Iodine Excretion and Accumulation in Seaweed-Eating Sheep from Orkney, Scotland

Y. Lu, S. Suliman, H. R. Hansen, Jorg Feldmann

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Iodine concentrations in tissue and urine samples of 11 seaweed-eating sheep from North Ronaldsay in Orkney, Scotland, were measured during a feeding experiment. Two groups of six sheep ( control was kept on grass five months before experiment, while the trial group were caught at the beach) each ate 0.5 +/- 0.1 kg dry mass of seaweed ( Laminaria digitata and Laminaria hyperborea) each day in an 11-day feeding trial and had a body burden of around 2300 mg iodine daily, almost entirely as iodide. This iodine intake of 124 mg I kg bodyweight(-1) is more than 60 000 times higher than the recommended daily intake for humans. The iodine concentration in the urine within 4 h after the seaweed meal was 1295 +/- 369 mg I kg(-1). Thus, more than 66% of the total iodine ingested by the sheep was excreted within 24 h. The iodine excretion of the control group was slightly slower (T-1/2 = 15.9 +/- 7.2 h) than that of the trial group (T-1/2 = 9.1 +/- 1.6 h). In the same experiment, the excretion of iodine was faster than that of arsenic (T-1/2 = 24.3 h). Tissue samples from feral North Ronaldsay sheep taken directly from the beach showed elevated iodine levels (liver: 2710 +/- 505 mu g I kg(-1) > kidney: 1827 +/- 618 mu g I kg(-1) > neck muscles: 404 +/- 117 mu g I kg(-1) based on fresh weight), pointing to insufficient homeostatic control of iodine uptake, so that iodine concentrations were 17 times higher than those of non-exposed sheep. A trend of continuous accumulation of iodine in the liver and kidney throughout the life of the sheep was observed. In contrast to arsenic, iodine was higher in the liver and kidney than in the muscle.

Original languageEnglish
Pages (from-to)338-344
Number of pages6
JournalEnvironmental Chemistry
Volume3
DOIs
Publication statusPublished - 2006

Keywords

  • agricultural chemistry
  • bioavailability
  • homeostatic regulation
  • nutrition
  • I-125 LABELED RATS
  • NORTH RONALDSAY
  • METABOLISM
  • DEFICIENCY
  • TOXICITY
  • DIET

Cite this

Iodine Excretion and Accumulation in Seaweed-Eating Sheep from Orkney, Scotland. / Lu, Y.; Suliman, S.; Hansen, H. R.; Feldmann, Jorg.

In: Environmental Chemistry, Vol. 3, 2006, p. 338-344.

Research output: Contribution to journalArticle

@article{fd42f6dd66754b67bdb77ebe3b7e0f06,
title = "Iodine Excretion and Accumulation in Seaweed-Eating Sheep from Orkney, Scotland",
abstract = "Iodine concentrations in tissue and urine samples of 11 seaweed-eating sheep from North Ronaldsay in Orkney, Scotland, were measured during a feeding experiment. Two groups of six sheep ( control was kept on grass five months before experiment, while the trial group were caught at the beach) each ate 0.5 +/- 0.1 kg dry mass of seaweed ( Laminaria digitata and Laminaria hyperborea) each day in an 11-day feeding trial and had a body burden of around 2300 mg iodine daily, almost entirely as iodide. This iodine intake of 124 mg I kg bodyweight(-1) is more than 60 000 times higher than the recommended daily intake for humans. The iodine concentration in the urine within 4 h after the seaweed meal was 1295 +/- 369 mg I kg(-1). Thus, more than 66{\%} of the total iodine ingested by the sheep was excreted within 24 h. The iodine excretion of the control group was slightly slower (T-1/2 = 15.9 +/- 7.2 h) than that of the trial group (T-1/2 = 9.1 +/- 1.6 h). In the same experiment, the excretion of iodine was faster than that of arsenic (T-1/2 = 24.3 h). Tissue samples from feral North Ronaldsay sheep taken directly from the beach showed elevated iodine levels (liver: 2710 +/- 505 mu g I kg(-1) > kidney: 1827 +/- 618 mu g I kg(-1) > neck muscles: 404 +/- 117 mu g I kg(-1) based on fresh weight), pointing to insufficient homeostatic control of iodine uptake, so that iodine concentrations were 17 times higher than those of non-exposed sheep. A trend of continuous accumulation of iodine in the liver and kidney throughout the life of the sheep was observed. In contrast to arsenic, iodine was higher in the liver and kidney than in the muscle.",
keywords = "agricultural chemistry, bioavailability, homeostatic regulation, nutrition, I-125 LABELED RATS, NORTH RONALDSAY, METABOLISM, DEFICIENCY, TOXICITY, DIET",
author = "Y. Lu and S. Suliman and Hansen, {H. R.} and Jorg Feldmann",
year = "2006",
doi = "10.1071/EN06041",
language = "English",
volume = "3",
pages = "338--344",
journal = "Environmental Chemistry",
issn = "1448-2517",
publisher = "CSIRO",

}

TY - JOUR

T1 - Iodine Excretion and Accumulation in Seaweed-Eating Sheep from Orkney, Scotland

AU - Lu, Y.

AU - Suliman, S.

AU - Hansen, H. R.

AU - Feldmann, Jorg

PY - 2006

Y1 - 2006

N2 - Iodine concentrations in tissue and urine samples of 11 seaweed-eating sheep from North Ronaldsay in Orkney, Scotland, were measured during a feeding experiment. Two groups of six sheep ( control was kept on grass five months before experiment, while the trial group were caught at the beach) each ate 0.5 +/- 0.1 kg dry mass of seaweed ( Laminaria digitata and Laminaria hyperborea) each day in an 11-day feeding trial and had a body burden of around 2300 mg iodine daily, almost entirely as iodide. This iodine intake of 124 mg I kg bodyweight(-1) is more than 60 000 times higher than the recommended daily intake for humans. The iodine concentration in the urine within 4 h after the seaweed meal was 1295 +/- 369 mg I kg(-1). Thus, more than 66% of the total iodine ingested by the sheep was excreted within 24 h. The iodine excretion of the control group was slightly slower (T-1/2 = 15.9 +/- 7.2 h) than that of the trial group (T-1/2 = 9.1 +/- 1.6 h). In the same experiment, the excretion of iodine was faster than that of arsenic (T-1/2 = 24.3 h). Tissue samples from feral North Ronaldsay sheep taken directly from the beach showed elevated iodine levels (liver: 2710 +/- 505 mu g I kg(-1) > kidney: 1827 +/- 618 mu g I kg(-1) > neck muscles: 404 +/- 117 mu g I kg(-1) based on fresh weight), pointing to insufficient homeostatic control of iodine uptake, so that iodine concentrations were 17 times higher than those of non-exposed sheep. A trend of continuous accumulation of iodine in the liver and kidney throughout the life of the sheep was observed. In contrast to arsenic, iodine was higher in the liver and kidney than in the muscle.

AB - Iodine concentrations in tissue and urine samples of 11 seaweed-eating sheep from North Ronaldsay in Orkney, Scotland, were measured during a feeding experiment. Two groups of six sheep ( control was kept on grass five months before experiment, while the trial group were caught at the beach) each ate 0.5 +/- 0.1 kg dry mass of seaweed ( Laminaria digitata and Laminaria hyperborea) each day in an 11-day feeding trial and had a body burden of around 2300 mg iodine daily, almost entirely as iodide. This iodine intake of 124 mg I kg bodyweight(-1) is more than 60 000 times higher than the recommended daily intake for humans. The iodine concentration in the urine within 4 h after the seaweed meal was 1295 +/- 369 mg I kg(-1). Thus, more than 66% of the total iodine ingested by the sheep was excreted within 24 h. The iodine excretion of the control group was slightly slower (T-1/2 = 15.9 +/- 7.2 h) than that of the trial group (T-1/2 = 9.1 +/- 1.6 h). In the same experiment, the excretion of iodine was faster than that of arsenic (T-1/2 = 24.3 h). Tissue samples from feral North Ronaldsay sheep taken directly from the beach showed elevated iodine levels (liver: 2710 +/- 505 mu g I kg(-1) > kidney: 1827 +/- 618 mu g I kg(-1) > neck muscles: 404 +/- 117 mu g I kg(-1) based on fresh weight), pointing to insufficient homeostatic control of iodine uptake, so that iodine concentrations were 17 times higher than those of non-exposed sheep. A trend of continuous accumulation of iodine in the liver and kidney throughout the life of the sheep was observed. In contrast to arsenic, iodine was higher in the liver and kidney than in the muscle.

KW - agricultural chemistry

KW - bioavailability

KW - homeostatic regulation

KW - nutrition

KW - I-125 LABELED RATS

KW - NORTH RONALDSAY

KW - METABOLISM

KW - DEFICIENCY

KW - TOXICITY

KW - DIET

U2 - 10.1071/EN06041

DO - 10.1071/EN06041

M3 - Article

VL - 3

SP - 338

EP - 344

JO - Environmental Chemistry

JF - Environmental Chemistry

SN - 1448-2517

ER -