A Dutch anti-doping boss has said the use of ketones within Jumbo-Visma makes him “uncomfortable.”

The chair of the national anti-doping agency in the Netherlands, Herman Ram, said he feels the supplement sits in a “grey area” and advises riders not to use it.

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According to Dutch newspaper De Limburger, Ram said that Sunweb does not use the supplement on advice from the Dopingautoriteit.

Ram said: ‘It’s a legal supplement, but at the same time too little is know about the possible health consequences.

“It’s a grey area. It’s not on the doping list, but if we receive questions from athletes we advise them not to use Ketones.

“Sunweb does not use them for that reason. I find it uncomfortable that Jumbo-Visma does.”

The initial ketone drink was created to fuel soldiers in the US army.

Scientists – Dr. Kieran Clarke of Oxford and Dr. Richard Veech of the National Institute of Health/Defense Advanced Research Projects Agency (DARPA) – were challenged to produce a foodstuff that would provide soldiers with a fuel tailored to success on the battleground.

The formula has since been adopted in sport, with WorldTour cyclists apparently buying into the drinks: which cost as much as $99 (£76) for three 25g bottles and $1149 (£884) for just under a litre.

Adopting a ketogenic diet means training the body to burn fat for fuel, as opposed to carbohydrates.

It’s not a quick fix. The body needs to adapt to the process and the approach divides opinions amongst sports nutritionists quite dramatically.

A study published in Cell Metabolism in 2016 showed that British Cyclists went two to three per cent further in a 30 minute time trial, with consistent improvements present without the need for athletes to adapt to a ketogenic diet to yield results.

However, the results have been questioned. A 2017 study carried out by an Australian research group showed that performance was impaired in trained athletes completing a time trial.

In July, Jumbo-Visma team boss Richard Plugge confirmed his squad used the drink during the Tour de France.

The supplement is not on WADA’s (World Anti-Doping Agency) list of banned substances and is allowed to be used, with riders ingesting it by mixing it into their drinks.

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In November last year, Jumbo-Visma’s Laurens De Plus said he though ketones ‘taste like gin and tonic with a lot of imagination.’

The Jumbo-Visma rider has revealed he is taking the performance boosting supplement, which one study found increases performance by two to three per cent.