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Dumoulin identifies fructose and lactose as cause of Giro d'Italia digestive problems

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Tom Dumoulin at the Giro d'Italia's stage 16 finish line

Tom Dumoulin at the Giro d'Italia's stage 16 finish line
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Tom Dumoulin (Team Sunweb) waits for a question at the Tirreno-Adriatico press conference

Tom Dumoulin (Team Sunweb) waits for a question at the Tirreno-Adriatico press conference
(Image credit: Tim de Waele/TDWSport.com)
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Tom Dumoulin (Team Sunweb) sign on

Tom Dumoulin (Team Sunweb) sign on
(Image credit: LaPresse - Ferrari / Paolone)
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Tom Dumoulin (Sunweb) in his rainbow jersey

Tom Dumoulin (Sunweb) in his rainbow jersey
(Image credit: Team Sunweb)
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Tom Dumoulin (Team Sunweb) was asked about his 2017 Giro d'Italia victory

Tom Dumoulin (Team Sunweb) was asked about his 2017 Giro d'Italia victory
(Image credit: Tim de Waele/TDWSport.com)

The image of Tom Dumoulin, in the maglia rosa, pulling over for an emergency toilet break ahead of the Stelvio will stand the test of time in Giro d'Italia legend, but the Dutchman is understandably doing everything he can to ensure the scenario doesn't repeat itself, and he thinks he's found the answer.

Dumoulin, who went on to win the 2017 Giro d'Italia despite his mishap, has been carefully studying his nutrition and digestive system to try to understand the cause of the problem, which has presented itself elsewhere, albeit less dramatically.

The Team Sunweb rider spent two days in hospital conducting research at the end of last year, ruling out bacteria or viruses in the gut, and he has since followed a diet to figure out which food types might be responsible.

Currently laying the foundations for another tilt at the Giro with a spell of altitude training in Sierra Nevada, Dumoulin told Dutch broadcaster NOS that he has a slight aversion to fructose and lactose, two types of sugar.

"A number of food groups, such as fructose and lactose, are not very digestible for every human being," he said. "Some people have a little more trouble with it than others. Me, well I probably have a little more trouble."

Dumoulin explained that the problem occurs only on long, hard days on the bike, where the body is pushed to exertion and thousands of calories worth of food need to be taken in.

"If you are already on the limit in terms of digestion in your digestive system, and you just throw something in at the wrong time, such as during the Giro, it can be passed through directly," he said. 

"On a day of high caloric intake, you can get a lot of lactose and fructose products in. In an apple, for example, there is a lot of fructose, so I better eat a kiwi," he joked. "Or milk, for example, there is a lot of lactose in. Well, then I better take lactose-free milk or no milk at all."

After a miserable start to the 2018 season, Dumoulin is currently training in Sierra Nevada, and his only scheduled racing appearance ahead of the Giro is Liège-Bastogne-Liège a week on Sunday.

The Giro begins in Jerusalem on May 4 and ends in Rome on May 27.