Diet of pregnant women can influence whether their children will develop early-age bowel cancer, experts claim – after bombshell study finds that overweight babies could be behind mystery rise in under-50s
Women who gain too much weight during pregnancy could be condemning their child to an increased risk of early onset bowel cancer decades later, experts warn.
‘We know that some early life exposures – including maternal obesity and excessive weight gain during pregnancy – may increase the risk of early onset colorectal cancer,’ Dr Rosiered Brownson-Smith, an expert in the risks associated with diet, lifestyle and health, at King’s College London, said.
‘This can change the trajectory of a child’s life, potentially predisposing them to some early susceptibility that will only come to fruition later in life.’
Her remarks follow a sharp rise in the number of young people diagnosed with the disease, with more than 2,700 cases among young people every year in the UK.
It has long been suggested that a mother’s health profile can have a lasting effect on their offspring’s health. But experts have suggested that later life exposures, such as smoking, are more important when it comes to cancer risk.
However, according to Dr Brownson-Smith, we cannot afford to overlook these additional risk factors that could predispose young people to developing the disease.
‘There are always things that young people can do to offset their risk, which may be more important if they have one of these additional risk factors – such as being delivered by caesarean and maternal obesity or weight gain,’ she explains.
‘Staying active, reducing alcohol consumption, limiting ultra-processed foods, not smoking and increasing fibre intake can all reduce the risk of early onset bowel cancer – and may be especially important for people at higher risk.’
More than 2,700 cases of bowel cancer are diagnosed in young people annually in the UK
In humans, maternal obesity during pregnancy is associated with more than double the colorectal cancer risk in offspring, potentially via two pathways.
Firstly, children of obese mothers are more likely to develop obesity – an independent risk factor that has been linked to a five-fold increase in bowel cancer risk.
Maternal weight can also exert a direct effect on a baby’s developing gastrointestinal tract in the womb, making them more susceptible to lifestyle triggers.
‘When cancer occurs, it’s not just caused by one event,’ Dr Brownson-Smith explains.
‘Rather it’s the culmination of lots of mutations that build up slowly over time. Some of these mutations may have no effect, while others build towards what we know as cancer.
‘These early imprints could represent some of the first biological changes that increase risk, preparing gut cells to mutate more readily, and sending us further down the road to precancerous lesions or full blown cancer.’
Birth weight is also thought to influence risk, with overweight mothers more likely to give birth to bigger babies.
According to a new study published by the Yale School of Public Health, girls who weighed an additional half a kilogram at birth faced a 10 per cent higher risk of developing early-onset colorectal cancer.
While experts are not entirely sure why this is the case, the current theory is that birth size reflects the intrauterine environment, which may programme long-term metabolic changes that influence cancer risk.
Previous studies have suggested that excess weight can disrupt the production of growth hormones needed during pregnancy, potentially impacting the health of children later in life.
Experts say this might help explain why the disease is on the rise in an age group that ‘simply shouldn’t be getting cancer’.
‘While we are unlikely to find one smoking gun, there is some evidence that this early life imprinting may be contributing to the increase of young bowel cancers,’ Dr Brownson-Smith said.
‘There is something in the way we are living our lives today – including our reliance on ultra processed foods and increasingly sedentary lifestyles – which means that young people are more at risk of developing the disease.
‘And given that we are seeing lots of young people diagnosed with the disease who don’t have traditional risk factors – like smoking, drinking and obesity – it suggests there must be some early life exposure contributing to their risk.’
Obesity is one of the single biggest factors for rising bowel cancer rates among young people, research increasingly shows.
It’s the only known behavioural risk factor that has increased in younger adults – many of whom are of reproductive age – over the past two decades, while other recognised risk factors such as alcohol and physical inactivity have all remained stable or improved.
Maintaining a healthy weight could prevent around 20 per cent of cases, with experts urging people to up their fibre intake alongside physical activity to reduce the risk of the disease.
Despite obesity being identified as a key factor behind the rising bowel cancer rates among younger adults, researchers say it’s not sufficient to explain the overall rise, indicating that other factors — including early-life exposures — may also play a role.
