Meta-analyses of randomized controlled trials (RCTs) have estimated a 13% reduction of
cancer mortality by
vitamin D supplementation among older adults. We evaluated if and to what extent similar effects might be expected from
vitamin D fortification of foods. We reviewed the literature on RCTs assessing the impact of
vitamin D supplementation on
cancer mortality, on increases of
vitamin D levels by either supplementation or food fortification, and on costs of supplementation or fortification. Then, we derived expected effects on total
cancer mortality and related costs and savings from potential implementation of
vitamin D food fortification in Germany and compared the results to those for supplementation. In RCTs with
vitamin D supplementation in average doses of 820-2000 IU per day, serum concentrations of 25-hydroxy-vitamin D increased by 15-30 nmol/L, respectively. Studies on food fortification found increases by 10-42 nmol/L, thus largely in the range of increases previously demonstrated by supplementation. Fortification is estimated to be considerably less expensive than supplementation. It might be similarly effective as supplementation in reducing
cancer mortality and might even achieve such reduction at substantially larger net savings. Although
vitamin D overdoses are unlikely in food fortification programs, implementation should be accompanied by a study monitoring the frequency of potentially occurring adverse effects by overdoses, such as
hypercalcemia. Future studies on effectiveness of
vitamin D supplementation and fortification are warranted.