When I consult with someone who has Graves’ Disease or Hashimoto’s Thyroiditis, it’s common for the person to have a family history of thyroid disease. However, I also work with a lot of patients with an autoimmune thyroid condition who don’t have a family history of thyroid autoimmunity, or any other autoimmune conditions for that matter. The National Institutes of Health estimates that up to 23.5 million Americans suffer from autoimmune disease, and that the prevalence is rising, while the American Autoimmune Related Diseases Association (AARDA) claim that the number is closer to 50 million (1) . And of course there are tens of millions of people in other countries who suffer from Graves’ Disease, Hashimoto’s Thyroiditis, and other autoimmune conditions. But why is there an increased prevalence of autoimmunity?
Before discussing some of the different reasons for the increased prevalence of autoimmune thyroid conditions, as well as other autoimmune conditions, it’s important to point out that there is a genetic component behind most, if not all of these conditions. And the reason why this is important to mention is because in all likelihood the genetic predisposition hasn’t changed over the last 50+ years, but there is no question that over the last few decades our environment has changed for the worse. And if we don’t modify these environmental factors, not only will you not improve your health and therefore will remain more susceptible to developing other autoimmune conditions, but if you have children then there is an increased likelihood that they will develop an autoimmune condition.
So let’s go ahead and discuss some of the main reasons why thyroid autoimmunity is on the rise:
1. Increased C-sections and bottle feeding. Having a Cesarean section changes the gut microbiota, as does bottle feeding. And so being born via a C-section and/or being bottle-fed can make you more susceptible to developing an autoimmune condition in the future. Children born via a C-section lack the benefit of protective vaginal bacteria, which may make them more susceptible to viruses, allergies, and asthma later in life, as well as type one diabetes (2)  (3) . Another study showed that being born via a C-section increases the risk of developing Celiac disease (4) . As for the importance of breast milk, human milk differs from formula not only with regards to nutrients, but it also has growth factors, cytokines, immunoglobulins, and digestive enzymes that are lacking in infant formula (5) . Yet another study showed that formula-feeding is associated with a shift towards Th1 cytokines, which may have an influence on the development of autoimmune disease (6) . It’s worth noting that Hashimoto’s Thyroiditis is usually a Th1-dominant condition.
Of course I realize that sometimes C-sections are necessary, and the same is true with bottle feeding. But many C-sections are unnecessary, and some mothers don’t breastfeed their babies because they find it more convenient to bottle feed. Another factor is that many women aren’t aware of the health benefits of breastfeeding, although I realize that most women reading this are probably aware that breastfeeding is a healthier option. Of course I understand that some women do want to breastfeed their babies but are unable to, but the point I’m trying to make is that thousands of women are able to breastfeed their babies but choose not to do so, and most of these women don’t realize the negative impact this can have on the future health of their baby.
2. Western diet. A “Western diet” typically includes foods that are high in sugar, unhealthy fats and oils, are frequently processed, etc. And the reason why eating poorly can increase the risk of developing an autoimmune condition is because such diets promote inflammation. Obesity is one factor, as this leads to the excessive accumulation of white adipose tissue and systemic inflammation (7) . In addition, processed foods and fast foods usually contain high amounts of salt, which in turn can increase Th17 cells (8)  (9) , which is a factor in autoimmune conditions. In addition, Western diets will result in significantly different microbiota compositions, and one reason is because these diets are typically low in the fiber necessary to feed the good bacteria (10) . One study mentioned that a Western diet creates a specific inflammatory environment in the gut (11) , and as many people reading this know, in order to have a healthy immune system you need to have a healthy gut. A Western diet usually involves the excess consumption of omega 6 fatty acids, which also will promote inflammation. And let’s not forget the negative impact that gluten can have on the gut.
3. Environmental toxins. Over the past few decades there have been tens of thousands of chemicals manufactured. One of the most well known ones is bisphenol a (BPA), which not only is an endocrine disruptor, but may play a role in the development of autoimmune conditions (12)  (13)  (14) . Phthalates are added to plastics to make them more flexible and harder to break, and they are found in adhesives, cosmetics, fragrances, vinyl flooring, polyvinyl chloride pipes, and certain toys and medical supplies (15) . And there is evidence that phthalates can trigger autoimmunity (15) (16) . Vaccines are also a possible factor (17)  (18) , and while this remains controversial, one thing that’s not debatable is that infants and children today receive many more vaccines than they did a few decades ago. And of course there are many other environmental toxins we are exposed to, and to be honest, it would be shocking if there wasn’t an increase in autoimmunity with the stress put on our immune system by all of these chemicals.
4. Chronic Stress. Both physical and psychological stress has been implicated in the development of autoimmune disease (19) . Of course humans have always dealt with stress, but the stressors of today are different than the stressors of the past. In the past humans dealt more with acute stress situations, but these days we commonly deal with chronic stress. As for how this can lead to autoimmunity, stress activates the hypothalamic-pituitary-adrenal (HPA) axis, which in turn releases cortisol, and this in turn suppresses the immune system (20)  (21) . However, it is thought that the stress-triggered neuroendocrine hormones cause dysregulation of the immune system, which alters cytokine production, and this in turn leads to autoimmunity (22) . Keep in mind that this is just a theory, as the mechanism isn’t completely understood, but there does seem to be a connection. And of course having an autoimmune condition such as Graves’ Disease or Hashimoto’s Thyroiditis can be very stressful, and so even if someone has an autoimmune thyroid condition that wasn’t triggered by stress, having the condition itself can be stressful, and this chronic stress can perpetuate the autoimmune response.
5. Antibiotics, hand sanitizer, and the hygiene hypothesis. The hygiene hypothesis suggests that exposure to bacteria, viruses, and other “germs” can help improve your immunity. For example, when I was a child my friends and I frequently would play outside in the dirt. In fact, it was unusual for me to come back into the house clean. These days I rarely see this, as it’s more common to see children and teenagers on their electronic devices. In addition to not interacting with the environment, hand sanitizer is frequently used, and this also minimizes our exposure to these “germs”. As a result of being too hygienic this can actually weaken our immune system, and can make us more susceptible to developing chronic inflammatory conditions, including autoimmune conditions.
What can you do about this? Well, I would definitely minimize the use of hand sanitizer and antibacterial soaps. I spoke about this in greater detail in an article I wrote entitled “Triclosan and Thyroid Health “. Of course trying to avoid taking antibiotics is also important, and while there is a time and place for taking these, in many cases these are unnecessary. And if you have children please let them play in the dirt…and feel free to go ahead and get dirty with them!
So hopefully you have a better understanding as to why the incidence of thyroid autoimmunity is increasing, along with other autoimmune conditions. While genetics is no question a factor in the development of autoimmune thyroid conditions, lifestyle and environmental factors are primarily responsible for the increased prevalence. Some of the main reasons for the rise in thyroid autoimmunity include increased number of C-sections, formula feeding, eating a poor diet, greater exposure to environmental toxins, chronic stress, and the hygiene hypothesis.