Study under review: The effect of vitamin D supplementation on survival in patients with colorectal cancer: systematic review and meta-analysis of randomised controlled trials
Colorectal cancer affects up to 1.8 million people each year and it is responsible for roughly 850,000 deaths worldwide. There appears to be at least some environmental components to colorectal cancers, as there are major differences in incidence rates based on geographical locations and socioeconomic strata. One hypothesis for the substantial differences in incidence rates is that vitamin D may play a role in the development and progress of several cancers, including colorectal cancers.
There is data linking vitamin D to colorectal cancer. For example, an observational study found that there is an inverse correlation between colorectal cancer incidence rates and sunlight exposure by geographical location. Mechanistically, cultured colon cancer cells divide at a slower rate when treated with vitamin D, compared to when they’re untreated. However, not all research has produced supporting evidence. For example, a Mendelian randomization study did not show a clear causal impact of blood 25-hydroxyvitamin D level on CRC risk. Furthermore, several studies have reported that supplementation with vitamin D does not reduce the risk of developing cancer, including colorectal cancer. In addition to prevention, there have been several randomized trials examining the effect of vitamin D supplementation on the progression of already established colorectal cancer. The present study was systematic review and meta-analysis of randomized controlled trials examining the effect of vitamin D supplementation not on incidence of colorectal cancer, but on the survival and progression of disease in participants who had already developed it.
Vitamin D has been linked to colorectal cancer through observational and mechanistic research. Recently, several randomized trials have investigated the role of vitamin D supplementation on slowing disease progression and improving survival among people with colorectal cancer. The present study was a systematic review and meta-analysis of randomized controlled trials examining the effect of vitamin D supplementation on disease progression and survival among people with colorectal cancer.
Other Articles in Issue #73 (November 2020)
News: The gut microbiome probably plays a significant role in type 1 diabetes
Recent research provides substantial evidence that gut microbiota can play a big part in new-onset type 1 diabetes.
Can switching from meat to plant-based meat alternatives reduce cardiovascular disease risk?
This study found that replacing meat with Beyond Meat lowers both TMAO and LDL-C.
Deep Dive: Does beta-alanine improve training performance?
If there are any effects present, they're mostly small. But small effects can still be worthwhile for some competitive athletes.
Probiotics for celiac disease
The current evidence is promising but should be seen as preliminary and weak. A lot more research needs to be done to see which probiotics, if any, work well for celiac disease.
Nulls: September-October 2020
Know new nulls now!
Is honey an effective remedy for symptoms of upper respiratory tract infections?
This meta-analysis hints at a small-to-moderate effect, but the overall quality of the evidence ain't great.
Deep Dive: Reducing common vertigo with vitamin D and calcium
This large, long trial found a pretty strong effect of supplementation on benign paroxysmal positional vertigo recurrence. But there are some problems beneath the surface of these promising findings.