Tom Dumoulin discovers cause of stomach issues that led to infamous Giro d'Italia toilet stop

Fructose and lactose caused stomach upset for Dutchman

Tom Dumoulin at the 2018 Abu Dhabi Tour
(Image credit: Yuzuru Sunada)

Tom Dumoulin has discovered the cause of the stomach problems that led to him being forced to answer the call of nature at the side of the road while wearing the pink jersey at last year's Giro d'Italia.

Back in December Dumoulin revealed that he was undergoing tests to work out the cause of the issues that led him to have to stop at the side of the road midway through stage 16 of last year's race, with the results of the tests now in.

Speaking to Dutch broadcaster NOS (opens in new tab), Dumoulin said that the investigation had found that he has trouble digesting high levels of fructose and lactose, a problem that becomes worse when exercising at high intensity.

>>> Tom Dumoulin set to challenge Froome and target both the Giro d'Italia and Tour de France

"A number of food groups, such as fructose and lactose, are not very digestible for some people, and some us have a little more trouble with them than others," Dumoulin said in an interview from an altitude camp in the Sierra Nevada in southern Spain.

"If you are already at the limit in your digestive system and you just eat a piece of food at the wrong time, such as during the Giro, it can come through pretty quickly."

Watch: Giro d'Italia 2018 route guide

Although the tests did not reveal anything seriously wrong with Dumoulin's digestive system, the Dutchman has been testing a diet that is lower in fructose and lactose during recent training sessions, and seems to be adapting well to his new routine.

"On a day where you eat a lot of calories you can eat a lot of lactose and fructose products. In an apple, for example, there is a lot of fructose, so I am better off eating a kiwi."

"Or milk, for example, that is a lot of lactose in. Well, then I better have lactose-free milk or no milk at all."

Dumoulin is currently putting the final touches to his preparations ahead of the Giro d'Italia, where he will head to the Grande Partenza in Israel as the defending champion.

The Dutchman has endured a difficult start to the season as he suffered repeated mechanical problems at the Abu Dhabit Tour - memorably throwing his bike in frustration on the race's final summit finish - before crashing out of Tirreno-Adriatico.

However Dumoulin may take solace in the fact that main rival Chris Froome has also been short on results so far this year, finishing off the pace in the Ruta del Sol and Tirreno-Adriatico, and is travelling to the Tour of the Alps next week for his final preparation.

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Henry Robertshaw began his time at Cycling Weekly working with the tech team, writing reviews, buying guides and appearing in videos advising on how to dress for the seasons. He later moved over to the news team, where his work focused on the professional peloton as well as legislation and provision for cycling. He's since moved his career in a new direction, with a role at the Department for Environment, Food and Rural Affairs.