According to a large study of Japanese adult participants, there may be a correlation between high amounts of vitamin D and a reduction in the risk of developing cancer.
Previously, similar studies have been done on Caucasians in America and Europe. However, as vitamin D concentrations differ based on ethnicity, the researchers sought to discover vitamin D’s effects on non-Caucasian populations.
The researchers’ goal was to determine if there was an association between vitamin D and either the risk of total cancer, or site-specific cancer.
First, the researchers began evaluating data from the Japan Public Health Center-based Prospective (JPHC) Study. The study involves data from over 33,000 Japanese participants, ages 40 – 69 years.
The study’s data also includes each participants’ medical history, blood samples, and information about their lifestyle and diet. The season was also taken into account, seeing as as vitamin D levels tend to be higher in summer and autumn than in winter and spring.
The samples were split into four groups, ranging from the lowest levels of vitamin C to the highest. Then, the participants went under close monitoring for an average of 16 years – during which the development over 3,000 new cases of cancer occurred.
According to Science Daily:
After adjusting for several known cancer risk factors, such as age, weight (BMI), physical activity levels, smoking, alcohol intake and dietary factors, the researchers found that a higher level of vitamin D was associated with a lower (around 20%) relative risk of overall cancer in both men and women.
Higher vitamin D levels were also associated with a lower (30-50%) relative risk of liver cancer, and the association was more evident in men than in women.
No association was found for lung or prostate cancer, and the authors note that none of the cancers examined showed an increased risk associated with higher vitamin D levels.
Further studies are necessary in order to discover what the optimal concentrations of vitamin D are for cancer prevention. However, these results are certainly a step in the right direction.