The above brief review indicates that the bioavailability of vitamin C in humans is complex and that our current understanding of that process and factors that influence it are incomplete. It is important that an overall pharmacokinetic scheme be developed and tested to completely describe the complex dispositional and absorption processes of the vitamin. Such information will provide a better ...

1 Jenne JW, Siever JR, Druz WS, Solano JV, Cohen SM, Sharp JT. The effect ofmaintenance theophylline therapy on lung work in severe chronic obstructive pulmonary disease while standing and walking. Am Rev Respir Dis 1984;130: 600-5. 2 Chrystyn H, Mulley BA, Peake MD. Dose response relation to oral theophylline in severe chronic obstructive airways disease. BMJ 1988;297: 1506-10. 3 Noseda A, Sch...

A prebiotic substance has been defined as a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon. Therefore, compared to probiotics, which introduce exogenous bacteria into the colonic microflora, a prebiotic aims at stimulating the growth of one or a limited number of the pote...

β-Carotene (BC), β-cryptoxanthin (CX) and α-carotene (AC) are common carotenoids that form retinol. The amount of retinol (vitamin A) formed from carotenoid-rich foods should depend chiefly on the bioavailability (absorption and circulation time in the body) of carotenoids from their major food sources and the selectivity and reactivity of carotene cleavage enzymes towards them. The objective o...

Oxygenated nonpolar organic contaminants (NOCs) are underrepresented in studies of the partitioning and bioavailability of NOCs, including nonylphenol. In this investigation, we evaluated the toxicity, partitioning, and bioavailability of nonylphenol as affected by different forms of organic carbon. Along with organic carbon content, the role of organic carbon polarity was assessed. Toxicity of...

Iron and vitamin A deficiencies in childhood are public health problems in the developing world. Introduction of cereal-based complementary foods, that are often poor sources of both vitamin A and bioavailable iron, increases the risk of deficiency in young children. Alternative foods with higher levels of vitamin A and bioavailable iron could help alleviate these micronutrient deficiencies. Th...

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is not an appropriate measure for its availability; bioavailability rather depends on the dynamic interplay of potential mass transfer (flux) of a compound to a microbial cell and the capacity of the latter to degrade the compound. In water-unsa...

Heme iron has been identified in many plant sources-most commonly in the root nodules of leguminous plants, such as soy. Our objective was to test the effectiveness of soy root nodule (SRN) and purified soy hemoglobin (LHb) in improving iron bioavailability using an in vitro Caco-2 cell model, with ferritin response as the bioavailability index. We assessed bioavailability of iron from LHb (eit...

Solubility is the process of dissolution of solid in liquid phase to give a homogenous system and is one of the important parameter to achieve desired concentration of drug in systemic circulation for pharmacological response. Dissolution rate of poorly water-soluble drugs is rate limiting step for its bioavailability so increase in bioavailability is the major challenging task in drug developm...

With the advent of present-day tools and techniques of analysis, it is possible and practical to measure accurately the essential trace element content of human foods. Although this is a major step forward in assessing nutrient needs and status, an important unknown remains. To meet nutritional requirements it is important to know not only the quantity consumed but the proportion of that consum...