Is There a Connection Between Vitamin D and Hashimoto's Disease? Does Vitamin D Supplementation Help Heal Hashimoto's Disease?
Vitamin D has long been established in literature as a highly essential nutrient with benefit to the musculoskeletal system and bone density. It also functions in the body as an immunomodulator, facilitating normal immune system function and improving resistance against certain diseases.
Given this background, one has to wonder if a deficiency in vitamin D would be prevalent among individuals with Hashimoto’s thyroiditis and if so, would supplementation with vitamin D help patients manage the disease or perhaps even prevent it?
PART ONE – Vitamin D Deficiency and Hashimoto’s Disease
Research goes back to 2009 on the first question: is there a connection between vitamin D deficiency and Hashimoto’s disease? The earlier studies either indicated that indeed there was a connection while other studies concluded that there was none at all. How is one to draw a final answer when the outcomes are 180 degrees apart?
Kmiec and Sworczak (2015) reviewed twelve studies published between 2009 and 2014 whereby seven of those studies concluded that there was a connection between lower vitamin D levels and Hashimoto’s thyroiditis while two other studies showed no association and three others were inconclusive.
Among the studies that established a connection included the ones by Bozkurt et al. (2013), Camurdan et al. (2012) and Mansournia et al. (2014).
Goswami et al. (2009) showed no association between vitamin D levels and thyroid peroxidase antibody (TPO-Ab) positivity.
What was the takeaway message from the Kmiec and Sworczak article?
The authors concluded that no final word on a correlation could be made. It was neither an absolute ‘yes’ nor a definitive ‘no’. They reported:
“…in many points accumulated data are inconclusive, many unresolved questions remain, therefore, it remains necessary to perform further studies that would affect clinical approaches to thyroid disease.”
They went on to state that the idea of vitamin D supplementation being able to influence the levels of antibodies in Hashimoto’s was also inconclusive:
“Moreover, vitamin D supplementation has not affected disease occurrence in intervention studies, as summarized in 2 recent reviews. The associations between vitamin D deficiency and disease may indicate that 25(OH)D is only a marker of ill health ([Theodoratou et al. 2014]; [Autier et al. 2014]).”
Fast forward a few years, and what does the research reveal on whether there is a connection between vitamin D and Hashimoto’s thyroiditis?
Anaraki, et al. (2017) found no association between vitamin D levels and Hashimoto's thyroiditis.
Boyuk et al. (2016) also reached the same conclusion of no correlation between vitamin D and Hashimoto's thyroiditis.
In 2018, Botelho, et al. reviewed several studies conducted around the world between 2012 and 2016 that basically led to the findings that an association between vitamin D and Hashimoto’s Thyroiditis “…remain unresolved in literature”.
Some of these included:
D' Aurizzio, et al. (2015) No differences in vitamin D deficiency in Hashimoto's thyroiditis patients and healthy controls
Yasmeh et al. (2016) No association of vitamin D deficiency and Hashimoto’s relative to controls
On the contrary,
Sun et al. (2017) revealed Vitamin D levels were inversely correlated with positive TPO-ab and higher D levels were linked to lower TSH in males.
Ma et al. (2015) found that there were lower levels of D in Hashimoto's thyroiditis patients relative to controls.
Wang et al's. (2015) meta-analysis of twenty studies and the Mazokopakis et al. review (2014) also corroborated with Ma’s conclusion that there is an association.
Bozkurt et al. (2013) found a direct relationship between vitamin D and Hashimoto's thyroiditis. He and his colleagues looked at 180 Hashimoto's thyroiditis patients and 180 controls and found that vitamin D levels were significantly lower in the Hashimoto's thyroiditis patients compared to the controls. He and his team concluded that the severity of vitamin D deficiency correlated positively with disease time (duration of Hashimoto's thyroiditis) and higher concentrations of anti-thyroid antibodies, suggesting a potential role of vitamin D in the development of Hashimoto's thyroiditis and/or its progression to hypothyroidism.
Botelho and colleagues then conducted their own study that included 159 participants whereby there were 88 patients with Hashimoto's thyroiditis, of which 82 were female (93%). In the control group, there were 71 subjects, 61 of which female (85.9%). Mean‐time of diagnosis of Hashimoto's thyroiditis was ten years (range 1– 47 years).
Vitamin D levels below 30 ng/dL were found in 59.1% (n= 39) of the control group and in 71.8% (n= 61) of Hashimoto's thyroiditis group (p= 0.1024).
Botelho and his team concluded that there was no relationship with a clarification:
Lower levels of vitamin D have not been associated with Hashimoto's thyroiditis, however thyroxine levels were determined as a risk factor for vitamin D insufficiency. Additional studies are warranted to clarify the precise role of vitamin D in autoimmune thyroid disease (autoimmune thyroiditis).
Like Botelho and team’s conclusions, Yasmeh et al. (2016) also found that there was no connection between vitamin D and Hashimoto’s. Yasmeh and his colleagues separated his research groups by gender. The levels of vitamin D for the Hashimoto's thyroiditis and control groups among the females were significantly different (51.7% vs. 31.1%); however, there was no significant difference in D levels among the male group. Furthermore, the researchers stated that none of the females were actually deficient in vitamin D in the first place! It’s just that the levels were different between the two female groups (Hashimoto's thyroiditis vs. healthy).
Do we then place emphasis on these two recent studies by Botelho and Yasmeh that show no connection between vitamin D and Hashimoto’s? What did other more recent studies and meta-analyses reveal?
Bakr and Meawed (2017) did find an association between vitamin D and Hashimoto’s thyroiditis. There is not only a positive correlation between the vitamin and autoimmune thyroiditis but also an inverse correlation with thyroid antibodies (anti-TGB and anti-TPO).
Kim (2017) reviewed twenty studies through 2016 and concluded that most studies have shown an association between low vitamin D status in the pathogenesis of autoimmune thyroid diseases, especially Hashimoto’s. He did note, however, “there are only few preliminary interventional studies for Hashimoto's thyroiditis. Further randomized controlled trials are needed to determine whether there is a causal relationship, and investigate the potential application of vitamin D in the treatment of autoimmune thyroiditis.”
Some of the studies he reviewed included the following four:
Evliyaoglu et al. (2015) The prevalence of vitamin D deficiency in Hashimoto's thyroiditis patients was significantly higher than that in the control group. Blood levels of vitamin D in the Hashimoto's thyroiditis group was significantly lower compared to the control group. Hashimoto's thyroiditis was observed 2.28 times more frequently in individuals with vitamin D levels <20 ng/mL.
Kim (2016) concluded that vitamin D insufficiency was significantly more prevalent in 369 patients with autoimmune thyroiditis than in the 407 without autoimmune thyroiditis and higher among the 221 patients with Hashimoto's thyroiditis than in those with Graves' Disease or non-autoimmune thyroiditis.
Among Hashimoto's thyroiditis cases, patients with overt hypothyroidism had a significantly higher prevalence of vitamin D insufficiency and lower vitamin D levels compared with those with euthyroidism and subclinical hypothyroidism or those without autoimmune thyroiditis. Blood levels of vitamin D were significantly negatively correlated with thyroid-stimulating hormone (TSH) levels after adjustment for age, sex, body mass index, and sampling season. This study had an excellent sample size.
Mansournia et al. (2013) found a significant inverse association between vitamin D levels and Hashimoto's thyroiditis such that each 12.5 nmol/L increase in vitamin D level resulted in a 19% decrease in the odds of Hashimoto's thyroiditis.
Unal et al. (2014) demonstrated that 254 newly diagnosed Hashimoto's thyroiditis patients had lower vitamin D levels than 124 healthy controls and vitamin D levels were inversely correlated with anti-thyroglobulin (Tg) and anti-thyroid peroxidase (TPO) antibodies.
Delving further into the research conducted in recent years, and looking beyond those studies that were included in Kim’s meta-analysis, here were other study conclusions drawn that point to a positive correlation between vitamin D levels and Hashimoto’s thyroiditis:
Maciejewski et al. (2015) revealed that serum vitamin D is significantly lower in Hashimoto's thyroiditis patients vs. controls. He and his colleagues suggested that vitamin D deficiency is one of the risk factors for Hashimoto’s thyroiditis development.
Lionitris and Mazokopakis (2017) concluded that there is an association between vitamin D deficiency and the pathogenesis of Hashimoto’s thyroiditis but also thyroid hypofunction and autoimmunity in general. In summary, the research team’s data demonstrate the association of vitamin D deficiency with Hashimoto's thyroiditis pathogenesis, thyroid hypofunction and autoimmunity overall.
Sonmegoz et al. (2016) studied a group of 136 Turkish children and determined that the prevalence of a vitamin D deficiency was higher in subjects with Hashimoto’s disease (76%) compared to controls (35%).
