“The sunshine vitamin” (vitamin D) and colorectal cancer survival rates

This study investigated whether colorectal cancer survival rates were influenced by levels of vitamin D in the body.

The rate of occurrence of colorectal cancer (CRC) varies greatly among different populations of the world. This could be due in part to variable levels of vitamin D in the body. Dietary intake of vitamin D is usually low. Most of the body’s vitamin D comes from sunlight. Factors such as geographical location, climate and lifestyle have a major influence on sunlight exposure. Vitamin D levels vary depending on these factors.

Studies have shown that higher vitamin D levels are associated with a lower risk of developing CRC. Interaction between vitamin D levels with certain genetic variants (versions of genes which differ from person to person) has also been shown to influence CRC. However, it is difficult to determine whether vitamin D levels have an effect on CRC outcomes.

This study investigated the relationship between vitamin D levels and CRC survival rates. 1598 patients with stages 1-3 CRC took part. The vitamin D levels of patients were calculated after surgery to remove cancerous tissue. The patients’ gene type (of the genes associated with vitamin D interaction) was determined.  Patients were grouped according to vitamin D levels: group 1 (less than 7.25 ng/mL), group 2 (7.25-13.25 ng/mL) and group 3 (greater than 13.25 ng/mL).  Survival was monitored for up to 9.6 years.

Group 2 patients had a 14% lower chance of dying due to CRC and a 19% lower chance of death due to any cause in comparison to group 1 patients. Group 3 patients had a 32% lower chance of dying due to CRC and a 30% lower chance of death due to any cause in comparison to group 1 patients.

The effect was greatest in stage 2 patients. Stage 2 patients in group 3 had a 56% lower chance of dying due to CRC, than group 1 patients.

The protective effect of vitamin D levels was stronger in patients who were not receiving chemotherapy. Certain genetic variants were also associated with a protective effect.

The authors concluded that higher vitamin D levels are associated with longer survival from CRC, especially for stage 2 patients. 

This study did not examine the use of vitamin D supplements. The impact of vitamin D supplementation in CRC patients will reveal more information on the meaning of these findings for patients.

Consult your doctor if you have CRC and you are concerned about your vitamin D levels.