Many epidemiological studies have emphasised the relation between carotenoid dietary intake and their circulating concentrations and beneficial health effect, such as lower risk of cardiometabolic diseases and cancer. However, there is dispute as to whether the attributed health benefits are due to native carotenoids or they are rather induced by their metabolites. Several categories of metabolites have been reported, most notably due to a) modifications at the cyclohexenyl-ring or the polyene chain, such as epoxides and geometric isomers, b) excentric cleavage metabolites with also alcohol-, aldehyde- or carboxylic acid-functional groups or c) centric cleaved metabolites with additional hydroxyl-, aldehyde- or carboxyl-functionalities, not counting their potential phase-II glucuronidated/sulphated derivatives. Of special interest are the apo-carotenoids, which originate in the intestine and other tissues from carotenoids cleavage by beta-carotene oxygenases 1/2 in a symmetrical/non-symmetrical fashion. These are more water soluble and more electrophilic, and therefore putative candidates for interactions with transcription factors such as NF-kB and Nrf2, as well as ligands for RAR-RXR nuclear receptor interactions. In this review, we discuss in vivo detected apo-carotenoids, their reported tissue concentrations, and potential associated health effects, focussing exclusively on the human situation and based on quantified/semi-quantified carotenoid-metabolites proven to be present in humans.

BackgroundVitamin D (VitD) is involved in lung development but its influence on respiratory distress syndrome of extremely preterm (EPT) infants have been little investigated. In this study, we examined the influence of low vitamin D status at birth on early respiratory outcomes of this vulnerable infant population.MethodsCord blood 25(OH)D levels ≤ 75 nmol/L were considered as Low vitamin D levels. Stepwise logistic regression and classification regression-tree analyses were used and the primary outcome was the combined outcome of death or mechanical ventilation need by the end of the first week (death or MV DoL7) as a marker od RDS severity.ResultsThe mean (SD) GA and birth weight were 26 (1.4) weeks and 801 (212) gr, respectively; 81/109 (74%) infants had low 25(OH)D levels. Infants with low VitD levels had 25% higher initial FiO2 levels (p < 0.05) and were more likely to be mechanically ventilated on DoL7 (36 vs. 7%, p < 0.05). Adjusted for gestational age, they had 10-fold higher odds of death or MV DoL7 (p < 0.01). By regression tree analysis, the rate of death or MV DoL7 increased from 18 to 71% in infants with GA < 26 weeks and with cord blood 25(OH)D levels higher and lower than 74 nmol/L, respectively (p < 0.05).ConclusionLow vitamin D levels at birth are associated with early adverse respiratory outcomes in infants with GA less 29 weeks. Further largest studies are needed to confirm this association.