Every 1000 grams over a birth weight of 3000 grams increases the risk of bowel cancer by nine per cent. Photo Shutterstock Being overweight when very young — even at birth — increases the risk of bowel cancer later in life. This finding comes from research by the Human Nutrition & Health postdoc Moniek van Zutphen. ‘Prevention is more important than ever,’ she concludes.
Van Zutphen studied the link between overweight in childhood and bowel cancer later in life. ‘We already knew that overweight in adults is associated with bowel cancer. Now we wanted to know what the effect is of overweight in earlier phases in life,’ she explains. She looked at research results from previous studies, analysed the relationship for various age categories and got a panel of experts to assess the strength of the evidence.
Twelve per cent more risk
Van Zutphen looked at the weight at birth and the life phases of toddler, child, teenager and young adult (ages 18 to 25). She found a clear linear association between the birth weight and the young adult BMI (weight relative to height) on the one hand and the risk of bowel cancer on the other hand. ‘Every 1000 grams over a birth weight of 3000 grams increases the risk by nine per cent. In young adults with overweight, the risk increases by 12 per cent for every five BMI units above 18.5 kg/m²,’ says Van Zutphen. ‘This confirms the importance of prevention from a young age.’
The Wageningen postdoc carried out the research for the World Cancer Research Fund (WCRF). An international panel from the WCRF, of researchers from countries such as America, Britain, Denmark and the Netherlands, assessed the strength of the evidence of her analyses. ‘They found the evidence very strong.’
Starting point
Associate professor Dieuwertje Kok, who was closely involved in the research, makes a caveat. ‘We see strong associations but we can’t conclude from this data that being overweight when young directly causes bowel cancer. It could be that people who are overweight when young are also more likely to be overweight later in life. Equally, being overweight for long periods may play a role throughout their lives.’ Kok says the results are useful above all as a starting point for further investigations. ‘Perhaps hormones, genes or environmental factors cause both overweight and bowel cancer.’ She emphasizes that having a relatively heavy baby or being overweight at a particular age is not necessarily bad.
Obesity epidemic
Van Zutphen has concerns about the future. ‘We are among the first to study these associations, but our findings are not surprising. Overweight has a negative influence on health in numerous respects.’ She fears the consequences may become even greater due to the increasing prevalence of obesity. ‘The group of bowel cancer patients we studied grew up at a time when fewer people were overweight. The current generation of children may be running even more of a risk.’
