coconut water is a real star when it comes to potassium, as one cup (8 fl. oz) typically provides about 400 to 500 mg of potassium. This is about 20% of the daily potassium requirement for women and about 13% for men, based on the latest daily requirements of 2,300 mg for women and 3,400 mg for men (Note: These daily requirements were established in March, 2019. The previous requirements, set in 2005, were higher — 4,700 mg and 5,100 mg. The Daily Values (DVs) currently shown on product labels still reflect the older daily requirements.)
As shown in the graph below, there is some variation in the potassium content of coconut waters, although even those with the lowest amounts per cup provide significant amounts.
Sodium and Magnesium
While coconut waters have been touted for the electrolytes sodium and magnesium, they actually contribute only small percentages per cup of the daily requirements of these minerals, which are 1,500 mg for sodium and 320 mg and 420 mg for magnesium, respectively, for women and men over 30 years old.
As shown in the graph below, sodium per cup ranged from just 30 to 52.8 mg among liquid coconut waters and was 112 mg in Big Tree Farms which has added "sea salt." Aside from Big Tree Farms, these amounts are much lower than you would get from a sports drink like Gatorade that provides 110 mg of sodium per cup.
Magnesium per cup ranged from just 6.9 mg to 23.3 mg among liquid products and was 66.7 mg for Big Tree Farms which has added "magnesium phosphate."
Coconut waters are not cheap. As shown below, the lowest cost to get a cup of coconut water was 72 cents from Big Tree Farms, followed closely by Trader Joe's at 75 cents. The highest cost was $1.98 from Taste Nirvana. The others fell between $1.15 and $1.72.
Taste and Appearance
Coconut water is typically consumed cold, but ConsumerLab staff drank the products at room temperature to get a better sense of their inherent tastes. The first thing we noticed though, was a slight variation in the colors — clear in some but pale yellow in Trader Joe's and Vita Coco, pink in Zico, and amber in Naked. Clarity ranged from clear to cloudy. See the Results table for details.
All of the products had a coconut flavor, but this was strongest in Taste Nirvana, followed by Zico. All were somewhat sweet, but this was most noticeable in Taste Nirvana, Trader Joe's and Big Tree Farms, although only Trade Joe's had relatively high sugar content. Trader Joe's and Vita Coco were also slightly sour, although not unpleasantly so, and this might correspond to their yellow tints, suggesting more oxidation than the others. The only real negative to come out of the taste tests was a wateriness in the taste of Big Tree Farms, but this is likely an inherent problem of making coconut water from a powder.
It is difficult to select a Top Pick among these products, as all are generally pleasant tasting and safe when used in moderation. They are certainly a healthier choice than a can of soda or a fruit drink, which can contain twice the amount of sugar (a 12 oz, or 355 mL, can of Coke has 39 grams of sugar!). However, our Top Pick is Naked Pure Coconut Water despite it being relatively expensive at $1.72 per cup ($3.59 per 500 ml carton). The reasons we like it are 1) it is lowest in sugar while providing a mildly sweet coconut flavor; 2) it provides average or above average amounts of sodium and magnesium compared to other natural coconut waters; 3) it is certified as USDA Organic (as is Vita Coco); and, 4) it claims to naturally provide more calcium (10% of the Daily Value) compared to the others (2% to 6% of the Daily Value), although we did not test calcium levels -- we may next time.
If you prefer a coconut water that's a little sweeter, we suggest Zico. It's also less expensive ($1.24 per cup; $2.59 per 500 mL bottle) than Naked, although it is not organic and provides less magnesium and less calcium.
If you want the strongest coconut flavor, go with Taste Nirvana Premium Coconut Water, although it is the most expensive coconut water we tested ($1.98 per cup: $2.30 per 280 mL bottle).
If you are just adding coconut water to a drink, such as a smoothie, and are looking to save money, we suggest Trade Joe's Coconut Water, which is just 75 cents per cup ($2.99 per 33.8 fl. oz. carton).
Test Results by Product:
Listed below are the test results of the six coconut waters selected for review by ConsumerLab.com, listed alphabetically. Also shown are the labeled serving sizes and claimed amounts of the key nutrients. If a product is listed as Approved, it was found to contain the labeled amounts of tested nutrients (sugar, potassium, sodium, and magnesium) and did not exceed CL's stringent criteria for contamination with arsenic, cadmium, and lead. For more information about testing go to How Products Were Evaluated.
What to Consider When Buying and Using:
Coconut water does not have to be refrigerated until the container is opened. Once opened and refrigerated it may sour over a period of days, so plan on using it up within a day or two.
Concerns and Cautions:
Coconut waters can contain high amounts of potassium and, as noted earlier, in large amounts, coconut water may have a mild laxative effect.
People with severe kidney disease, those taking certain medications, including ACE inhibitors (captopril, lisinopril, enalapril) and potassium-sparing diuretics (e.g., triamterene or spironolactone) or other people who need to limit potassium intake should consult a physician. People with type 2 diabetes, especially those with kidney impairment or who take potassium-sparing diuretics, are also at an increased risk of developing high blood levels of potassium from the consumption of coconut water (Devgun, Pract Diabetes 2016). A 78-year-old man with coronary artery disease and type 2 diabetes who was taking spironolactone as well as other medications developed life-threatening high blood levels of potassium resulting in an irregular heartbeat, kidney failure, muscle weakness, and paralysis after consuming 2 - 4 servings of coconut water daily for one week. He recovered completely after medical treatment (Hemachandra, Case Rep Neurol Med 2018). In addition, a 62-year-old man in England with type 2 diabetes (without kidney disease) developed high potassium levels after consuming 1 liter (two 500 mL servings of VitaCoco) daily for two months (Devgun, Pract Diabetes 2015). His potassium levels returned to normal within several months after he stopped drinking coconut water.
Even in people without kidney disease, consuming excessive amounts of coconut water (and therefore, potassium) can be dangerous. A healthy, 42-year-old man in the U.S. was admitted to the emergency room for fainting after consuming eight 11-ounce bottles of coconut water (containing a total of 5.5 grams of potassium) in one day while playing tennis outdoors in hot weather. Tests revealed he had dangerously high blood levels of potassium, an abnormal heart rhythm, rhabdomyolysis (muscle breakdown), and acute kidney damage (Hakimian, Circ Arrhythm Electrophysiol 2014). He was released after 3 days of treatment in critical care, and advised to "avoid coconut water, remain well hydrated, and avoid excessive exercise in the extreme heat." A case of leg cramps was reported in a woman in Japan who consumed a mango (a potassium-rich fruit) every night before bed for one month and developed elevated potassium levels. The cramps resolved after she stopped eating mangos and her potassium levels returned to normal (Abe, Case Rep Neurol Med 2012).
(See the Encyclopedia article for more about potassium side effects and drug interactions).
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