Lipid-modifying effect of vitamin D fortified products: A systematic review and meta-analysis of Randomized Controlled Trials

Various fortification strategies have been proposed to account to treat or prevent vitamin D deficiency. However, the optimum fortification approach, and the effect of these on health is not widely understood. There have been controversial reports regarding the effect of vitamin D fortification on the lipid profile. The aim of present review is the evaluation of administration of vitamin D fortified products on lipid profile. We used databases including PubMed/Medline, ISI Web of Knowledge, Science Direct, Scopus and Cochrane Library. A search was conducted until 2020 Randomized controlled trials that have assessed the relationship between consumption of vitamin D fortified products and serum lipid profile were included. The relationship between fortification dose, dairy or non-dairy fortification as well as duration of intervention and plasma lipid profiles evaluated in separate sub-groups. Among serum lipids including total cholesterol(TC), triglyceride(TG), low density lipoprotein(LDL) and high density lipoprotein(HDL), fortification of vitamin D was reported to have a significant effect on reducing total cholesterol (pooled estimate: -0.089 mmol/L, 95%CI: -0.134 to -0.044, p<0.001). Its effect on other lipid profiles were not significant (LDL pooled estimate:-0.115 mmol/L, 95%CI:-0.238 to 0.008; HDL pooled estimate:0.024 mmol/L, 95%CI:-0.024 to 0.071; TG pooled estimate:-0.176mmol/L, 95%CI:-0.499 to 0.148). This meta-analysis demonstrated that vitamin D fortification could significantly reduce TC both in long and short term interventions and in different products. However this reduction, whilst statistically significant, may not be clinically important. The effect of fortification on other lipid profile components vary depending on dose and duration.