A glass of juice in the morning is believed to be the healthy way to start a day, but Australian scientists have claimed that some fruit juices contain so much sugar that they actually increase the risk of certain cancers, rather than preventing them.
They said, in fact, by the time the drink has been processed and packaged, many of the ingredients in fruit that protect against tumours have been lost, the Daily Mail reported.
The researchers wanted to establish how effective different fruits, vegetables and juices were at preventing the development of bowel cancer.
They examined the diets of 2,200 adults, who filled in a questionnaire detailing their daily eating habits. The team then tracked the participants for two years to see how many of them developed the disease.
Unsurprisingly they found that eating apples, sprouts, cauliflower or broccoli on a daily basis all reduced the likelihood.
However, those who consumed lots of fruit juice had a higher risk.
The research found that those drinking more than three glasses a day were more likely to develop rectal cancer, a form of bowel cancer.
Scientists believe the high sugar content in juice may trigger certain tumours.
The Perth team also said that many things found in fruit which help protect against bowel cancer - including fibre, vitamin C and chemicals known as antioxidants - are lost during the juice's processing.
The findings were published in the journal of the American Dietetic Association.