Investigation of iodine bioavailability from chicken eggs versus iodized kitchen salt with in vitro method

Abstract

The goal of the presented studies was to investigate speciation and bioavailability of iodine from chicken eggs versus iodized kitchen salt with an in vitro method. Determination of iodine total content in chicken eggs and iodized kitchen salt was carried out by inductively coupled plasma mass spectrometry (ICP MS). The majority of iodine was accumulated in the yolk-the concentration was even 37 times higher than in white. Chicken eggs were treated with buffer (Tris HCl pH = 7.5) and enzymatic extraction media and analyzed by size exclusion chromatography hyphenated with inductively coupled plasma mass spectrometry (SEC ICP MS). The enzymatic extraction being an in vitro bioavailability assessment method was based on two-stage digestion model simulating gastric (pepsin digestion) and intestinal (pancreatin digestion) juices. Speciation analyses along with bioavailability studies presented iodide as the major form in chicken eggs. The bioavailability was established as 33% from white and 10% from yolk and decreased with longer time of boiling. It allows to suggest that the majority of iodine remains in forms bound to non-digestible coagulated and waterinsoluble proteins.

The effects of iodine level and source on iodine carry-over in eggs and body tissues of laying hens

“…Together with other iodine containing food Wagner et al 2009), the UL of 500 mg I/d (D-A-CH 2008) or 1000 mg I/d (WHO 1994) can be reached easily. Nevertheless, from an in vitro study was concluded that the bioavailability of iodine from eggs amounted to about 30% only (Lipiec et al 2012). But to verify this result and to derive final conclusions, more in vivo studies on this issue are necessary.…”

Analysis of iodine and its species in animal tissues

“…thyroid hormones, high molecular weight proteins). [3][4][5] In food with a plant origin, such as forage, hay or vegetables, iodine is primarily present in form of iodide. [6] The bioavailability of iodide for mammals is 96%, while the bioavailability of organic species, such as monoiodotyrosine (MIT), is only 80%.…”

“…[14] Moreover, iodide can be found in body fluids, such as blood, urine, sweat or breast milk, and in the case of birds also in eggs. [4,15] KEYWORDS Iodine; speciation; animal tissue; ICP-MS; size-exclusion chromatography OPEN ACCESS sample preparation were used almost exclusively for the determination of the total iodine content. [3,8,34,35] Only two papers concerning iodine speciation in animal tissue samples were recently published.…”

Atomic spectrometry update. Clinical and biological materials, foods and beverages

“…Nobias Chelate PB-1 and, more effectively, InertSep ME-1 were used to remove nearly 100% Mo, Sn and Zr from samples at pH 7. Comparison of I speciation and bioavailability between iodized salt and chicken eggs was carried out by Lipiec et al 134 A two-stage simulated digestion (pepsin followed by pancreatin) of both egg yolk and albumin was devised and I determined by SEC-ICP-MS. Yolk contained 37-times more I than the white while the bioavailability from the former was 10% and from the white it was 33%; this is in contrast to 100% availability of I À in kitchen salt. However, the bioavailability from egg yolk decreased with cooking indicating I remains bound to non-digestible, coagulated and insoluble proteins.…”