Microalgae-derived sterols do not reduce the bioavailability of oral vitamin D₃ in mice

Abstract

Abstract. Microalgae have drawn increasing attention as sustainable food sources, also because of their lipid-lowering phytosterols. As phytosterols are also discussed critically regarding their effect on the availability of fat-soluble vitamins, this study aimed to investigate microalgae-derived phytosterols and their effect on vitamin D status. GC–MS analysis showed large variations in the phytosterol profiles of microalgal species. The most frequent sterols were β-sitosterol and stigmasterol. To investigate their effects on vitamin D status, 40 mice were randomized to four groups and fed a vitamin D3-adequate (25 μg/kg) Western-style diet with 0% phytosterols (control) or 1% ergosterol (a fungal sterol not typical for microalgae), β-sitosterol or stigmasterol for four weeks. Contrary to the hypothesis that phytosterols adversely affect vitamin D uptake, mice fed β-sitosterol had significantly higher concentrations of vitamin D3 in plasma (3.15-fold, p<0.01), liver (3.15-fold, p<0.05), and skin (4.12-fold, p<0.005) than the control group. Small increases in vitamin D3 in plasma and skin were also observed in mice fed stigmasterol. In contrast, vitamin D3 levels in the ergosterol and control groups did not differ. The increased tissue levels of vitamin D3 in mice fed β-sitosterol and stigmasterol were not attributable to the observed reduction in liver triglycerides in these groups. The data rather suggest that changes in bile acid profiles were responsible for the beneficial effect of microalgae sterols on the bioavailability of vitamin D3. In conclusion, consumption of microalgae might not adversely affect vitamin D status.

The Clinical Promise of Microalgae in Rheumatoid Arthritis: From Natural Compounds to Recombinant Therapeutics

“…For example, some microalgal strains are sustainable sources of the lipid-based prohormone vitamin D 3 , the biosynthetic precursor of the biologically active 1,25-dihydroxyvitamin D (calcitriol) [318,319] whose deficiency is a major risk factor for RA [320,321]. Several microalgae accumulate bioactive ergosterol and β-sitosterol [322,323], precursors of vitamin D 2 (ergocalciferol) and D 3 , respectively [324,325]. Moreover, the chlorophyte Botryococcus braunii (Trebouxiophyceae) and Schizochytrium mangrovei can be engineered to hyperaccumulate squalene, an anti-inflammatory triterpene and precursor of ergosterol [326][327][328][329][330][331].…”