Disclaimer: This article provides general information and is not a substitute for professional medical advice. Before making medical decisions, consult a qualified healthcare professional with any health concerns or questions.
Bowel cancer is one of Australia’s most common cancers. While we’re all familiar with the usual advice—eat your veggies, get moving, and don’t skip your screenings—a leading cancer expert has revealed there may be a straightforward supplement that could help tip the odds in your favour.
Professor Justin Stebbing, a renowned biomedical scientist at Anglia Ruskin University, has weighed in on the growing research linking vitamin D to bowel cancer risk.
According to Stebbing, while vitamin D isn’t a miracle cure, there’s enough promising evidence to suggest that maintaining healthy levels could play a role in reducing your risk of developing bowel cancer.
‘Maintaining sufficient vitamin D levels—at least 30 ng/ml—is a low-risk, cost-effective health measure,’ he wrote.
‘Combined with other strategies like regular screening, a healthy diet, physical activity, and personalised care, vitamin D could still play a valuable role in overall cancer prevention.’
Vitamin D, often called the ‘sunshine vitamin’, is produced in our skin when exposed to sunlight. It’s also found in oily fish (salmon, sardines, and mackerel), red meat, liver, and egg yolks.
For many Australians, especially during the cooler months or those who spend much time indoors, supplements are a popular way to top up levels.
Vitamin D is crucial for strong bones, healthy teeth, and a robust immune system. But what about cancer?
Laboratory studies have shown that vitamin D can help regulate cell growth, reduce inflammation, and support the immune system—all factors that could, in theory, help prevent cancer cells from taking hold, particularly in the bowel.
Some studies have found that people with higher vitamin D levels are less likely to develop bowel cancer. For example, observational research has suggested a link between adequate vitamin D and a lower disease risk.
However, the results are less clear when it comes to the gold standard of medical research—randomised controlled trials.
One major study involving 25,000 participants found that vitamin D supplements did not significantly reduce the risk of developing bowel cancer.
On the other hand, another study found that people who already had bowel cancer and took vitamin D supplements lived longer than those who didn’t.
So, what’s going on? Stebbing suggested it could be that only certain people benefit, or that the correct dose is key. There’s also debate about whether low vitamin D causes cancer, or if developing cancer leads to lower vitamin D levels.
The bottom line? The evidence isn’t strong enough to recommend vitamin D supplements as a guaranteed way to prevent bowel cancer.
However, because vitamin D is vital for so many aspects of health, and deficiency is surprisingly common, especially in winter, ensuring you get enough is still a smart move.
One worrying trend is the rise in bowel cancer among younger adults. While the overall risk remains much higher in people over 50, cases in those aged 25-49 have increased by more than 50% in recent decades.
The reasons aren’t fully understood, but possible culprits include changes in diet (more ultra-processed foods), sedentary lifestyles, and even environmental factors.
In Australia, it’s estimated that up to one in four adults may have low vitamin D levels during the cooler months. The best way to know your status is with a simple blood test from your doctor.
If you’re considering a supplement, the general advice is not to exceed 100 micrograms (4000 IU) per day unless your doctor recommends it. Too much vitamin D can cause problems, including kidney and heart issues.
While vitamin D might play a supporting role, there are several well-established steps you can take to lower your risk of bowel cancer:
- Get screened: Regular bowel cancer screening is one of the most effective ways to catch the disease early, when it’s most treatable. Australians aged 50-74 are eligible for free home test kits through the National Bowel Cancer Screening Program every two years.
- Eat a healthy diet: Focus on plenty of fibre from whole grains, fruits, and vegetables. Limit red and processed meats, which have been linked to higher bowel cancer risk.
- Stay active: Aim for at least 30 minutes of moderate physical activity most days of the week.
- Maintain a healthy weight: Being overweight or obese increases your risk.
- Limit alcohol and don’t smoke: Both are known risk factors for bowel and other cancers.
Have you had your vitamin D levels checked lately? Do you take supplements, or have you made other changes to reduce your cancer risk? Share your experiences and tips in the comments below.
Also read: Could your favourite ‘health food’ be raising your cancer risk? Here’s what doctors say
