Phytosterol oxidation products in enriched foods: Occurrence, exposure, and biological effects

Abstract

Hypercholesterolemia is an important risk factor for the development of cardiovascular diseases. Dietary intake of phytosterols/phytostanols and their fatty acid esters results in a reduction of the LDL and total plasma cholesterol levels. Therefore, these constituents are added to a broad spectrum of foods. As in the case of cholesterol, thermo-oxidative treatment of phytosterols may result in the formation of phytosterol oxidation products (POPs), i.e. keto-, hydroxy-, and epoxy-derivatives. This review summarizes and evaluates the current knowledge regarding POPs in the light of the potentially increasing dietary exposure to these constituents via the consumption of foods enriched with phytosterols/phytostanols and their esters. Data on the occurrence of POPs and approaches to assess the potential intake of POPs resulting from the consumption of enriched foods are described. The knowledge on the uptake of POPs and the presently available data on the impact of the consumption of enriched foods on the levels of POPs in humans are discussed. Biological effects of POPs, such as potential proatherogenic properties or the loss of the cholesterol-lowering effects compared to nonoxidized phytosterols, are discussed. Finally, knowledge gaps are outlined and recommendations for further research needed for a safety assessment of POPs are presented.

Scientific Opinion on the safety of UV‐treated bread as a novel food EFSA Panel on Dietetic Products, Nutrition and Allergies

“…The contents of total phytosterols reported in bread range from 40.5 mg/100 g dry weight (white bread) to 80.3 mg/100 g dry weight (rye bread made from rye and wheat flour) and 90.2 mg/100 g dry weight (rye bread made only from rye flour) (Piironen et al, 2002). Assuming that the maximum oxidation rate for phytosterols upon UV treatment is in the same order of magnitude as the maximum oxidation rate (1 %) reported for phytosterols following thermal processing (Scholz et al, 2015), phytosterol oxidation products expected in bread as a result of the UV treatment would amount to, approximately, 0.4-0.9 mg/100 g dry weight. Taking into account the short time of the UV treatment and the fact that UV-induced oxidations would occur in only the outer layer of the bread, the formation of phytosterol oxidation products is not considered to be of relevance.…”

Photooxidation of phytochemicals in food and control: a review

“…These photooxidation products were similar to the oxidation products produced by phytosterol autoxidation. Phytosterol oxidation products (POPs) were considered a potential risk to human health, but no experimental results clearly support this view . Ergosterol is the major sterol distributed in higher fungi, with two double bonds within the sterol ring structure instead of one.…”

Cytotoxic activity of stigmasteryl esters and products of their thermo-oxidative degradation against drug sensitive and drug resistant human acute lymphoblastic leukemia cells

“…Oxidation of phytosterols and their fatty acid esters through multiple reactions leads to primary (hydroperoxides), secondary (polar: ketones, epoxides, alcohols; nonpolar: dienes, trienes) and tertiary (dimers, oligomers, polymers) oxidation products. Most research has focused on primary and secondary polar compounds (García-Llatas and Rodríguez-Estrada, 2011;Scholz et al, 2015). However, the most abundant from oxides, formed during sterol degradation at elevated temperatures, are dimers, which are bound mostly by ether (C-O-C) or peroxy (C-O-O-C) linkages (Sosińska et al, 2014).…”