When early European explorers tossed a few coconuts on-board for the journey back from the tropics, they could scarcely have imagined what they were starting. Today we are obsessed with all things coconut. It's the food fad that just won't quit.

Just look at the figures. Over the past three years in Britain, our annual spending on coconut water has surged from &3.9 million to almost &33 million, according to consumer research group Kantar Worldpanel. Our appetite for coconut oil is equally unquenchable; sales rose from around &1 million to &16.4 million over the same period.

Even more recent figures report we now spend more than &100 million a year on coconut products: &64 million on coconut water alone, a 64 per cent increase in just one year.

It's not that coconut love is new, of course. Whether we're munching the delicious flesh straight from the shell on holiday or splashing the sweet, creamy milk into a Thai green curry at home, coconut has long been a favourite ingredient - especially in south-east Asia, India, Africa and South America. And the oil has been used as a substitute for butter in vegan cooking for years.

But the real boom stems from the coconut's rise from speciality ingredient to poster child of the free-from and "wellness" movements. "Coconut is gluten free and lactose free, so it's boomed on the back of the free-from trend," says Wayne Edwards, director of food trend agency thefoodpeople.

"Celebrity endorsements from people like Gwyneth Paltrow have raised awareness about coconut. But increasingly it's wellness bloggers - people like Deliciously Ella and the Hemsley sisters - who have had a huge impact, especially in the under-35 age group." The Hemsleys praise coconut oil as having "incredible" health properties and use it liberally in sweet and savoury recipes, as well as a beauty product.

But it's not just coconut oil and water we're mad for; you name it, there's a coconut version of it out there. Coconut milk lattes are on the menu at Starbucks, while coconut flour - once tricky to find outside health food shops - is widely available in supermarkets. The stuff is everywhere: coconut yogurt, coconut cream, coconut chips and coconut chunks, as well as coconut-flavoured coffee, tea, vodka and more. Marks & Spencer has even launched "the high street's first drinking coconut" - a whole coconut with a ring-pull, so you can stick your straw in and pretend you're on the beach.

Coconut palm sugar, made from the sap of the tree, is poised to be the next big coconut thing, according to Stephanie Mattucci, from consumer research group Mintel. Although Diabetes UK and the American Diabetes Association stress it's just another form of sugar, many of us don't believe them. "In the US, 20 per cent of consumers think coconut sugar is good for health," Mattucci says.

And there's the rub. Coconut's purported health benefits range from fighting infection and aiding weight loss to curing dementia and cancer. Some websites claim coconut water can be injected to fight dehydration (nope, sorry), while Paltrow even cleans her teeth with the oil.

But are any of the health claims true? The evidence is sparse, according to food scientists. Coconut oil is almost pure saturated fat, a much more concentrated source than either butter or lard. While saturated fat is no longer the dietary demon we once thought it was, coconut oil is no health food and should be consumed in moderation.

"There is nothing special about coconut fat and it should be treated like all other saturated fats when consumed in the diet," says Dr Scott Harding, lecturer in diabetes and nutritional science at King's College London. "From a strictly cooking perspective, as long as total calorie intake is healthy and people are eating a balanced diet with good variety, there is no reason to fear any cooking fat or oil."

Coconut water, the juice inside young coconuts, has also been hyped as a miracle drink. But again, experts say there's no evidence to support the health claims.

"Coconut water does contain electrolytes like potassium and magnesium that are quite good if you have been sweating," says Sophie Claessens, registered dietitian and spokesman for the British Dietetic Association. "But you could achieve the same thing or better with a banana or piece of peanut butter toast and a glass of water, milk or juice. Coconut water is expensive and unnecessary, so I don't recommend using it."

One question mark hanging over the coconut craze is: can coconut supplies keep up? Possibly not, as tree numbers are falling due to old age, disease and bad weather. "Governments of coconut-producing countries would need to step up the support provided to growers to ensure that the booming demand does not have irreversible consequences on the environment and place unrealistic and risky demands on family-based farms," says Tim Aldred, the Fairtrade Foundation's head of policy and research. Consumers should buy Fairtrade so farmers can reinvest the extra money they earn on sustainable farming practices, he says.

Lucy Bee, co-founder of the Lucy Bee coconut oil brand and author of new cookbook Coconut Oil, Nature's Perfect Ingredient, agrees. "I've come to realise that the question is not so much 'What does Fairtrade do?' but more 'Do you know how products are produced if you don't buy Fairtrade?'", she says. "Our products are certified by the Fair Trade Sustainability Alliance and they ensure that those that produce our coconut oil directly benefit. For only a few pence more in cost to us, we can all make a huge difference to the lives of those in our producer communities." It's something worth considering in the supermarket aisle. Or we might find the wheels fall off the coconut bandwagon.