Emerging evidence indicates that carotenoids may have particular roles in infant nutrition and development, yet data on the profile and bioavailability of carotenoids from human milk remain sparse. Milk was longitudinally collected at 2, 4, 13, and 26 weeks postpartum from twenty mothers each in China, Mexico, and the USA in the Global Exploration of Human Milk Study (n = 60 donors, n = 240 samples). Maternal and neonatal plasma was analyzed for carotenoids from the USA cohort at 4 weeks postpartum. Carotenoids were analyzed by HPLC and total lipids by Creamatocrit. Across all countries and lactation stages, the top four carotenoids were lutein (median 114.4 nmol/L), β-carotene (49.4 nmol/L), β-cryptoxanthin (33.8 nmol/L), and lycopene (33.7 nmol/L). Non-provitamin A carotenoids (nmol/L) and total lipids (g/L) decreased (p<0.05) with increasing lactation stage, except the provitamin A carotenoids α- and β-cryptoxanthin and β-carotene did not significantly change (p>0.05) with lactation stage. Total carotenoid content and lutein content were greatest from China, yet lycopene was lowest from China (p<0.0001). Lutein, β-cryptoxanthin, and β-carotene, and lycopene concentrations in milk were significantly correlated to maternal plasma and neonatal plasma concentrations (p<0.05), with the exception that lycopene was not significantly associated between human milk and neonatal plasma (p>0.3). This enhanced understanding of neonatal exposure to carotenoids during development may help guide dietary recommendations and design of human milk mimetics.

Biofortified sorghum (Sorghum bicolor (L.) Moench) lines are being developed to target vitamin A deficiency in Sub-Saharan Africa, but the delivery of provitamin A carotenoids from such diverse germplasms has not been evaluated. The purpose of this study was to screen vectors and independent transgenic events for the bioaccessibility of provitamin A carotenoids using an in vitro digestion model. The germplasm background and transgenic sorghum contained 1.0-1.5 and 3.3-14.0 μg/g β-carotene equivalents on a dry weight basis (DW), respectively. Test porridges made from milled transgenic sorghum contained up to 250 μg of β-carotene equivalents per 100 g of porridge on a fresh weight basis (FW). Micellarization efficiency of all-trans-β-carotene was lower (p < 0.05) from transgenic sorghum (1-5%) than from null/nontransgenic sorghum (6-11%) but not different between vector constructs. Carotenoid bioaccessibility was significantly improved (p < 0.05) by increasing the amount of coformulated lipid in test porridges from 5% w/w to 10% w/w. Transgenic sorghum event Homo188-A contained the greatest bioaccessible β-carotene content, with a 4-8-fold increase from null/nontransgenic sorghum. While the bioavailability and bioconversion of provitamin A carotenoids from these grains must be confirmed in vivo, these data support the notion that biofortification of sorghum can enhance total and bioaccessible provitamin A carotenoid levels.

Inadequate data on tissue distribution of vitamin D and its metabolites remains a barrier to defining health outcomes of vitamin D intake and 25-hydroxyvitamin D (25(OH)D) status. The purpose of this study was to develop a method for the analysis of vitamin D2 (ergocalciferol), vitamin D3 (cholecalciferol), 25(OH)D2, and 25(OH)D3 in soft tissues, and determine distribution in select tissues from a dose-response study of vitamin D2 and vitamin D3 in rats. Liver, gastrocnemius muscle, and epididymal fat homogenates were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization following liquid-liquid extraction, solid-phase extraction, and derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD). A dose-response was observed in most tissues for vitamin D and 25(OH)D from both vitamers. Vitamin D concentration was greater in epididymal fat than gastrocnemius muscle and liver, but 25(OH)D concentration was not significantly different between tissues. Soft tissues of rats fed crystalline vitamin D3 had higher concentrations of total vitamin D than those of rats fed yeast-derived vitamin D2, while total 25(OH)D concentrations were similar between vitamin D sources. This method is well suited to more complete studies of vitamin D bioavailability and metabolite tissue distribution.

The assessment of the efficacy of dietary and supplemental vitamin D tends to be confounded by differences in the serum 25-hydroxyvitamin D response between vitamin D and vitamin D. Serum response differences from these vitamers may be due to differences in bioavailability. To address this specifically, the bioaccessibility was assessed for vitamin D from breads fortified with UV-treated yeast, and a benchmark against staple vitamin D fortified foods including bovine milks and infant formula, as well as crystalline vitamin D fortified bread. Fortified foods were subjected to a three-stage static in vitro digestion model, and vitamin D was analyzed by HPLC-MS. Vitamin D bioaccessibility was significantly greater from bovine milks and infant formula (71-85%) than from yeast-fortified sandwich breads (6-7%). Bioaccessibility was not different between whole wheat and white wheat bread (p > 0.05), but was ∼4× lower from yeast-fortified bread than from crystalline vitamin D fortified bread (p < 0.05). Intact yeast cells were observed in the digesta of yeast fortified bread. These results indicate that the low bioavailability of yeast D in comparison to other vitamin D sources is likely due to entrapment within a less digestible yeast matrix and not only to metabolic differences between vitamins D and D.

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