Evaluation of the Potential for Olestra To Affect the Availability of Dietary Phytochemicals ,

Abstract

It has been hypothesized that phytochemicals found in fruits and vegetables are responsible for the inverse association observed between diets high in fruits and vegetables and risk of certain chronic diseases and cancer. This paper assesses the potential for olestra to affect the absorption of dietary phytochemicals and estimates the effect of olestra on the availability of carotenoids when olestra-containing snacks and foods containing carotenoids are eaten in free-living diets. Experimental data compiled on the effects of olestra on the availability of 29 compounds, mainly nutrients and oral medications, showed that olestra affects the availability of only molecules having octanol-water partition coefficients greater than approximately 7.5. Partition coefficients compiled for 382 dietary phytochemicals showed that only two classes of phytochemicals, phytosterols and carotenoids, contain molecules with octanol-water partition coefficients in the range in which olestra could potentially affect bioavailability. The potential effect on the bioavailability of phytosterols would be <10% and would not be expected to be of concern inasmuch as the hypothesized benefit of consuming pharmacological amounts of phytosterols is to reduce cholesterol availability, a function also of olestra. A 5.9% reduction in the average effective beta-carotene intake was calculated for individuals eating olestra-containing snack foods in free-living diets. The calculation was made by assuming that carotenoid bioavailability would be reduced to the extent measured in human clinical studies each time olestra-containing snacks and carotenoid-containing foods are eaten together and that all snacks eaten are made with olestra. Among individuals with low carotenoid intakes (the lowest 10%) the calculated reduction was 6.0%; for heavy snack eaters (the top 10%) it was 9.5%. These effects on carotenoid bioavailability are similar to those that can occur with other dietary factors.

Effect of the main dietary antioxidants (carotenoids, γ-tocopherol, polyphenols, and vitamin C) on α-tocopherol absorption

“…Concerning polyphenols, the second set of experiments showed that only naringenin impaired a-tocopherol absorption. The specific effect exhibited by naringenin needs to be elucidated by additional experiments, but it is striking that naringenin is the most lipophilic of all the polyphenols tested (log P ¼ 2.52 vs 0.86, 0.82 and 0.38 for gallic acid, caffeic acid and ( þ )-catechin, respectively (Cooper et al, 1997)). Thus, a first hypothesis is that naringenin affects a-tocopherol absorption through interaction with SR-BI, which is known to transport lipophilic molecules with low substrate specificity.…”

Glucosinolates inBrassicavegetables: The influence of the food supply chain on intake, bioavailability and human health

“…Because of its lipophilicity (log P (octanol/water) = 0.72 [186]) and a low molecular weight of 177, SFN rapidly diffused into the cells of the intestinal lining [185] were rapid conjugation with glutathione (GSH) is likely to be the driving force of this diffusion. As a result millimolar concentrations of intracellular SFN -GSH (several hundred fold over the extracellular concentration) have been determined in cell culture [187].…”

Respective effects of milk composition and the cheese-making process on cheese compositional variability in components of nutritional interest

“…Folates are water-soluble vitamins [18]. In milk, they are bound to hydrophilic folate-binding protein (FBP) in a 1:1 stoichiometry [83].…”