Vitamin D deficiency as a public health issue: using vitamin D₂or vitamin D₃in future fortification strategies

Abstract

The role of vitamin D in supporting the growth and maintenance of the skeleton is robust; with recent research also suggesting a beneficial link between vitamin D and other non-skeletal health outcomes, including immune function, cardiovascular health and cancer. Despite this, vitamin D deficiency remains a global public health issue, with a renewed focus in the UK following the publication of Public Health England's new Dietary Vitamin D Requirements. Natural sources of vitamin D (dietary and UVB exposure) are limited, and thus mechanisms are needed to allow individuals to achieve the new dietary recommendations. Mandatory or voluntary vitamin D food fortification may be one of the mechanisms to increase dietary vitamin D intakes and subsequently improve vitamin D status. However, for the food industry and public to make informed decisions, clarity is needed as to whether vitamins D2 and D3 are equally effective at raising total 25-hydroxyvitamin D (25(OH)D) concentrations as the evidence thus far is inconsistent. This review summarises the evidence to date behind the comparative efficacy of vitamins D2 and D3 at raising 25(OH)D concentrations, and the potential role of vitamin D food fortification as a public health policy to support attainment of dietary recommendations in the UK. The comparative efficacy of vitamins D2 and D3 has been investigated in several intervention trials, with most indicating that vitamin D3 is more effective at raising 25(OH)D concentrations. However, flaws in study designs (predominantly under powering) mean there remains a need for a large, robust randomised-controlled trial to provide conclusive evidence, which the future publication of the D2-D3 Study should provide (BBSRC DRINC funded: BB/I006192/1). This review also highlights outstanding questions and gaps in the research that need to be addressed to ensure the most efficacious and safe vitamin D food fortification practices are put in place. This further research, alongside cost, availability and ethical considerations (vitamin D3 is not suitable for vegans), will be instrumental in supporting government, decision-makers, industry and consumers in making informed choices about potential future vitamin D policy and practice.

Vitamin D2 vs. vitamin D3: They are not one and the same

“…Considering the limited number of natural sources of vitamin D, food fortification and supplementation have been highlighted as potential strategies for increasing intakes of vitamin D and subsequently improving vitamin D status (Buttriss ; Wilson et al . ). However, whether vitamin D 2 or vitamin D 3 should be used as the primary source needs to be better understood in order to inform key stakeholders involved in driving forward public health policy and its implementation.…”

“…Although several intervention trials have been conducted since the 2012 meta‐analysis, as discussed in a review by Wilson et al . (), findings remain equivocal and underpowered sample sizes remain an issue.…”

Food fortification and biofortification as potential strategies for prevention of vitamin D deficiency

“…More recently, a review by Wilson et al . () summarised the evidence to date on the relative effectiveness of vitamin D 3 and vitamin D 2 at raising 25(OH)D concentrations and concluded that most RCTs show vitamin D 3 to be more effective.…”

“…Data were included from seven RCTs, and the results showed that vitamin D 3 intake led to a greater absolute change in serum/plasma 25(OH)D levels from baseline than intake of vitamin D 2 , with a weighted mean difference of 15.23 [95% confidence interval (CI): 6.12, 24.34; Z = 3.28; I 2 = 81%; P = 0.001]. More recently, a review by Wilson et al (2017) summarised the evidence to date on the relative effectiveness of vitamin D 3 and vitamin D 2 at raising 25(OH)D concentrations and concluded that most RCTs show vitamin D 3 to be more effective.…”

Vitamin D-biofortified beef: A comparison of cholecalciferol with synthetic versus UVB-mushroom-derived ergosterol as feed source

“…Recent estimates from national surveys in Europe indicate that as much as 55 and 100% of adults (19-64 years) and older adults (> 64 years) have inadequate vitamin D intakes when compared to the Estimated Average Requirement (EAR) (Roman Viñas et al, 2011). Consequently, there is a definite need for innovatively designed natural food-based vitamin D-enhancement strategies which cover a range of stable food sources reflective of diversity in dietary patterns and fortification policies (Black, Seamans, Cashman and Kiely, 2012;Guo, Kliem, Lovergrove and Givens, 2017;Verkaik-Kloosterman, Seves and Ocké, 2017;Wilson, Tripkovic, Hart and Lanham-New, 2017).…”