Colorectal cancer is one of the most common forms of cancer around the world. Though the overall incidence has declined over time, the number of cases in younger people has increased.
Approximately 50 percent of people with the condition do not have genetic risk factors or family history. Therefore, diet or lifestyle changes may help reduce the incidence.
A recent study published in the Gastroenterology journal suggested that vitamin D may help protect against this form of cancer. Reduced consumption of eggs, mushrooms, fish, dairy products, and other vitamin D-rich foods may increase the risk of developing the condition.
The project was carried out by a group of scientists at the Harvard T.H. Chan School of Public Health.
They analyzed data on the medical history, lifestyle, and diet of more than 116,000 female nurses between 25 and 42 years old. The data was collected since 1989.
All participants had to fill out a questionnaire every two years about their medical, lifestyle, and health-related information. Similarly, they needed to answer detailed questions about their diet every four years.
The authors analyzed collected data to measure total intakes of vitamin D from their supplements and diet.
There were 111 diagnosed cases of colorectal cancer from 1991 to 2015 among participants.
After adjusting other risks, such as sedentary lifestyle, red meat consumption, alcohol consumption, and smoking, scientists found that vitamin D consumption was significantly linked to a lower risk of colorectal cancer.
The effect seemed to be greater for vitamin D coming from dietary sources than supplements, especially dairy products.
The study found a link between low intake of vitamin D and disease precursors, including polyps and adenomas.
Taking in around 300 IU of vitamin D per day would decrease the risk of colorectal cancer up to 50 percent.
The findings would lead to recommendations for a higher intake of vitamin D as a low-risk and inexpensive method to prevent colorectal cancer in young adults.
However, the scientists highlighted that they do not fully understand how the underlying mechanism works.
This study and other similar research may help us understand better the role of diet and vitamin D in the increased rate of colorectal cancer in young adults. However, more studies are needed to draw the final conclusion.
The author concluded that studies with larger sample sizes should be done to confirm these results.
Another drawback is the quite small number of cancer cases, which limited statistical power. Also, all participants in the study were mostly white females. This means the finds might not apply to non-white people and men.