Bioaccessibility and tissue distribution of carotenoids and vitamin D from fortified foods

Novel approaches to food fortification are being developed in order to meet dietary gaps in micronutrient intake. The efficacy of food fortification relies on bioavailability of the nutrient, i.e. the nutrient must be released from the food matrix during digestion, absorbed at the intestinal epithelial surface, and delivered to target tissues for biological activity and/or storage. Underlying the investigation of bioavailability is the need for analytical methods to determine carotenoid and vitamin D concentrations in foods and tissues. The bioaccessibility and tissue distribution of carotenoids and vitamin D were investigated from three distinct food systems. Provitamin A carotenoid levels of sorghum are being enhanced through transgenic approaches in the Africa Biofortified Sorghum project, yet bioavailability of carotenoids has not been considered. Bioaccessibility of provitamin A carotenoids were assessed from 18 biofortified and wild-type sorghum varieties by in vitro digestion. The most promising biofortified variety was identified, and contained 4-8x more bioaccessible β-carotene equivalents than wild-type sorghum. Human breast milk is a primary source of bioactive carotenoids including lutein and zeaxanthin, which may protect the developing infant retina from light-induced damage. To develop additional insights into carotenoid profiles across lactation stage and country, human milk was analyzed from twenty donors in China, Mexico, and the USA at 2, 4, 13, and 26 weeks postpartum. Bioaccessibility and intestinal absorption of breast milk from 1-6 months postpartum and 9 prototypes of lutein-fortified infant formula were assessed by a coupled in vitro digestion/ Caco-2 human intestinal cell model. Bioaccessibility of lutein was not different between human milk (29±2%) and infant formula (36±4%), or between types of lutein-fortified formula. However, accumulation efficiency of lutein by Caco-2 from human milk was over 4x greater from human milk than infant formula and increasingly efficient at low levels of lutein. Sample preparation and LC-MS/MS methodology was developed in order to assess the tissue distribution of vitamin D and 25-hydroxyvitamin D from select soft tissues. 25-hydroxyvitamin D concentrations were ~1 ng/g from both vitamin D forms in muscle, liver, and adipose tissue. Total vitamin D concentration in adipose tissue reflected serum 25-hydroxyvitamin concentration, suggesting that potential differences in tissue accumulation did not cause the disparity in bioavailability. To isolate digestive processes from further metabolism, vitamin D bioaccessibility from fortified breads and bovine milks was assessed by in vitro digestion. Vitamin D bioaccessibility was lower from bread fortified with vitamin D2 enriched yeast than from crystalline vitamin D2 fortified breads and from bovine milks. Microscopy and solvent extraction of breads further suggests that vitamin D was not released from intact yeast cells. Together, these studies strongly indicate that increasing the carotenoid or vitamin D content of foods is not sufficient for effective fortification. Carotenoid and vitamin D bioaccessibility and absorption are a function of the food matrix these nutrients are placed into. Bioavailability is not only influenced by macronutrients such as lipid to aid in micellarization, but also the microenvironment that may physically trap or chemically associate with the nutrient, as well as biological factors that may potentiate intestinal absorption. While similar observations have been made before for other food systems, these data highlight the necessity of bioavailability assessment from any novel approach to fat-soluble micronutrient fortification. (Abstract shortened by UMI.

Stellar wind interaction with planetary nebulae

It has been proposed by other authors that a stellar wind might provide a pressure support at the inner edge of a planetary nebula to prevent the inward motion of material and to insure the ring-like appearance common to most planetary nebulae. The interaction of a supersonic stellar wind with a planetary nebula is examined with three models. In the shock-relation model the shock relations are generalized to allow for arbitrary changes in the mass, momentum and energy flux of the stellar wind. It is found that there exists a restrictive lower limit on the amount of energy that can be removed from a supersonic flow and still satisfy the shock relations. It is concluded that a supersonic stellar wind can not flow into a planetary and cool to observed planetary temperatures (~ 10 °K) and that a shock front must exist between the central star and planetary to reduce the flow to subsonic velocities before reaching the planetary. In the radiation model the subsonic stellar wind is allowed to lose energy by radiation only. It is concluded that the stellar wind does not significantly cool in a distance the order of a planetary radius (~ 104 A.U.), and that in order for the flow to be cooled and slowed to observed planetary expansion velocities (10-30 km/sec), the flow must first transfer energy and momentum to the planetary. In the third model the flow is allowed to transfer energy in coulomb collisions and momentum through a viscous force term to a stationary planetary that is heated by ionization-recombination processes and cooled by radiating in the N1 and N2 forbidden lines of OIII. The distances involved in the solutions are less than the mean free path of the flow particles. It is concluded that processes other than those dominant in the main body of the planetary may need to be taken into account in the region of interaction and that the assumption that fluid dynamics may be applied to this flow problem may not be valid

Bioaccessibility of carotenoids from transgenic provitamin A biofortified sorghum

PRIFPRI3; ISI; CRP4; HarvestPlusHarvestPlus; A4NHCGIAR Research Program on Agriculture for Nutrition and Health (A4NH

Longitudinal Survey of Carotenoids in Human Milk from Urban Cohorts in China, Mexico, and the USA.

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