Assessment of the bioavailability and toxicokinetics of iodine when entering the body with compounds of serum proteins in a subchronic experiment

Introduction. Iodine deficiency disorders remain a relevant problem despite salt iodization programs. A promising direction is the  is the creation of organic forms of iodine with high biological availability, such as a complex with alpha-lactalbumin.

The aim of this study was to evaluate the bioavailability and toxicokinetics of this complex in a subchronic experiment.

Material and methods. During a 90-day experiment on mature male rats, the oral administration of the iodine-alpha-lactalbumin complex at a dose of 150 µg iodine/day was studied. The control group received a standard diet. Body weight, hematological and biochemical blood parameters, thyroid hormone levels (TSH, FT3, FT4), and total serum iodine content were assessed on days 45 and 90.

Results. The use of the complex led to a significant (2.2–3.2 times) increase in serum iodine levels, indicating its high bioavailability. By day 90, the experimental group animals developed iodine-induced hypothyroidism, manifested by a characteristic triad: an increase in TSH against a background of decreased FT4 and FT3. This was accompanied by metabolic disorders – decreased concentrations of glucose, total protein, and albumin. A paradoxical result was an increase in hemoglobin levels.

Limitations. The main limitation is the use of an animal model and a fixed iodine dosage, which does not allow full extrapolation of the obtained data to humans or assessment of dose-dependent effects.

Conclusion. Subchronic intake of iodine in the form of a complex with alpha-lactalbumin at a dose of 150 µg/day induces the development of iodine-induced hypothyroidism in rats against a background of high systemic bioavailability. The identified metabolic changes are consistent with a hypothyroid state, while the unexpected hematological effect requires further study. A promising direction is the investigation of the dose-dependent effects of the complex.

Compliance with ethical standards: The study was approved by the Bioethical Commission of the F.F. Erisman Federal Scientific Center of Hygiene (protocol from 09.04.24 No.1/24), and conducted in accordance with the European Convention for the Protection of Vertebrate Animals Used for Experiments or Other Scientific Purposes (ETS N 123), Directive 2010/63/EC of the European Parliament and of the Council of the European Union of 22.09.2010 on the protection of animals used for scientific purposes.

Authors’ contribution: All the authors have made an equal contribution to the writing of the article.

Conflict of interests. The authors declare no apparent and potential conflicts of interest in relation to the publication of this article.

Funding. The study was sponsored by I2LIFE Co., Ltd.

Received: Jule 14, 2025 / Revised: October 24, 2025 / Accepted: November 25, 2025 / Published: January 15, 2026

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