In the forests of Perthshire a 5,000 year old tradition is being recreated with birch trees being tapped for the health-giving sap contained within the ancient trees.

For the first time, a commercial operation has begun in Scotland to take and bottle the “birch water” and sell it to the public.

Gabrielle and Rob Clamp use maple syrup kits bought from Canada to syphon off the natural tonic which is reputed to cleanse kidneys and liver, ease arthritis and rheumatism, and help strengthen teeth.

The process is popular in Finland and the Baltic countries and the water is drunk by celebrities including Victoria’s Secret model Rosie Huntington-Whiteley. But it has never been seen here on a large scale.

However, there is a history of birch water in Scotland going back millennia. Rob, whose company Birken Tree collects around 5,000 litres of sap each year, says: “We trace it back at least 5,000 years. There was a Neolithic lady whose body was dug up in Caithness where I am from and there was evidence of some food and some of that was birch sap. In the Highlands there are records of people using it as a tonic after a long winter; giving it to babies, themselves and even cattle. It makes sense because it is so full of minerals and vitamins and it is a lean period (in nature).”

Although still known about in other countries Rob says there could be a simple reason its use died out here. “They have a very different history to us in Scotland. People were cleared away to the New World and that connection to the land was severed.”

Sat amid the birch trees of Grandtully Forest in Perthshire, Rob explains the unique taste: “I like the silkiness of it, almost creamy. There is a very slight sweetness, depending on the tree or the season. Some people compare it to melons or cucumber, it is very subtle.”

When they first tapped the sap last year Gabrielle said she was “excited”: “We realised the taste of fresh sap was different from the bottle we had before – we really loved it. That is why we use glass bottles to keep the taste right. And, if you warm it up slightly the flavours are more intense.”

There is usually only a three week window to gather the sap in spring because as the warmer months arrive it develops a bitter taste.

However, the season has been is longer this year though because the warmer weather in February meant they started in the second week of March.

They collect about 5,000 litres a year but estimate that each tree only loses a tiny amount of its sap. Rob says: “We take about one per cent. We know they take up 100s of litres a day and we take about five.”

Gabrielle gave up a job as a chiropractor to concentrate on the business. And while Rob still works as a forester he aims to concentrate on their start up business full-time.

Internationally, the market is worth millions of dollars and Gabrielle and Rob were introduced to it when a friend gave them a bottle marked “Made in Finland”.

Gabrielle says: “We thought someone must make it in Scotland but no.” As a result, they became the only Scottish producers on a commercial level, selling to local delicatessens and through a wholefood distributor.

Gabrielle adds: “There are lots of vitamins and minerals, enzymes and amino acids. There is xylitol as well which is good for the teeth.

“A lot of people ask if it is (normal) water because it is called birch water but no, it is pure sap.”

The sap ferments in three days so they freeze it and then pasteurise it a little to give it a longer shelf life.

Rob says: “At some point it would be nice to focus on it full time and we have launched a crowdfunding campaign.” Growing the business will mean adding flavours such as cranberry, bilberry and meadowsweet and also creating sparkling birch water which has been asked for by high end hotels and restaurants.

Rosie Huntington-Whiteley, 31, has written about birch water on her Facebook page saying the “nutrient-dense liquid” is a “hero ingredient”.

Despite the trendy, modern feel to the product Rob insists its 5,000 year history means what they are doing is “nothing new”. He adds: “What we are saying is ‘hello, you should be drinking this stuff’.”

Hayley Bruce, Commercial Marketing Intelligence Manager at Scotland Food & Drink, said: “Scotland has a rich heritage when it comes to food and drink production and it is great to see traditional techniques being adopted in the modern world. Searching through the past for inspiration, whether looking for ancient wisdoms, indigenous ingredients or heritage produce, can open up some fantastic new opportunities for the Scottish food and drink sector.”