I regularly read through recent literature on autoimmune thyroid disease/Hashimoto's. I post about each of these studies on instagram as I review them and put it all together on this blog twice per year. 

You can use the categories located to the right of this post and click 'Hashimoto's Research Update' to see all of the updates.

TPO Antibodies and Quality of Life (https://pubmed.ncbi.nlm.nih.gov/21186954/)  (2011)

This study included 426 females who planned to undergo thyroid surgery. They only included participants whose TSH, FT3 and FT4 were in the normal range. TPO antibodies were tested prior to surgery and they examined the thyroid tissue that was removed. These women also took symptom and health questionnaires prior to surgery. 

The researchers found that the level of TPO antibodies correlated with the grade of thyroid inflammation. This makes a lot of common sense, higher antibodies = more thyroid destruction. The following symptoms were found to be higher in the patients with elevated TPO antibodies: chronic fatigue, dry hair, chronic irritability, chronic nervousness, dysphagia, and easily fatigued. Remember, the study participants all have normal thyroid hormone levels. The researchers also found that higher TPO levels were associated with an overall decreased quality of life. 

A patient recently told me that her endocrinologist lamented that Hashimoto’s is so ‘overblown’. This paper was published in 2011. It’s time we start listening to patients AND keeping up with the research. There is nothing overblown about Hashimoto’s and just treating thyroid hormones (TSH, FT3, FT4) isn’t enough for Hashimoto’s patients. We can do better. 

Epstein-Barr virus association with Hashimotos (https://pubmed.ncbi.nlm.nih.gov/32215255/) (2020)

Epstein Barr virus, one of the viruses that cause mononucleosis or ‘mono’, is considered a possible trigger of Hashimoto’s disease. This study investigated the prevalence of different types of antibodies to Epstein Barr virus (EBV) in people with Hashimoto’s thyroiditis (HT) and healthy controls. Approximately 95% of the adult population is infected during their life so not surprisingly, all participants tested positive for the antibody that measures if someone has been infected. What’s interesting is that the amount of antibodies present was significantly higher in the HT patients than in healthy controls. In addition, one of the antibodies, the early antigen IgG which is considered a marker of reactivation of the virus, was positive in HT patients at a significantly higher rate than controls. 

Review of Nutrients Needs In Hashimoto’s (https://doi.org/10.1967/s002449910507) (2017)

This review article published in 2017 provides an update from the literature regarding several key factors impacting Hashimoto’s. I will summarize their findings for each below. 

Iodine: Hashimoto’s is more common in areas that have plenty of iodine in the food supply/soil. Even small increases in iodine intake increase the risk of Hashimoto’s. The authors recommend discouraging excess iodine intake but caution that iodine levels of 250mcg daily are still required for pregnancy. Note from Dr. Barrett: this is a ‘goldilocks’ situation- you still need adequate iodine, just not too much. For non-pregnant patients I recommend limiting total iodine intake daily to 150mcg. 

Selenium: The thyroid tissue contains the highest concentration of the trace mineral selenium in our bodies. This mineral acts as an antioxidant and has anti-inflammatory properties. The exact mechanism of benefit to the thyroid has not been determined but we do know that it seems to modify the immune and inflammatory response. Three meta analyses have confirmed that selenium reduced TPO and TG antibodies. Selenomethionine is superior to sodium selenite because selenomethionine is absorbed more easily. The authors concluded that supplementing with selenomethionine is beneficial for Hashimoto’s patients. 

Vitamin D: This one is pretty straightforward. Vitamin D supplementation improves Hashimoto’s disease. The authors explain that the low cost and low side effect profile of 2,000- 4,000IU of vitamin D daily make it another good candidate to improve Hashimoto’s disease. 

Gluten: The authors argue that according to a recent meta analysis all patients with Hashimoto’s should be screened for celiac disease because of the high association between these two autoimmune conditions. “ In summary, whereas it is not yet clear whether a gluten- free diet can prevent autoimmune diseases, it is worth mentioning that HT [Hashimoto’s Thyroiditis] patients with or without CD [Celiac Disease] benefit from a diet low in gluten as far as the progression and the potential disease complications are concerned”. Note from Dr. Barrett: I think it’s warranted to try the gluten free diet in Hashimoto’s after screening for celiac disease.  

Association of antithyroid peroxidase antibody with fibromyalgia in rheumatoid arthritis (https://doi.org/10.1007/s00296-015-3278-1) (2015)

Hashimoto’s is an autoimmune condition that destroys the thyroid tissue and may lead to hypothyroidism. These two conditions are often lumped together but it’s possible to have Hashimoto’s and not develop hypothyroidism. This study investigated the presence of autoimmune thyroid disease in patients already diagnosed with rheumatoid arthritis (RA). Their aim was to determine if there is an association with chronic widespread pain (CWP) and/or fibromyalgia and autoimmune thyroid disease. Their findings are quite interesting. There is a strong association with the presence of one of the thyroid antibodies and CWP and fibromyalgia but not the other! Only TPO antibodies were associated with the increase in chronic pain in this population. Another interesting finding is that the association of TPO antibodies with fibromyalgia was independent of hypothyroidism. This is important because hypothyroidism can cause widespread pain so the assumption could be made that the association with this antibody and pain could be due to the low thyroid function. That isn’t the case. There is something about the presence of the TPO antibody that is the association with pain. I find these results important because patients are often told once their hypothyroidism is treated, their autoimmune thyroid symptoms should be resolved. This study supports the fact that many patients are still symptomatic even when their thyroid hormones have normalized. The authors conclude that testing for TPO antibody should be standard of care in RA patients to help determine risk of CWP and fibromyalgia. 

The association of other autoimmune diseases in patients with autoimmune thyroiditis (https://doi.org/10.1016/j.autrev.2016.09.009 ) (2016)

The association of other autoimmune diseases in patients with autoimmune thyroiditis: Review of the literature and report of a large series of patients.

This literature review found an increased prevalence of several autoimmune disorders when someone has autoimmune thyroid disease. The most common associations were Autoimmune thyroid disease + chronic autoimmune gastritis + vitiligo and Autoimmune thyroid disease + chronic autoimmune gastritis + polymyalgia rheumatica.

Other conditions that were more common alongside autoimmune thyroid disease include: rheumatoid arthritis, celiac disease, diabetes, sjogren disease, multiple sclerosis, systemic lupus erythematosus, sarcoidosis, alopecia, psoriatic arthritis, systemic sclerosis, and HCV-related cryoglobulinemia

Chronic autoimmune gastritis (CAG)  was the most commonly associated autoimmune disease with autoimmune thyroid disease. CAG is largely asymptomatic and can remain undiagnosed for a long time. Sometimes laboratory results can clue us in such as low iron and or low B12. Some people can feel generalized digestive upset, reflux and/or feeling full early.  CAG is diagnosed with antibody testing (parietal cell and intrinsic factor antibodies) and endoscopy. 


Reference:
1. Ott, Johannes & Promberger, Regina & Kober, Friedrich & Neuhold, Nikolaus & Tea, Maria & Johannes, Huber & Hermann, Michael. (2011). Hashimoto's Thyroiditis Affects Symptom Load and Quality of Life Unrelated to Hypothyroidism: A Prospective Case-Control Study in Women Undergoing Thyroidectomy for Benign Goiter. Thyroid : official journal of the American Thyroid Association. 21. 161-7. 10.1089/thy.2010.0191

2. Assaad SN, Meheissen MA, Elsayed ET, Alnakhal SN, Salem TM. Study of Epstein-Barr virus serological profile in Egyptian patients with Hashimoto's thyroiditis: A case-control study [published correction appears in J Clin Transl Endocrinol. 2020 Dec 17;23:100242]. J Clin Transl Endocrinol. 2020;20:100222. Published 2020 Mar 12. doi:10.1016/j.jcte.2020.100222
 
3. Liontiris, M. I., & Mazokopakis, E. E. (2017). A concise review of Hashimoto thyroiditis (HT) and the importance of iodine, selenium, vitamin D and gluten on the autoimmunity and dietary management of HT patients.Points that need more investigation. Hellenic journal of nuclear medicine, 20(1), 51–56. https://doi.org/10.1967/s002449910507 

4. Ahmad, J., Blumen, H. & Tagoe, C.E. Association of antithyroid peroxidase antibody with fibromyalgia in rheumatoid arthritis. Rheumatol Int 35, 1415–1421 (2015). https://doi.org/10.1007/s00296-015-3278-1
​
5.  Poupak Fallahi, Silvia Martina Ferrari, Ilaria Ruffilli, Giusy Elia, Marco Biricotti, Roberto Vita, Salvatore Benvenga, Alessandro Antonelli.The association of other autoimmune diseases in patients with autoimmune thyroiditis: Review of the literature and report of a large series of patients. Autoimmunity Reviews. Volume 15, Issue 12 (2016) Pages 1125-1128. ISSN 1568-9972,
https://doi.org/10.1016/j.autrev.2016.09.009 ​

I regularly read through recent literature on autoimmune thyroid disease/Hashimoto's. I post about each of these studies on instagram as I review them and put it all together on this blog twice per year. 

You can use the categories located to the right of this post and click 'Hashimoto's Research Update' to see all of the updates. ​

Vitamin D Treatment in Patients with Hashimoto's Thyroiditis May Decrease the Development of Hypothyroidism (2016)

What if you have elevated thyroid antibodies but your TSH isn’t elevated yet, ie it’s Hashimoto’s Thyroiditis (HT) but not yet progressed to hypothyroidism? Conventionally patients are often told to just watch and wait. Wait until it turns into hypothyroidism, then you can take medication. 

This study published in 2016 demonstrated that supplementing with vitamin D actually reduced thyroid antibodies and prevented the progression of HT into hypothyroidism. So there is something you can do instead of just watch and wait. 


One limitation of this study is that it was performed in Turkey, a country with notoriously low vitamin D levels. The average vitamin D level in patients with HT entering the study was 9 and the control group average was 12! During the study all of the groups raised their vitamin D blood levels to around 50. So it’s important to test your vitamin D levels. If you are already around 50/60 you likely wouldn’t benefit from additional vitamin D supplementation. 


The Composition of Gut Microbiota in Patients Bearing Hashimoto's Thyroiditis with Euthyroidism and Hypothyroidism (2020) 

This study compared the gut microbiome between three groups; normal controls, people with Hashimoto’s but normal thyroid function (HT), and people with Hashimoto’s and hypothyroidism (HTH). This study consisted of 97 people all from a particular region in China. The researchers found that the richness of diversity in the gut microbiome was significantly lower in HT patients than in the control group. The patients with HTH had the least microbial abundance. Our gut microbiome plays a vital role in our immune system so it makes sense that shifts in the microbiome could be playing a role in autoimmune diseases. Something else to consider is that thyroid hormones also influence the function of our GI, especially motility. It’s possible the change in diversity from HT to HTH could be partly due to the influence of low thyroid hormone on GI function. 

This research further confirms why it’s so important to nurture a healthy gut microbiome. 


Psychological Wellbeing in Hashimoto’s (2017) 

The main finding of this study is that health related quality of life is impaired in euthyroid Hashimoto’s patients. Let’s break this down a bit. Euthyroid Hashimoto’s Thyroiditis (HT) is when a patient has thyroid antibodies and/or Hashimoto’s specific abnormalities on thyroid ultrasound but a normal TSH. This study evaluated the quality of life for HT’s patients and found that HT’s patients had lower quality of life regarding physical functioning, general health and mental health. Specifically this study found that patients with euthyroid HT had increased levels of both anxiety and depression. Interestingly, this study included a group of euthyroid HT patients that were taking levothyroxine and a group not taking any medication. There were no differences between these two groups in terms of depression, anxiety or quality of life scores. So medication did not improve these symptoms. 

My patients are consistently told by endocrinologists if they are on medication and their TSH is normal then their symptoms are not from Hashimoto’s. Not true. Evidence is mounting that there are deeper mechanisms here. 

Another nugget from this paper that I have to directly quote, it’s so good! “TSH levels were slightly higher in HT group than control group although all the participants were in euthyroid state in our study. Higher TSH levels were also found in previous studies comparing euthyroid HT and control subjects. These findings might suggest that slightly higher TSH even in the normal range might be related with impairment in psychological well-being in patients with euthyroid HT.” One more time for the folks in the back! HT patients have been fighting to be heard around this issue for such a long time. It’s time to reevaluate the ‘normal’ range for TSH especially in HT patients.  


Effect of Low Carbohydrate Diet in Autoimmune Thyroiditis (2016) 

The title is misleading because they changed a lot more about the diet than just carbohydrate content. The authors removed several common food intolerances (dairy, eggs and gluten) in addition to implementing a low carbohydrate diet. 

Here’s the breakdown: 180 total participants 84 males and 96 females aged 30-45 years. All subjects tested negative for celiac disease (in truth the specific language they use is “all subjects did not present celiac disease” so I am uncertain if they actually tested them or not).

The experimental diet was followed for 3 weeks and included aiming for macro’s of carbs 12-15%, proteins 50-60%, and lipids 25-30%. Foods excluded: goitrogenic foods (unlisted specifically what these were), eggs, legumes, dairy, bread, pasta, fruits and rice. Control group followed a low calorie diet without restrictions on types of food to consume. 

The author referenced goitrogenic foods repeatedly as part of the dietary exclusion but in the materials and methods section these foods were not specifically listed. In the introduction the author discusses goitrogenic foods and states “These substances (known as goitrogens) are found especially in products of the cruciferous (Brassicaceae) family (rape seed or canola, cabbage, turnip, watercress, arugula, radish, horseradish) and in milk produced by cattle nourished with these vegetables. Other goitrogens include soy, spinach, millet, tapioca, and lettuce. Even certain food additives, ie, nitrates used for fish and meat preservation, prevent iodine uptake by the thyroid gland.” So it’s unclear which foods were actually excluded in the experimental group. What is clear is this is not a simple low carb diet analysis. 

The author also put a heavy emphasis on goitrogens and Hashimoto’s. I haven’t seen goitrogen’s make much of a difference clinically with Hashimoto’s patients. Check out this article written by Dr. Alan Christianson for a much deeper dive into goitrogens and Hashimoto’s.  

Bottom line: don’t switch your diet just yet, we need more research on nutrition and Hashimoto’s. This study used too many dietary variables and was very short in duration. 

Oxidative Stress and Hashimoto’s (2014) 

This study is straightforward. The investigators compared biomarkers in people with euthyroid autoimmune thyroiditis (read: Hashimoto’s disease but normal levels of TSH, FT3, and FT4) and people without any thyroid disease. It was a small study with only 70 participants. I appreciate that they looked at a diverse set of biomarkers to assess oxidative stress including oxidized LDL. They controlled for variables that could impact oxidative status such as age, BMI, and fasting glucose. It is not surprising that folks with Hashimoto’s had a decrease in antioxidants and an increase in oxidants vs controls. We have a delicate balance of free radicals (oxidative stress) and antioxidants keeping our bodies healthy. If the scales tip and we are under higher levels of oxidative stress a whole host of disease can occur. Excessive levels of oxidative stress is considered one of the factors underlying the autoimmune response. 

Bottomline: Folks with Hashimoto’s have lower levels of antioxidants and higher oxidative stress. It’s important to consume a diet rich in antioxidants. 





​References: 

1. Ucan B, Sahin M, Sayki Arslan M, Colak Bozkurt N, Kizilgul M, Güngünes A, Cakal E, Ozbek M. Vitamin D Treatment in Patients with Hashimoto's Thyroiditis may Decrease the Development of Hypothyroidism. Int J Vitam Nutr Res. 2016 Feb;86(1-2):9-17. doi: 10.1024/0300-9831/a000269. Epub 2017 Jul 12. PMID: 28697689.
2. Liu S, An Y, Cao B, Sun R, Ke J, Zhao D. The Composition of Gut Microbiota in Patients Bearing Hashimoto's Thyroiditis with Euthyroidism and Hypothyroidism. Int J Endocrinol. 2020 Nov 10;2020:5036959. doi: 10.1155/2020/5036959. PMID: 33224194; PMCID: PMC7673947.
3. Muhittin Yalcin M, Eroglu Altoniova A, Cavnar B, Bolayir B, Akturk M, Arslan E, Ozkan C, Cakir N, Balos Toruner F. Is thyroid autoimmunity itself associated with psychological well-being in euthyroid Hashimoto’s thyroiditis? Endocrine Journal. 2017, 64(4), 425-429
4. Esposito T, Lobaccaro JM, Esposito MG, Monda V, Messina A, Paolisso G, Varriale B, Monda M, Messina G. Effects of low-carbohydrate diet therapy in overweight subjects with autoimmune thyroiditis: possible synergism with ChREBP. Drug Des Devel Ther. 2016 Sep 14;10:2939-2946. doi: 10.2147/DDDT.S106440. PMID: 27695291; PMCID: PMC5028075.
5. Baser, H., Can, U., Baser, S. et al. Assessment of oxidative status and its association with thyroid autoantibodies in patients with euthyroid autoimmune thyroiditis. Endocrine 48, 916–923 (2015). https://doi.org/10.1007/s12020-014-0399-3

Myo-inostiol and Selenium for Hashimoto's (2017)
You might already know that selenium can be very helpful for Hashimoto’s. It’s an antioxidant that supports the production of glutathione. Selenium is helpful in reducing anti TPO antibodies. This study compared patients using selenium alone and selenium with myo-inositol. 

Inositol is involved in cell signaling specifically around TSH, FSH and insulin. You may be familiar with inositol’s benefit for some patients with polycystic ovarian syndrome (PCOS) and it turns out, it’s helpful for patients with Hashimoto’s as well. 

This study found that using 600mg of inositol in combination with selenium was superior to selenium alone in reducing TSH levels and improving thyroid hormone concentration. TPOAb concentration decreased in both groups as expected. TgAb doesn’t tend to reduce with selenium supplementation alone and this study found that when adding myo-inositol there is a reduction in TgAb concentration! Patient’s also reported more symptom improvement when using a combination of selenium and myo-inositol. 

Bottom line: consider talking to your provider about using a combination of selenium and inositol to support your thyroid health.  


Nutraceuticals for Thyroid Health (2020)
This article is a review article which means the authors scoured the literature looking for all the information they could find on the topic. As the title indicates, most studies they looked at and discussed were done in animals. This article is full of great information about nutrients and their role in thyroid health. I am going to summarize some high points-
Vitamin D: Likely plays a protective role in preventing thyroiditis 

Zinc: Positively impacts thyroid function

Selenium: Improves immune regulation

Inositol: This was the topic of last month’s review article, these authors reviewed that study among others that concluded inositol is beneficial in autoimmune thyroid disease. 

Resveratrol: I’ve previously reviewed research exploring the mental health implications of Hashimoto’s disease and it appears that resveratrol might be useful. It improved BDNF and had antidepressant activity in hypothyroid mice. In addition, resveratrol appears to prevent the metabolic toxicity caused by fluoride exposure (drinking water) and restored the functional status of the thyroid. 

Soy: There is no easy answer here. Soy likely has different impacts on human health during various life stages (ie the effects on a baby fed soy formula are different from a perimenopausal person) making animal models unreliable for humans. It also appears that the potential goitrogenic effect of soy is made worse with low iodine in the diet. (My opinion- deciding soy is ‘bad’ for the thyroid and completely avoiding it is a little bit like throwing the baby out with the bathwater. If we took ever food/nutrients that may inhibit thyroid function out of the diet we would have very little left to eat.)

They also reviewed several synergistic reactions which really interests me. It’s not often we find THE ONE nutrient that the body needs to function better. We are complex creatures and nothing works in isolation. They found melatonin’s benefits were improved with zinc, selenium’s benefits were improved with inositol, and vitamin E’s benefit was improved with curcumin. 

There is much more to the article than what I summarized. It’s an open-access article available free online so check it out if you want more details :)


Cognitive functioning in Hashimoto's Patients (2018)
Something I hear at least weekly in practice is, “I am on levothyroxine/synthroid and my doctor says my thyroid is fine but I still have symptoms”. Well that is exactly the outcome from this study. They compared 139 patients with Hashimoto’s Thyroiditis (HT)  who were properly treated with medication and 111 people who do not have thyroid disease. The TSH, FT3 and FT4 were no different between the thyroid patients and controls. You know what was different between the two groups? Symptoms. Global cognitive function, anxiety and depression scores were all significantly worse in the adequately treated HT patients. This isn’t surprising to those of us that treat thyroid disease holistically. Just replacing thyroid hormone doesn’t get to the root of the problem. 

If you have Hashimoto’s and you’ve asked your conventional provider to check your antibodies (TPOAb and TGAb) you have likely been told that antibodies levels don’t matter. Well this study also helps disprove that long-held theory. The researchers found that TPOAb levels correlated with a lower quality of life in hypothyroid patients. 

Bottomline: Just replacing thyroid hormone often doesn’t improve symptoms in Hashimoto’s patients and checking antibody levels is an important part of your care. If your provider isn’t on board, might be time to look for a new one. 


Differences in food consumption between patients with Hashimoto’s thyroiditis and healthy individuals (2020)
I am pleased to see another study evaluating the relationship with food and Hashimoto’s Thyroiditis (HT) but unfortunately this study doesn’t give us very much clinically useful information. 

The most statistically significant results were that folks with HT consumed more animal fat and processed meat that controls. Controls consumed more red meat, grains, plant oils and non-alcoholic beverages. 

There was an association with elevated T3 levels in those who consumed more plant oil. The questionnaire used offered 3 options for fat intake: plant oil, olive oil and animal fat. So unfortunately, ‘plant oil’ covers a variety of oils and this nugget isn’t very helpful. 

This study isn’t clinically useful for a variety of reasons. This is a cross sectional, observational study that is not designed to give a causal connection between the consumption of food groups and HT development. It is also very challenging to accurately measure food intake via questionnaires. Anyone who has filled out or reviewed a diet diary understands this! The questionnaire used in the study was not designed to collect quantitative data on dietary intake, only frequency of intake. If someone eats 1 TBS of animal fat vs 5 TBS of animal fat 3x per week, that’s a big difference and isn’t taken into account in this study. 

Bottomline: Really nothing helpful here to incorporate into practice unfortunately. Again, still happy to see more research on diet and Hashimoto’s disease though!



References

1. ​Nordio M, Basciani S. Myo-inositol plus selenium supplementation restores euthyroid state in Hashimoto's patients with subclinical hypothyroidism. Eur Rev Med Pharmacol Sci. 2017 Jun;21(2 Suppl):51-59. PMID: 28724185.
2. Benvenga S, Ferrari SM, Elia G, Ragusa F, Patrizio A, Paparo SR, Camastra S, Bonofiglio D, Antonelli A, Fallahi P. Nutraceuticals in Thyroidology: A Review of in Vitro, and in Vivo Animal Studies. Nutrients. 2020 May 8;12(5):1337. doi: 10.3390/nu12051337. PMID: 32397091; PMCID: PMC7285044.
   
3. Djurovic M, Pereira AM, Smit JWA, Vasovic O, Damjanovic S, Jemuovic Z, Pavlovic D, Miljic D, Pekic S, Stojanovic M, Asanin M, Krljanac G, Petakov M. Cognitive functioning and quality of life in patients with Hashimoto thyroiditis on long-term levothyroxine replacement. Endocrine. 2018 Oct;62(1):136-143. doi: 10.1007/s12020-018-1649-6. Epub 2018 Jun 29. PMID: 29959689.
   
4. Kaličanin, Dean & Brčić, Luka & Ljubetić, Katija & Barić, Ana & Gračan, Sanda & Brekalo, Marko & Lovrić, Vesela & Kolcic, Ivana & Polasek, Ozren & Zemunik, Tatijana & Punda, Ante & Perica, Vesna. (2020). Differences in food consumption between patients with Hashimoto’s thyroiditis and healthy individuals. Scientific Reports. 10. 10670. 10.1038/s41598-020-67719-7. ​

​I am starting up a new blog series to highlight research updates for Hashimoto’s Thyroiditis (HT). My intention is to review recent literature every 6 months. I am starting by pulling together a variety of research articles until I feel ‘caught up’ (will I ever feel caught up?!) and will then focus solely on new research. My plan  is to publish an update every January and July. 

For this first installment I have pulled together a variety of research articles. 

Gluten and Hashimoto’s (2019)

Krysiak R, Szkróbka W, Okopień B. The Effect of Gluten-Free Diet on Thyroid Autoimmunity in Drug-Naïve Women with Hashimoto's Thyroiditis: A Pilot Study. Exp Clin Endocrinol Diabetes. 2019;127(7):417-422. doi:10.1055/a-0653-7108

I read this article in 2019 when it came out and was excited to see that research is starting to support what we have known clinically for years. Many patients with Hashimoto’s Thyroiditis (HT) benefit from a gluten free diet. The sample size was small and it wasn’t randomized, patients were allowed to choose the gluten free group or the control group. That said, even with the small sample size there was an improvement in both TPO and TG antibodies in the gluten free group as well as a slight increase in thyroid hormone output. 

The authors hypothesize that the improvement in autoimmunity may be due in part to an increase in vitamin D that was seen in the gluten free group. The participants did not increase their vitamin D intake and it’s unknown why a gluten free diet would have improved their vitamin D status. 

This study is very interesting and I hope it’s the first of many exploring the important connection between a gluten free diet and HT. 


Vitamin D and Hashimoto’s (2016 + 2018)

Sahin, M., Corapcioglu, D. The effect of vitamin D on thyroid autoimmunity in non-lactating women with postpartum thyroiditis. Eur J Clin Nutr 70, 864 (2016). https://doi.org/10.1038/ejcn.2016.56

Xu J, Zhu XY, Sun H, et al. Low vitamin D levels are associated with cognitive impairment in patients with Hashimoto thyroiditis. BMC Endocr Disord. 2018;18(1):87. Published 2018 Nov 26. doi:10.1186/s12902-018-0314-7

We know from observational studies that low vitamin D status seems to contribute to thyroid autoimmunity. What sets this research apart is that they looked at women post partum to see what impact vitamin D supplementation has on antibodies. ⁠If you are familiar with Hashimoto's you probably know post partum is a common time for the condition to flare. ⁠
⁠
The investigators found that the women with post partum thyroiditis (PPT) had lower levels of vitamin D than post partum women without thyroiditis. Giving vitamin D (either 2,000IU or 4,000IU depending on the patient's vitamin D blood level) to the PPT women significantly lowered their antibodies without any side effects. Between 20-40% of women with PPT go on to develop permanent hypothyroidism and lowering antibodies is an important step to prevent that outcome.

The second study looks at the relationship between vitamin D, Hashimoto's Thyroiditis (HT), and  cognitive impairment. 
⁠
We already know that low vitamin D is correlated with cognitive impairment in the general population and that there is a high prevalence of low vitamin D in patients with HT. It wasn't surprising that they found low vitamin D is associated with cognitive impairment in patients with HT. ⁠

The authors  also found that vitamin D levels were inversely related to TPO antibody levels.

Bottom line study #1 and #2:  If you have Hashimoto's I highly recommend talking to your provider about your vitamin D level. ⁠
⁠
Depression and Hashimoto’s (2011 + 2014)

Giynas Ayhan M, Uguz F, Askin R, Gonen MS. The prevalence of depression and anxiety disorders in patients with euthyroid Hashimoto's thyroiditis: a comparative study. Gen Hosp Psychiatry. 2014;36(1):95-98. doi:10.1016/j.genhosppsych.2013.10.002

Hardoy MC, Cadeddu M, Serra A, et al. A pattern of cerebral perfusion anomalies between major depressive disorder and Hashimoto thyroiditis. BMC Psychiatry. 2011;11:148. Published 2011 Sep 13. doi:10.1186/1471-244X-11-148

The first study looked at the prevalence of depression and anxiety in euthyroid Hashimoto’s thyroiditis. Euthyroid Hashimotos’ is when a patient has Hashimoto’s but their thyroid hormones are not abnormal (yet!). They looked at patients who have a normal FT3, FT4 and TSH but also have thyroid antibodies and an abnormal thyroid ultrasound. There are already several studies that show a higher prevalence of psychiatric disorders in patients with Hashimoto’s but this study is unique in that they only included HT patients who had ‘normal’ thyroid function based on thyroid hormone testing. Surprise! They found there was a higher prevalence of anxiety and depression in these patients than in the general population or control. There are many theories as to why HT patients have a higher incidence of psychiatric disorders and many center around imbalanced levels of TSH, FT3 and FT4. There is likely more to the story. This study might be the first to find a relationship between OCD and HT. The prevalence of OCD in the HT group was 15.7% and the prevalence in the general population is around 0.8% to 3.2%. 

Bottom line study #1 - If you have anxiety or depression and your thyroid has been screened with just a TSH make sure to talk to your provider about a comprehensive screen that includes antibody or ultrasound testing  especially if you have a family history of thyroid disorders. 

The authors summarized the second study very well so I am going to quote the authors directly “The debate on the pathogenesis of depression in thyroid autoimmunity involves two hypothesis, it is suggested that the neuronal tissue is hypersensitive to hormonal deficiencies and are more vulnerable to possible subclinical hormonal deficiencies not detectable with routine laboratory tests. In the second hypothesis, a possible pathogenic factor linked to inflammation is postulated, consequent to cytokine activation or extraglandular lesions similar to vasculitis induced effects.” 
In other words it could be that our brains are hypersensitive to fluctuations in thyroid hormone so even when the levels are ‘normal’ our brains might suffer and/or there is likely a role of inflammation in altering blood flow. 

Bottom line study #2: Depression and brain blood flow changes happen with HT (both euthyroid and hypothyroid) and patients with depression, especially atypical depression, need comprehensive thyroid screening. 

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