New findings indicate that an increased intake of vitamin D may help to prevent the development of early-onset colorectal cancer in individuals under the age of 50.
Increased intake of vitamin D coupled with screenings could potentially add to the current colorectal cancer (CRC) prevention strategy in adults who are under the age of 50, according to the results of study published in Gastroenterology.1
Investigators reported that higher total vitamin D intake was significantly associated with a reduction in the risk of developing early-onset CRC (HR, 0.49; 95% CI, 0.26-0.93; P = .01). It was noted that a significant inverse association was identified and was more evident for dietary sources of vitamin D (HR, 0.34; 95% CI, 0.15-0.79) vs supplemental vitamin D (HR, 0.77; 95% CI, 0.37-1.62). Moreover, the odds ratios (ORs) for CRC precursors per 400 IU per day were reported for conventional adenoma (n = 1439; OR, 0.76; 95% CI, 0.65-0.88) and serrated polyp (n = 1878; OR, 0.85; 95% CI, 0.75-0.97).
“Vitamin D has known activity against colorectal cancer in laboratory studies. Because vitamin D deficiency has been steadily increasing over the past few years, we wondered whether this could be contributing to the rising rates of colorectal cancer in young individuals,” Kimmie Ng, MD, MPH, director of the Young-Onset Colorectal Cancer Center at Dana-Farber Cancer Institute, said in a press release.2 “We found that total vitamin D intake of 300 IU per day or more—roughly equivalent to three 8-oz. glasses of milk – was associated with an approximately 50% lower risk of developing young-onset colorectal cancer.”
Investigators analyzed data from the Nurses’ Health Study II, a prospective cohort study that included 116,429 female nurses between the ages of 25 to 42 years old, spanning back to 1989. Those who were included in the study were followed every 2 years through self-administered questionnaires on their demographics, lifestyle factors, and medical information in addition to dietary intake assessments every 4 years. In the analysis of this study, investigators excluded patients with inflammatory bowel disease or those who had previously been diagnosed with CRC.
Among the 94,205 women who were included in the analysis, 111 incidents of early-onset CRC were reported from 1991 through 2015. The median vitamin D intake was 372 IU per day. Those who were under the age of 50 who had a higher vitamin D intake also had a lower body mass index and were less likely to smoke cigarettes, drink alcohol, spend time watching TV, and eat red or processed meat. This group was also more likely to eat dietary fiber, consume folate and total calcium, use aspirin and multivitamins, and be physically active with a healthy dietary pattern.
When compared with women who consumed less than 300 IU per day of total vitamin D, age and multivariable adjusted analyses indicated a reduced risk of early-onset CRC in women who consumed between 300 and less than 450 IU per day (HR, 0.51; 95% CI, 0.30-0.86; P = .01) as well as in those consuming over 450 IU per day (0.49; 95% CI, 0.26-0.93; P = .01)
A higher intake of vitamin D was also associated with a lower risk of early-onset conventional adenoma and suggestively associated with serrated polyp. In this regard, a difference in multivariable-adjusted OR of any conventional adenoma of 0.71 was noted (95% CI, 0.56-0.89) for those who consumed 600 IU or more per day of total vitamin D vs less than 300 IU per day (P = .002). Additionally, using the same comparison for any serrated polyp, investigators reported an OR of 0.85 (95% CI, 0.70-1.03; P = .11).
Additional findings indicated that there was an association between continuous vitamin D intake and CRC risk that varies based on age of diagnosis, including those under 50 years and those who were 50 years or older (P = .04). Although investigators found that vitamin D intake had an association with the risk of developing early-onset CRC, a statistically significant association with the risk of CRC diagnosed in patients aged 50 year or older could not be detected, potentially due to limited power.
“We found evidence that higher total vitamin D intake is associated with decreased risks of early-onset CRC and precursors. Our results further support that avoiding low vitamin D status is important in younger adults for health and possibly CRC prevention. If confirmed, our findings could potentially lead to recommendations for higher vitamin D intake as an inexpensive low-risk complement to CRC screening as CRC prevention strategy for adults younger than age 50,” the authors of the study concluded.