Autoimmune thyroiditis (Hashimoto disease) could be prevented and its course probably improved by selenium containing foods

What should you measure in the blood?

Vitamin D
Selenium 37.00 EUR unreimbursed

Glutathione peroxidase 26.00 EUR unreimbursed
Iron

TSH

T3 et T3 libre 

T4 et T4 libre

Where is selenium?

Mainly in animal foods
https://www.healthline.com/health/selenium-foods

https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/multiple-nutritional-factors-and-thyroid-disease-with-particular-reference-to-autoimmune-thyroid-disease/DBA9BAD5847376FA5E099B7ACC7556A2

https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/multiple-nutritional-factors-and-thyroid-disease-with-particular-reference-to-autoimmune-thyroid-disease/DBA9BAD5847376FA5E099B7ACC7556A2

You cannot rely on brazil nuts: "Selenium concentration in Brazil nuts can vary by about three orders of magnitude (0.2-512.0 mg/kg) across several regions of

South America (Chang et al., 1995; Secor and Lisk, 1989; Pacheco and Scussel, 2007; Parekh et al., 2008).
The issue with mushrooms is that it could work only if cultured mushrooms for instance Shiitake are enriched in Se: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1750-3841.2012.02837.x

A trial is on the way, just track the results

https://clinicaltrials.gov/ct2/show/NCT02013479

This RCT will probably improve the evidence about selenium supplementation which is uncertain:
https://www.ncbi.nlm.nih.gov/pubmed/23744563
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5272877/figure/Fig2/
https://www.ncbi.nlm.nih.gov/pubmed/27683225

And be careful about iodine!

Some studies in different countries have shown that increasing IODINE (virtually always in isolation without taking into consideration other nutrients) can lead to THYROIDITIS:


- Greece:
https://www.ncbi.nlm.nih.gov/pubmed/12855016
https://www.ncbi.nlm.nih.gov/pubmed/30267376


- China:
https://www.ncbi.nlm.nih.gov/pubmed/21444648
https://www.ncbi.nlm.nih.gov/pubmed/27370068
https://www.ncbi.nlm.nih.gov/pubmed/16807415


- Egypt:
https://www.ncbi.nlm.nih.gov/pubmed/18480555


- Brazil:
https://www.ncbi.nlm.nih.gov/pubmed/19554806
https://www.ncbi.nlm.nih.gov/pubmed/19219319