Hormone Health Hub: Expert Insights on Testing, Balance & Better Living — glutathione peroxidase

Brazil nuts are widely used as a natural selenium supplement, but the selenium content in each nut varies enormously depending on soil conditions, region, and even individual trees. While selenium is essential for thyroid function, antioxidant defence, and overall health, both deficiency and excess carry serious risks. This article explains why Brazil nuts are so variable as a selenium source, what the safe daily intake looks like, and why testing your selenium levels is the most reliable way to know whether your intake is adequate, insufficient, or dangerously high.

Iodine is an essential trace element required for thyroid hormone production, yet many people are unknowingly deficient. While iodised salt and seafood are well-known sources, dairy products, eggs, and seaweed also contribute significantly to daily intake. Changing dietary habits — including reduced milk consumption and the replacement of iodine with bromine in bread production — are quietly lowering iodine intake across the population. This article explains where dietary iodine comes from, why the body needs it, how it is absorbed and excreted, and how at-home urine testing can confirm whether your intake is adequate.

Normal thyroid blood tests don’t always explain why patients still suffer from fatigue, cold intolerance, brain fog and weight gain. In this in-depth clinical article, ZRT Laboratory explains the critical role of selenium in thyroid hormone synthesis and T4-to-T3 conversion, how heavy metals like mercury and arsenic sequester selenium and inactivate protective antioxidant enzymes, and why this can trigger Hashimoto’s thyroiditis — even when TSH, T4 and T3 appear normal.