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Protein-corrected salivary iodide as a potential biomarker of individual iodine status: a proof-of-concept comparison with urinary iodine in groups with contrasting iodine intake

Published online by Cambridge University Press:  26 February 2026

Eatedal Eenizan Alsaeedi Open the ORCID record for Eatedal Eenizan Alsaeedi [Opens in a new window] ,
Peter Rose ,
Elizabeth H. Bailey  and
Simon J. M. Welham Open the ORCID record for Simon J. M. Welham [Opens in a new window]
Eatedal Eenizan Alsaeedi
Affiliation:
University of Nottingham, School of Biosciences, Division of Food, Nutrition and Dietetics, Loughborough, Leicestershire, UK University of Hafr Al Batin, College of Applied Medical Sciences, Division of Clinical Nutrition, Hafr Al Batin, Saudi Arabia
Peter Rose
Affiliation:
University of Nottingham, School of Biosciences, Division of Food, Nutrition and Dietetics, Loughborough, Leicestershire, UK
Elizabeth H. Bailey
Affiliation:
University of Nottingham, School of Biosciences, Division of Agriculture and Environmental Sciences, Loughborough, Leicestershire, UK
Simon J. M. Welham*
Affiliation:
University of Nottingham, School of Biosciences, Division of Food, Nutrition and Dietetics, Loughborough, Leicestershire, UK
*
Corresponding author: Simon J. M. Welham; Email: simon.welham@nottingham.ac.uk
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Abstract

Urinary iodine concentration (UIC) is the principal biomarker for assessing iodine status; however, it is subject to marked fluctuations and practical challenges. This proof-of-concept study evaluated protein-corrected salivary iodide (SI/P) as a potential alternative biomarker, comparing it with spot UIC in distinguishing between iodine-deficient and iodine-adequate individuals, assessing its responsiveness to short-term dietary iodine restriction and exploring its correlation with 24 h urinary iodine excretion (UIE). Twenty-six participants were categorised into low-iodine (n 17) and high-iodine (n 9) groups based on 24 h UIE collected on Day-1. Postprandial spot urine and unstimulated saliva samples were collected under habitual diet (Day-1) and low-iodine diet (Day-2). SI/P was significantly higher in the high-iodine group at all time points on both Day-1 (post-breakfast [1-PB]: 61·28 v. 27·89 µg/g, P = 0·03; post-lunch [1-PL]: 71·03 v. 27·4 µg/g, P = 0·003; post-dinner [1-PD]: 114·13 v. 31·58 µg/g, P = 0·002) and Day-2 (2-PB: 81·86 v. 26·51 µg/g, P = 0·013; 2-PL: 54·56 v. 18·83 µg/g, P < 0·001; 2-PD: 38·2 v. 18·79 µg/g, P = 0·043), whereas UIC only differed significantly post-dinner on Day-1 (156·15 v. 36·63 µg/l, P = 0·009). SI/P also showed stronger correlation with 24 h UIE (1-PB: r = 0·65, P = 0·001; 1-PL: r = 0·70, P < 0·001; 1-PD: r = 0·67, P < 0·001; 2-PB: r = 0·70, P < 0·001; 2-PL: r = 0·65, P = 0·001; 2-PD: r = 0·50, P = 0·01) compared with UIC (1-PB: r = 0·49, P = 0·011; 1-PL: r = 0·38, P = 0·055; 1-PD: r = 0·58, P = 0·002; 2-PB: r = 0·68, P < 0·001; 2-PL: r = 0·52, P = 0·007; 2-PD: r = 0·44, P = 0·027). Unlike UIC, which is primarily suited for population-level monitoring, SI/P demonstrated stable performance irrespective of diet/sampling time, suggesting utility as a reliable, individual-level biomarker of iodine status.

Keywords

IodineSalivary iodideSalivary proteinUrinary iodineInductively coupled plasma-mass spectrometry

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Type
Research Article
Information
British Journal of Nutrition , First View , pp. 1 - 13
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© The Author(s), 2026. Published by Cambridge University Press on behalf of The Nutrition Society

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