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Hashimoto’s thyroiditis is the most common cause of hypothyroidism in developed countries. It is ten times more common in women than in men and is especially common in women who are between forty-five and fifty-five years old (McLeod & Cooper, 2012). Hashimoto’s is an autoimmune disorder, which essentially means that the body starts attacking its own cells instead of foreign “invader” cells. Hashimoto’s manifests when the immune system begins targeting the thyroid, causing chronic inflammation. Over time, these repeated attacks on the thyroid decrease its ability to produce hormones and can lead to an underactive thyroid.
THE THYROID AND ITS HORMONES
The thyroid is a butterfly-shaped gland in the front of the neck. You may not think twice about your thyroid, but it’s responsible for releasing hormones that regulate metabolism and affect hunger, sleep, and body temperature. Thyroid disorders can increase or decrease the thyroid’s production of these hormones. This creates metabolism issues that can throw our whole body out of whack and can cause weight and mood changes.
When the thyroid is working properly, the brain produces thyroid stimulating hormone (TSH), which signals to the thyroid that it should begin releasing hormones. Within the thyroid gland, the enzyme thyroid peroxidase (TPO) then synthesizes the two most important thyroid hormones: triiodothyronine (T3) and thyroxine (T4). T3 is the active hormone, and T4 is converted in various tissues to T3 as needed. If the immune system attacks the thyroid, as it does in Hashimoto’s, then anti-TPO antibodies and other antithyroid antibodies will interfere with thyroid hormone creation and disrupt the delicate feedback system between the brain and the thyroid.
PRIMARY SYMPTOMS OF HASHIMOTO’S
Hashimoto’s develops slowly and can go unnoticed for several months or even years. Symptoms include fatigue, sensitivity to cold, constipation, pale skin, brittle nails, hair loss, swollen tongue, muscle aches, depression, and memory issues (NIH, 2017). Since symptoms such as fatigue, weight gain, or depression are not necessarily unique to the disorder, many people may not seek treatment. Others may have no recognizable symptoms. If the thyroid gland eventually becomes severely swollen, a visible lump called a goiter develops.
What’s the Difference between Hypothyroidism and Hyperthyroidism?
Hypothyroidism with an o refers to a decrease in thyroid hormones and thyroid functionality. Hyperthyroidism with an er refers to an increase in thyroid hormone production and an overactive thyroid. Symptoms of hypothyroidism include fatigue, constipation, sensitivity to cold, and/or a puffy face. Symptoms of hyperthyroidism include appetite changes, rapid weight loss, difficulty sleeping, heart palpitations, increased sweating, and/or irritability. The most common cause of hypothyroidism in developed countries is Hashimoto’s thyroiditis; in underdeveloped countries, the most common cause is iodine deficiency. The most common cause of hyperthyroidism is the autoimmune disorder Graves’ disease.
Potential Causes and Related Health Concerns
Hashimoto’s is likely caused by an interplay of genetics and environmental factors. While the specifics are not entirely known, some researchers believe Hashimoto’s may be largely caused by infections, while others think the issue is exposure to endocrine disruptors.
People with Hashimoto’s are at risk of having high cholesterol and other co-occurring autoimmune disorders.
GENETICS
Genetics seem to be the biggest player when it comes to a person’s risk of developing Hashimoto’s. Scientists are working to explain how environmental factors may interact with our genes to trigger autoimmune disorders. More than a million gene variants have been identified, thanks to ongoing efforts from several large studies, such as the 1000 Genomes Project, which analyzed thousands of people’s genomes from around the world. Scientists have found that several immune-regulating genes are associated with Hashimoto’s. And new therapeutic drugs to target these genes can be designed to treat Hashimoto’s and other autoimmune diseases.
THE HYGIENE HYPOTHESIS
Several autoimmune diseases have been shown to be associated with the number of infections a person had as a child (Bloomfield, Stanwell-Smith, Crevel, & Pickup, 2006). This phenomenon is called the hygiene hypothesis: The more germs you are exposed to early in life can increase your body’s ability to protect you against certain allergies and immune conditions as an adult. But if you were more of a germ-free kid, you may be at higher risk for certain diseases as an adult. There isn’t consistent evidence that this is the case for Hashimoto’s.
The reverse may also be true—that the presence of certain infections may trigger thyroid inflammation, causing Hashimoto’s to develop (Bloomfield et al., 2006; Mori & Yoshida, 2010): Research suggests that certain infections, such as hepatitis C or Epstein-Barr virus, may trigger individuals to develop autoimmune disorders, especially if they have an underlying genetic susceptibility (Janegova, Janega, Rychly, Kuracinova, & Babal, 2015; Kivity, Agmon-Levin, Blank, & Shoenfeld, 2009; Shukla, Singh, Ahmad, & Pant, 2018).
So it seems that some infections as a child might protect you from autoimmune disease by bolstering your immune system (the hygiene hypothesis), while other, specific types of infections (such as hepatitis C or Epstein-Barr) could create autoimmunity.
ENDOCRINE DISRUPTORS
More and more evidence is piling up against phthalates, BPA, and parabens, showing that these chemicals are able to disrupt our body’s hormone system. This can create a wide array of issues related to reproduction, development, and thyroid function. These chemicals are used in many different products, from cosmetics to canned food, plastic bottles, and children’s toys.
HIGH CHOLESTEROL
One related health concern of Hashimoto’s is high cholesterol, which is associated with adverse cardiovascular health and events (NIH, 2017). While most doctors recommend statins for people with high cholesterol, this is not recommended for people with hypothyroidism who are using hormone replacement medications, since these drugs generally already decrease cholesterol levels.
AUTOIMMUNE DISORDERS
People with other autoimmune disorders, such as celiac disease, lupus, type 1 diabetes, and rheumatoid arthritis, are more likely to develop Hashimoto’s (NIH, 2017).
How Hashimoto’s Is Diagnosed
To diagnosis Hashimoto’s, doctors will want to consider family medical history and symptoms. While the exact cause of Hashimoto’s is not known, it does tend to run in families. Additionally, doctors will want to do a confirmatory blood test to determine levels of TSH, T4, T3, and anti-TPO antibodies. High levels of TSH and anti-TPO antibodies along with low levels of the thyroid hormones T3 and T4 are consistent with Hashimoto’s.
However, individuals who are diagnosed early may only show high antibody levels on their blood tests. If you suspect that you may have Hashimoto’s, ask your doctor for a blood test to see if your thyroid antibodies are high, which is usually the first sign. Some doctors may treat Hashimoto’s if just TSH levels are high, while others may want to also see evidence of antibodies and disrupted thyroid hormone levels, too. It depends on what type of specialist you see and how they approach treatment. Normal TSH levels are typically around 0.4 to 4.9 milliunits per liter, but levels depend on the lab technique used, so be sure to talk to your doctor about your results.
Dietary Changes
You may want to avoid gluten and “goitrogenic” foods, which are believed to affect the thyroid. Ketogenic diets may also not be right for people with Hashimoto’s.
AUTOIMMUNE PROTOCOL (AIP) DIET
To combat inflammation from autoimmune conditions, a restrictive diet called the Autoimmune Protocol (AIP) diet has more recently been recommended by some functional medicine doctors. This diet eliminates inflammation-causing foods and is similar to a paleo diet. The diet is very restrictive: You do not eat grains, legumes, dairy products, processed foods, refined sugars, industrial seed oils (canola or vegetable oil), eggs, nuts and seeds, nightshade vegetables, gum, alternative sweeteners, emulsifiers, or thickeners.
GLUTEN AND CELIAC DISEASE
People with and without celiac disease are turning toward gluten-free diets and foods. Celiac disease is an autoimmune disease, like Hashimoto’s, where the body targets the small intestine after gluten is eaten. And new research shows that celiac and Hashimoto’s might be related. Celiac patients have highly sensitive immune systems, may not absorb key nutrients (like iodine, selenium, and iron), and have lots of antibodies that may affect both the intestine and thyroid (Liontiris & Mazokopakis, 2017; Roy et al., 2016; Sategna-Guidetti et al., 1998). Preliminary research suggests that people with Hashimoto’s should be screened for celiac and that a gluten-free diet may be helpful in managing symptoms (Krysiak, Szkróbka, & Okopień, 2018; Lundin & Wijmenga, 2015).
KETOGENIC DIETS
Ketogenic diets have become popular for weight loss. But they aren’t great for everyone, and research suggests that they probably are not good for people with Hashimoto’s. Ketogenic diets are low-carb, high-fat diets. The goal is for your body to switch out of sugar-burning mode and into fat-burning mode. This is called ketosis. Since ketogenic diets essentially mimic starvation, they may not be desirable for people whose thyroids are already functioning suboptimally, because the diet could further disrupt their metabolism. Several small studies have suggested that when carbohydrate intake is reduced, T3 levels decrease (Bisschop, Sauerwein, Endert, & Romijn, 2001; Hendler & Bonde III, 1988; Spaulding, Chopra, Sherwin, & Lyall, 1976). These were short-term studies of individuals without hypothyroidism, so the results may not be applicable, but they suggest that carbs may be an important food group for people with Hashimoto’s.
GOITROGENS
Goitrogens are foods that are believed to cause “goiter”—swelling of the thyroid gland—and affect thyroid hormone production. Some goitrogenic foods are soy milk, green tea, cassava, rutabaga, some forms of millet, and green leafy vegetables (Bajaj, Salwan, & Salwan, 2016; Chandra & De, 2013; Fort, Moses, Fasano, Goldberg, & Lifshitz, 1990; Paśko et al., 2018). These foods may cause problems for people who are deficient in thyroid-specific nutrients (read the following section), but little is known about how they interact with the thyroid or whether eliminating them has any effect on Hashimoto’s.
Nutrients and Supplements for Hashimoto’s
IODINE
Iodine is a trace element found in foods such as seafood, dairy, produce, and enriched grains (NIH, 2019a). It is a vital component of the thyroid hormones and is absolutely essential for a healthy thyroid. Iodine deficiency used to be an epidemic in the United States before iodized salt and fortification programs were introduced, and iodine deficiency is still a public health issue in other countries. Iodine deficiency can create serious problems, such as hypothyroidism, and during pregnancy it’s the number one preventable cause of mental retardation worldwide (NIH, 2019a). The Recommended Dietary Allowance (RDA) for adults is 150 micrograms, and for pregnant and lactating women it is 220 and 290 micrograms (NIH, 2019a).
While iodine deficiency has historically been an issue, too much iodine has been associated with thyroid dysfunction. It seems counterintuitive, but studies have suggested that autoimmune hypothyroidism and thyroid antibodies may be more common in areas with higher iodine intake (Laurberg et al., 1998). In Japan, for example, where iodine intake from seaweed is very high, numerous studies have shown a high prevalence of thyroid dysfunction (Konno, Makita, Yuri, Iizuka, & Kawasaki, 1994; Michikawa et al., 2012). Also, kelp is high in iodine and consumption of kelp or kelp supplements have been shown to result in cases of hyperthyroidism, hypothyroidism, or iodine-induced thyroid toxicity (Di Matola, Zeppa, Gasperi, & Vitale, 2014; Eliason, 1998; Miyai, Tokushige, & Kondo, 2008; NIH, 2019a).
How Much Iodine Is Too Much?
Although the US Food & Nutrition Board determined that it’s safe to consume up to 1,100 micrograms of iodine (NIH, 2019a), some studies have shown that even small increases in iodine intake, even if consumption is well below the 1,100-microgram threshold, are associated with hypothyroidism (Bjergved et al., 2012; NIH, 2019a; Pedersen et al., 2011; Zhao et al., 2014). One suggested mechanism behind these findings is that excess iodine may promote apoptosis (cell death) of thyroid cells (Xu et al., 2016). While average levels may be okay for most people, there may be some people who are more sensitive to iodine.
In general, nutrition tends to be about balance; too much or too little of a nutrient may cause issues. You may want to consult a doctor to determine if your iodine levels are optimal and if your diet needs any changes to increase or reduce your iodine intake. The safest way to go with supplements is to be moderate. Look at the label and stay close to around 100 percent DV instead of 1,000 percent DV. You may also want to avoid kelp snacks and supplements if you have Hashimoto’s.
SELENIUM
Selenium is also a major player in thyroid function. It is an antioxidant and anti-inflammatory nutrient that is needed to remove iodine from thyroid hormones in order to activate and deactivate the hormones (Liontiris & Mazokopakis, 2017; St. Germain, Galton, & Hernandez, 2009).
Two large cross-sectional studies in France and Germany showed that higher selenium was associated with less goiter and less tissue damage, but only among women; men did not see these benefits in the study (Derumeaux et al., 2003; Rasmussen et al., 2011). Selenium supplementation may help combat the inflammatory and immune responses characteristic of Hashimoto’s. Some research has shown that selenium can decrease anti-TPO antibodies (Fan et al., 2014; Reid, Middleton, Cossich, Crowther, & Bain, 2013; Toulis, Anastasilakis, Tzellos, Goulis, & Kouvelas, 2010; van Zuuren, Albusta, Fedorowicz, Carter, & Pijl, 2014; W. Wang et al., 2018).
IRON DEFICIENCY
Studies have shown that iron deficiency and thyroid problems sometimes occur together (Erdal et al., 2008; M’Rabet‐Bensalah et al., 2016). Remember our thyroid enzyme TPO? TPO needs adequate iron in order to synthesize thyroid hormones. And in one small study, improving iron levels helped with thyroid symptoms (Rayman, 2018). However, it is not clear whether iron deficiency causes thyroid dysfunction or thyroid dysfunction causes iron deficiency (Szczepanek-Parulska, Hernik, & Ruchała, 2017). Researchers hypothesize that people with Hashimoto’s may be more prone to iron deficiency due to a higher occurrence of other autoimmune disorders, such as celiac disease, which results in poor absorption of nutrients (Rayman, 2018; Roy et al., 2016; Sategna-Guidetti et al., 1998). Studies also have shown that pregnant women who are iron-deficient (not an uncommon scenario since growing a baby uses up lots of iron) may be at higher risk for hypothyroidism (Zimmermann, Burgi, & Hurrell, 2007).
VITAMIN D
While you may know that vitamin D is good for your bones, you may not know that it also regulates our immune system. And recent research suggests that it may play a role in the development of several autoimmune disorders (Yang, Leung, Adamopoulos, & Gershwin, 2013).
A study in Europe showed that vitamin D deficiency was more common in individuals with autoimmune thyroid diseases, and low vitamin D was associated with more antibodies and abnormal thyroid function tests (Kivity et al., 2011). Among children, higher vitamin D levels were associated with fewer thyroid antibodies (Camurdan, Döğer, Bideci, Celik, & Cinaz, 2012). However, other studies have shown inconsistent results (Effraimidis, Badenhoop, Tijssen, & Wiersinga, 2012; Goswami et al., 2009). The jury is still out on whether vitamin D supplementation is useful for those with autoimmune disorders such as Hashimoto’s (Antico, Tampoia, Tozzoli, & Bizzaro, 2012; Talaei, Ghorbani, & Asemi, 2018). But in the meantime, it’s a fact that vitamin D is important healthwise, so you want to be sure your levels are optimal.
Our bodies can also produce vitamin D after exposure to the sun’s rays, so getting a daily dose of sunshine, without a layer of sunscreen, helps. This is about moderation; it’s never a good idea to get a sunburn.