New research published in the British Medical Journal has confirmed that vitamin D has protective effects against numerous site-specific cancers in both men and women.
The findings of this large population-based cohort study from Japan found that the higher the concentration of vitamin D the lower the risk of total cancer.
“Although the beneficial effects of vitamin D in the prevention of skeletal disorders have long been recognised, accumulating evidence suggests that the benefits may extend beyond bone health to include several chronic diseases, including cancer.”
“Given that vitamin D concentrations and metabolism vary substantially by race/ethnicity we designed a case-cohort study that measured plasma 25-hydroxyvitamin D Concentration in the largest number of cancer cases to date (n=3301) within a Japanese population of the Japan Public Health Center-based Prospective(JPHC) Study,” the authors stated.
The study measured plasma 25-hydroxyvitamin D in the largest number of cancer cases to date, and observed that a higher circulating concentration of vitamin D was associated with a lower risk of total cancer even after adjustment for known risk factors for cancer and across a variety of sensitivity analyses.
“A notable finding of our study is that, compared with the lowest quarter of 25-hydroxyvitamin D concentration, the hazard ratio for total cancer decreased progressively in the second and third quarters but did not further decrease in the highest quarter. When we repeated the analysis in quintile-based categories, we observed a similar decreasing pattern in risk estimates, with the smallest hazard ratios in the third and fourth fifths, suggesting a potential ceiling effect,” the authors reported.
This ceiling effect observed in the study may suggest that no additional benefit would result after a certain concentration of 25-hydroxyvitamin D is exceeded. The authors suggest that this together with the findings of previous trials, indicate that raising a low 25-hydroxyvitamin D concentration to an intermediate concentration may provide protection, where as raising it to a higher concentration (probably above around 80 nmol/L) may provide no further benefit.
“To our knowledge, this is the first report involving circulating 25-hydroxyvitamin D concentrations and risk of total cancer in an Asian population.The lower risk associated with higher circulating vitamin D concentration seemed to show a ceiling effect, which may suggest that although maintaining an optimal 25-hydroxyvitamin D concentration is important for prevention of cancer, having a concentration beyond this optimal level may provide no further benefit. Future studies are needed to clarify the dose-response pattern and the optimal concentrations for cancer prevention,” the authors concluded.
Source:  BMJ 2018;360:k671 (Published 07 March 2018)
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