Scientists posit vitamin D benefits in alleviating “incurable” Hashimoto’s disease

18 Jul 2023 --- Hashimoto’s thyroiditis (HT), a common autoimmune thyroid condition has been spotlighted by two researchers from the Medical University of Gdańsk in Poland who analyzed the immunomodulatory activity of vitamin D in the autoimmune process of the condition.

Their article published in the nutrients section of MDPI discusses the potential impact of vitamin D on various immune pathways in HT, with current evidence supporting the potential role of vitamin D in preventing and managing the disease.

Vitamin D supplementation has shown promise in reducing antithyroid antibody levels, improving thyroid function and other markers of autoimmunity such as cytokines. HT has an unpredictable nature that can lead to lymphocytic destruction of the thyroid gland, which requires a lifetime of thyroid hormone replacement.

Immune pathways to explore
Recent studies show that interventions within modifiable risk factors might improve immunological and clinical outcomes for HT. These include selenium and vitamin D supplements, dietary changes and stress management.

HT has a complex etiopathology that includes genetic and environmental factors, such as past infections, medications, smoking and the level of microelements, including iodine, iron and selenium. 

According to the researchers, vitamin D may help control autoimmunity and improve thyroid function by impacting immunological mechanisms in the body. It is a fat-soluble vitamin that plays a crucial role in bone health and calcium regulation in the body. 

When vitamin D is consumed or synthesized, it undergoes hydroxylation in the liver, where it is converted into 25-hydroxyvitamin D. Then it is transported to the kidneys, where it undergoes a second hydroxylation step to become the biologically active form of vitamin D known as calcitriol.Vitamin D’s positive influence on the immune system at the cellular and molecular level translates to improved clinical outcomes in many autoimmune diseases. 

Calcitriol binds to vitamin D receptors in various tissues throughout the body, including the bones, intestines and kidneys, to regulate calcium and phosphate metabolism. In the intestines, calcitriol increases the absorption of calcium and phosphorus, while in the kidneys, it increases calcium reabsorption and phosphate excretion. It also helps regulate bone remodeling and mineralization, ensuring proper bone growth and maintenance.

Research shows that the pleiotropic effects of calcitriol are significant for disease prevention. Many studies have linked vitamin D to health benefits such as mood regulation, reduced risk of chronic cardiovascular diseases and immune function.

Academic controversy around HT hypothesis
The association between vitamin D and HT remains controversial and experts underscore that the results of many studies investigating the issue within various populations need to be more consistent.

There have been those studies that show that vitamin D may induce the expression of antibiotic peptides that destroy bacteria and viruses’ cell membranes. It enhances autophagy in macrophages, which helps clear viruses from the cells. 

A recent review of three clinical trials published in the Annals of Internal Medicine showed that adults with prediabetes who take vitamin D supplements are 15% less likely to develop diabetes.

However, a few studies have yielded contrasting findings. For example, research has explored the association between vitamin D and other immunological parameters in HT, such as cytokines and T-cell subsets. While the results have been mixed, some studies show a significant negative correlation between 25-hydroxyvitamin D concentration and inflammatory cytokines.

On the opposite end of the spectrum, several clinical trials and observational studies demonstrated that vitamin D supplementation may benefit the prevalence and disease activity of multiple autoimmune conditions, including rheumatoid arthritis, inflammatory bowel disease and vitiligo. 

Further studies are needed to fully understand its mechanisms of action and potential therapeutic benefits for HT.

Meanwhile, calcifediol – the active form of vitamin D – can play a significant role in absorption, paving the way for innovation, according to DSM. With consumers increasingly turning to vitamin D for its link to immunity, the vitamin continues to be in demand for supplementation.

By Inga de Jong