More Vitamin D Could Lower Colorectal Cancer Risk in Women

In the United States, colorectal cancer is the third leading cause of cancer-related deaths in men and in women. Deaths from colorectal cancer in people younger than 55 have increased by 1% per year from 2008 to 2017.

According to a new study published in the journal Gastroenterology, a diet rich in vitamin D is linked to a near 50% reduced risk of developing colorectal cancer or precancerous colon polyps in young women.

Tamar Samuels, MS, RD, a registered dietitian and the co-founder of Culina Health, tells Verywell that the new study "looked at the relationship between vitamin D status and early-onset colorectal cancer among women enrolled in the Nurses Health II study,” and "found that participants with higher intakes of vitamin D had a lower risk of early-onset colorectal cancer.”

Vitamin D May Reduce Colorectal Cancer Risk

Past research has shown a link between a healthy vitamin D status and a reduced risk of colorectal cancer (CRC). However, data on younger populations is lacking. Additionally, a large amount of the available data highlights the positive relationship between a sufficient vitamin D status, and not necessarily the dietary intake of the nutrient.

Using data from over 90,000 women subjects enrolled in the Nurses’ Health Study II, researchers at the Harvard T.H. Chan School of Public Health and other institutions analyzed the diets, lifestyles, and medical histories of female nurses aged 25 to 42 years old. 

The researchers evaluated whether there was an association between total vitamin D intake and risks of early-onset CRC and precursors. 

The Results

The results of the study showed that a higher total vitamin D intake was significantly associated with a reduced risk of early-onset CRC—especially when comparing those who took in at least 450 IU compared to those who took in less than 300 IU per day.

Ultimately, taking in at least 300 IU of vitamin D per day resulted in almost a 50% reduced risk of CRC among women aged 50 and younger. 

The findings indicated that getting vitamin D from food sources rather than supplements appeared to offer a greater benefit. The study did not find a significant association between the quantity of vitamin D intake and the risk of CRC after the age of 50.

Limitations

“While this study has its limitations, it does give us insight into the role of vitamin D in cancer prevention,” says Samuels. “Specifically, it seems that vitamin D from food sources may be more beneficial to colorectal cancer prevention compared to supplemental vitamin D.”

Some limitations the study possesses that Samuels highlights include:

• It was an observational study, which means a cause and effect relationship cannot be assumed
• It exclusively looked at women and therefore the results cannot be extrapolated to other populations
• The food measured in the study was done via self-reporting, which can be unreliable

Reducing Your CRC Risk Through Diet

Vitamin D is a fat-soluble vitamin that can be synthesized by the human body. When the skin is exposed to sunlight, the body can produce vitamin D naturally. 

Getting 20 minutes of sunshine daily with over 40% of skin exposed is required to prevent vitamin D deficiency. The vitamin can also be obtained through food or supplements. 

“Including foods such as mushrooms, eggs, cheese, milk, fortified cereals, and oily fish such as salmon, mackerel, and tuna can help people increase their vitamin D intake,” Nichole Giller, RD, LD, CSO, an oncology dietitian at the George Washington Hospital in Washington, D.C. tells Verywell. “Getting in enough Vitamin D has so many benefits already such as helping to keep strong bones, support the immune system to function its best, and fight off invading bacteria and viruses.” 

Making a conscious effort to eat more vitamin D-containing foods can help prevent deficiency, and for women under the age of 50, it could potentially help reduce CRC risk. 

Vitamin D-Rich Foods

While certain factors that increase your risk of developing CRC are out of your control (such as genetics and age) other factors are modifiable. Some lifestyle choices that may reduce your CRC risk include:

• Maintaining a healthy weight
• Living an active lifestyle
• Limiting large quantities of processed meats
• Avoiding cigarette smoking and moderate or heavy alcohol use

According to the current study, for people who are aged 50 years old or younger, eating at least 300 IU of vitamin D every day can be a positive addition to your diet when trying to reduce CRC risk too.  

Some food combinations that contain at least 300 IU vitamin D include:

• 2 glasses of dairy milk, one egg, and 1.5 ounces of cheddar cheese
• 3 ounces of salmon
• ½ cup of mushrooms that were exposed to UV light
• 3.5 ounces canned tuna and a glass of vitamin D-fortified 100% orange juice