A new meta-analysis suggests that high vitamin D status reduces the risk of lung cancer.
Research has provided evidence that vitamin D protects against cancer through its anti-proliferative effects and regulation of apoptosis, or programmed cell death. Though, there is limited research on the relationship between vitamin D status and lung cancer.
Animal studies have found that vitamin D may inhibit the spread of cancer from the lungs to other organs in the body. There have also been multiple studies that have evaluated the relationship between vitamin D status and lung cancer risk, one of which we covered in a previous blog. However, these results have been inconclusive.
In an effort to clarify the relationship between vitamin D and lung cancer risk, researchers recently conducted a meta-analysis of 12 studies involving a total of 288,778 individuals. The researchers included these studies because they fit the following criteria:
- Cohort studies or nested case-control studies
- Assessed the relationship between vitamin D status and lung cancer risk, or the relationship between vitamin D intake and lung cancer risk.
- The outcomes were lung cancer incidence or mortality.
- Relative risk or data able to calculate risk estimates were available.
Among the 12 studies that were included into the analysis, 9 were prospective cohort studies and 3 were nested case-control studies. Nested case control studies analyzes only a subset of controls from a cohort compared to the incident cases. Three studies evaluated the association between vitamin D intake and lung cancer risk, while nine studies evaluated the association between vitamin D blood status and lung cancer risk.
Here is what the researchers found from their analysis:
- An analysis of all 12 studies showed that those with high vitamin D status had a 16 % decreased risk of developing lung cancer (p < 0.001).
- When looking at the nine studies that assessed the relationship between vitamin D status and risk of lung cancer, the highest vitamin D levels were associated with a 17% reduced risk of developing lung cancer compared to the lowest vitamin D levels (p < 0.001).
- The risk of lung cancer for those with the highest vitamin D intake was reduced by 11% compared to those with the lowest vitamin D intake (p < 0.001).
The researchers concluded,
“Meta-analysis of total 12 studies showed that high vitamin D status was associated with decreased risk of lung cancer.”
The main limitation of this study is that it consisted of prospective cohorts and nested case control studies, therefore, the meta-analysis only proves association. The researchers made an important note that there is still no evidence for the prevention of lung cancer by vitamin D supplementation. Clinical trials are needed in order to evaluate this.
Zhang L., et al. Vitamin D and Lung Cancer Risk: A Comprehensive Review and Meta-Analysis. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology, 2015.