Madonna, Demi and Lara Bingle all swig it, but opinion is divided as to whether coconut water is the wonder health drink some claim it to be.
Advocates say coconut water - the clear liquid inside a young coconut - is a nutritional goldmine. Already popular in Brazil, where sales top $300 million a year, coconut water is one of the fastest-growing new food categories in the UK and sales doubled in the US last year, thanks to investment by Coca-Cola, PepsiCo and Madonna, who poured $1.5 million into the brand Vita Coco and convinced Matthew McConaughey and Demi Moore to do the same.
Not to be confused with coconut milk, the fattier, pulped coconut meat, pure coconut water has been available fresh from health food outlets and in pre-packaged form in Asian supermarkets for years, and has just made its Australian debut in general supermarkets.
The Jamaicans use it as a heart tonic and the United Nations' Food and Agriculture Organisation says it's full of natural electrolytes.
But Tania Ferraretto, an accredited practising dietitian with Nutrition Professionals Australia, says, "At this point I wouldn't recommend coconut water to my clients." Aloysa Hourigan, senior nutritionist with Nutrition Australia, agrees. "I think the claims for coconut water are probably overrated. It's unlikely to be harmful and it has got some mineral component, but it doesn't have a high nutritional content."
It's a low-fat health drink. Deemed a healthy alternative to sugar- and kilojoule-packed soft drinks and juices, pure coconut water is a natural beverage with no artificial additives or sweeteners. It's cholesterol free, 99 per cent fat free, low in carbohydrates and naturally occurring sugars and has less than 100 kilojoules per 100ml (most flavoured varieties use 100 per cent fruit extracts).
It also boasts zinc, selenium, iodine, sulfur, manganese, boron, molybdenum, ascorbic acid and B-group vitamins. But Hourigan says the latter two are not at a substantial level and Ferraretto warns that the bottled source may not be as good as the real deal. "What's the shelf life for all these components and are they still active when they've been on the shelf for a while?" she asks. She says you also need to remember that coconut water is not kilojoule free.
It's better than a sports drink
Dubbed "nature's Gatorade", coconut water is a natural isotonic drink that provides many of the same benefits as formulated sports drinks, including the electrolytes calcium, magnesium, phosphorus, sodium and potassium, but in their natural form.
"While it's a marketing advantage to say it's natural, in the real world your body doesn't distinguish between the electrolytes coming from coconut water or from a sports drink," says Ferraretto. And while a small Malaysian study found it caused less nausea, fullness and stomach upset than sports drinks, and could be used for whole-body rehydration after exercise, she would not yet recommend it for athletes.
"Although it does provide electrolytes and a little bit of carbohydrate, a sports drink is specifically formulated for athletes and the electrolytes and carbohydrates are at the right level." She says the rest of us get all the hydration and electrolytes we need from a healthy diet.
It slows down ageing
Fans say coconut water can promote smoother, more youthful-looking skin. They claim it's a natural source of cytokinins, a group of plant growth hormones that help regulate cell growth, development and ageing. Rich in potassium, antioxidants and lauric acid, cytokinins are said to balance pH levels, strengthen and hydrate connective tissues and even reduce the risk of age-related diseases. Dab it onto skin and you may also reduce acne, cellulite, eczema, stretch marks, wrinkles, age spots and sagging skin. But Hourigan says no scientific studies back any of this up.
It's almost as good as a blood transfusion
According to the UN, coconut water's chemical profile is so similar to blood plasma it has been used intravenously to save lives in developing countries and during World War II. In the Pacific, it was siphoned directly from the nut to provide emergency transfusions for wounded soldiers. It is also used as a home remedy for dehydration-related ailments such as cholera and gastroenteritis, although a West Indian study warned against using it in severe cases. "When medical saline isn't available it can replace water and salt," Hourigan agrees. "But it doesn't contribute enough glucose."
Regulates blood pressure, blood sugar and cholesterol
Research shows that coconut water can improve blood circulation, lower elevated blood pressure and reduce the risk of heart attacks and strokes, says Dr Bruce Fife, director of the Coconut Research Center and author of Coconut Water For Health And Healing (Perfect Paperback). Advocates also claim it helps increase HDL (good) cholesterol, reduces plaque formation, moderates sugar absorption and improves insulin sensitivity. "People at risk of high blood pressure and stroke need more potassium and less sodium, but I'd like to see more studies on [coconut water and] cholesterol and diabetes," Ferraretto says.
Good for digestive and urinary health
Coconut water claims to be a cure-all for a range of digestive and urinary ailments and has been used in the tropics to treat stomach flu, dysentery, indigestion, constipation, intestinal worms, bladder infections and malfunctioning kidneys. It's a natural diuretic and is said to prevent urinary tract infections (UTIs) and kidney stones. Research from the Philippines found drinking coconut water up to three times a week may reduce stone size and the need for surgery.
Ferraretto argues that water is better for hydration and urine flow and says if you're worried about UTIs, try cranberry juice. "We know there's some evidence there," she says. Coconut water is considered safe for children as well as pregnant and breastfeeding women and there are no known side effects, however there are some things to watch out for:
- The fresher the coconut water, the better. Once exposed to air and warm temperatures, it rapidly ferments and loses its nutritional value.
- If you have nut allergies, check with your GP.
- Avoid coconut oil if you have heart disease, kidney disease or are on a low-potassium diet. Regulate your potassium levels if you consume coconut water and potassium supplements, as too much potassium can impact on the heart.
- It may have a laxative effect.