The Internet is awash with all sorts of dietary advice for how a person with hypothyroidism should eat. In this blog post, I’ll explore the claims made about diet and hypothyroidism and see what diet changes, if any, someone with this condition should look at making.
Our thyroid gland plays a key role in metabolism, growth and development. The thyroid gland secretes thyroid hormone which regulates a role range of body processes. The extensive list includes fat and carbohydrate metabolism, respiration, body temperature, brain development, cholesterol levels, the heart and nervous system, blood calcium levels, menstrual cycles, skin integrity, and more. So, you can see just how many potential problems can arise if things go wrong with thyroid hormone production.
The condition of hypothyroidism is where the thyroid gland doesn’t make enough thyroid hormone. There are many causes of hypothyroidism. But there is no question of just how common it is with potentially one in ten Australians demonstrating some form of presentation of it. From a spectrum of the presence of thyroid autoantibodies in the blood right through to overt hypothyroidism.
Hypothyroidism causes and symptoms
The most common cause of hypothyroidism in the western world is Hashimoto’s thyroiditis – also called Hashimoto’s disease. Hashimoto’s thyroiditis is an autoimmune disorder that causes chronic inflammation in the thyroid gland. Hashimoto’s thyroiditis is named after the Japanese surgeon who discovered it in 1912.
Hashimoto’s thyroiditis primarily affects middle-aged women but can occur in men and women of any age and even in children. The cause of Hashimoto’s disease isn’t entirely known. Some scientists believe a virus or bacterium might trigger the inflammatory response. While others believe there is a genetic explanation.
The most common symptoms of Hashimoto’s disease include:
- Weight gain
- Fatigue and sluggishness
- Feeling cold
- Poor memory (also called a brain fog)
- Joint and muscle pain
All these symptoms are related to the function of thyroid hormone. So, it is no surprise that inadequate thyroid hormone causes so many problems.
Removal of the thyroid gland will also cause hypothyroidism if not enough replacement thyroid hormone medication is taken. Radiotherapy to the head and neck area is also a cause.
Then there are diseases that affect the pituitary gland that can also cause hypothyroidism. The pituitary gland is important because it releases thyroid-stimulating hormone (TSH). TSH travels to the thyroid gland to tell it to make more thyroid hormone, and which accelerates iodide uptake by the thyroid gland. Iodide is after all a key mineral that is synonymous with the thyroid gland with a deficiency of this nutrient causing goitre. When thyroid hormone levels are low, TSH secretion is increased so a key blood test for hypothyroidism are TSH levels.
Now back to Hashimoto’s disease considering this is the main cause of hypothyroidism. The disease process for Hashimoto’s is on a spectrum, and not all people with it need treatment. Some people have autoimmune antibodies for the thyroid gland but keep enough thyroid function without the need for medical intervention. Once the body can no longer produce an adequate amount of thyroid hormone, thyroid replacement medication is needed to correct the hormonal imbalances linked with hypothyroidism.
The principal treatment approach of hypothyroidism is to take oral thyroid hormone medication. Usually with a drug called levothyroxine. Levothyroxine is converted to active thyroid hormone in the body.
Diet is important in managing hypothyroidism, but diet alone is not a cure for hypothyroidism. And a side note here: if you’re taking levothyroxine, it should be taken between meals. That’s because some foods and potentially even coffee can reduce its absorption, as too can calcium and iron supplements.
Left unmanaged or when not taking enough thyroid hormone medication, hypothyroidism can lead to many health problems. These problems include weight gain, fatigue, poor memory and hair loss. So, hypothyroidism, whether clinically diagnosed or perhaps even sub-clinical where it hasn’t been fully detected yet, gets a lot of blame for many health problems.
Hypothyroidism and weight gain
Weight gain is a common issue with hypothyroidism. That’s because of thyroid hormone’s direct impact on metabolism. But before even addressing weight gain, the number one priority is to get the hypothyroidism under control. And this is the role of your doctor through blood tests and appropriate medical treatments where needed. Weight changes are very unlikely to happen before all of that is under control.
I don’t have the magic answer for long-term weight loss and anyone claiming they have the solution is selling you bullshit. All diets, no matter what their claims, work by either restricting the volume of food you eat, the time you eat or restrict one of the major macronutrients of either fat or carbohydrate. That’s it. Every diet ever promoted in the history of humankind falls into one or more of these three categories no matter how much they may dress up the rationale with lots of sciencey sounding language. Losing weight and keeping it off is hard. And it is just as hard, perhaps even more difficult, if hypothyroidism is a confounding issue.
In the world of weight loss for hypothyroidism, the ever-popular low-carb diet comes up. But a word of caution here. Some research has found that when taken to the level of a ketogenic diet, it can impact on thyroid hormone levels by limiting the conversion of thyroxine to the active form of thyroid hormone (called triiodothyronine or T3 for short). You can find a nice summary of this research here.
A similar situation of less thyroid hormone production is seen during prolonged fasting. That makes sense since a decline in metabolism during fasting is an adaptive survival response. Because a ketogenic diet mimics some aspects of starvation, then it may not be so favourable for thyroid hormone levels – the complete opposite of what someone with hypothyroidism wants to see.
Should you go gluten free?
Another piece of diet advice that will pop up for anyone delving into the world of diet and hypothyroidism is to cut out gluten. Certainly, in coeliac disease, the response to gluten is a classic autoimmune response. But it has been proposed that even non-coeliac gluten sensitivity (NCGS) could be a trigger for hypothyroidism. I should add that NCGS is a vexed issue of if it is a real condition or just a collection of symptoms that have some overlap with coeliac disease but aren’t related.
Because Hashimoto’s disease is also an autoimmune disease, could there be a link with gluten? There is some overlap with the presence of thyroid antibodies and the presence of coeliac disease so it can’t be discounted completely.
Some studies find that a gluten-free diet can reduce thyroid antibodies, but other studies find no benefit. Certainly, some people have reported significant weight loss simply by switching to a gluten-free diet. But people have reported weight loss on every single diet ever promoted so these are just anecdotes.
The summary here is that if you’ve been diagnosed with Hashimoto’s thyroiditis, then it is worth considering getting tested for coeliac disease rather than just adopting a self-styled gluten-free diet. A true gluten-free diet has far more to it than just cutting out bread and pasta. At this stage, gluten can’t be entirely ruled out as having a link with Hashimoto’s disease. But it is unlikely to be a major contributor in most cases. And that should be clear from the demographics of Hashimoto’s in that women are far more likely to develop it than men so that can’t be explained just by gluten.
Iodine and the thyroid
I couldn’t do a blog post about hypothyroidism without mention of iodine. Iodine is a vital nutrient and essential to thyroid function seeing as it is made up of iodine. While autoimmune disease is the primary cause of thyroid dysfunction and hypothyroidism, iodine deficiency is a key cause of it worldwide.
A severe iodine deficiency during pregnancy causes an extreme and irreversible form of mental and physical retardation known as cretinism. Cretinism affects approximately 6 million people worldwide and can be averted by the early diagnosis and treatment of maternal iodine deficiency. A worldwide effort to provide iodised salt to people living in iodine-deficient areas is ongoing. It’s also why iodine has been added to salt as part of mandatory food fortification in Australia.
Another thing that comes up when learning about hypothyroidism and what role diet can play are things called goitrogens. Goitrogens are substances that can interfere with the uptake of iodine into the thyroid gland and can exacerbate iodine deficiency. Foods high in goitrogens include soy, cassava, and cruciferous vegetables such as cabbage, broccoli, and cauliflower.
For people who get adequate iodine in their diet and eat a variety of foods the consumption of reasonable amounts of foods containing goitrogens is of little concern. Although, science is yet to clearly define what a ‘reasonable amount’ here is. So, it is more of an issue if you have iodine deficiency (or are at risk of it) and have a diet low in iodine. In that case, you may want to not go overboard with these types of goitrogen foods.
When it comes to thyroid function, soy often comes up as a food to avoid for anyone with hypothyroidism. At least that is what the Internet will tell you. Soy does contain goitrogens, but a review of 14 studies in healthy adults AND people with hypothyroidism found little effect of soy foods on a range of measures of thyroid function. Still, the authors did state that there does remain a theoretical concern based on cell culture and animal studies that in people with compromised thyroid function or low levels of iodine consumption, that soy foods may increase the risk of developing clinical hypothyroidism. But just whether they should avoid soy foods altogether or just limit them is unclear.
For anyone with thyroid problems, don’t get your diet advice from what you read on the Internet from ‘wellness’ blogs and the like, especially if it is prefaced by alarmist claims about soy and other ‘goitrogen’ foods that have little basis in scientific fact. And especially with the case of Hashimoto’s disease where the underlying cause could be nothing to do with iodine deficiency hence there is little need to go on a restrictive goitrogen avoidant diet.
The final nutrient I’m going to cover is selenium. Selenium is found in high quantities in the thyroid gland and is required to produce enzymes that regulate thyroid hormone metabolism. Given its critical role, some think that selenium levels could influence the development of Hashimoto’s disease. But this claim is controversial because a specific mechanism has not been discovered.
A meta-analysis of randomised, placebo-controlled studies has shown the benefits of selenium supplementation on both thyroid antibody levels and mood in people with Hashimoto’s disease. But the effect seems to be greatest in those with a selenium deficiency to start with which perhaps is not that surprising. And a follow-up review to this study published in Cochrane Reviews also found mixed evidence to either support or refute the use of selenium supplementation in people with Hashimoto’s thyroiditis.
A word of warning. Selenium is not a nutrient to just dose yourself up on without good reason as too much of it can cause gastrointestinal and nervous system problems. And there have even been cases of death caused by taking supraphysiologic amounts of it. Good food sources of selenium include Brazil nuts, seafood, meats and wholegrains.
What it all means
So, let’s wrap this up. There really isn’t any kind of standout ‘hypothyroid diet’ that would be recommended for someone with Hashimoto’s disease. Instead, it is about broad healthy eating guidelines that can be tweaked if there is a greater reason to focus on more foods containing selenium or iodine or perhaps trialling a period on a gluten-free diet for a time.
Losing weight and maintaining it is difficult for anyone regardless of if there is an underlying medical condition or not. The two best predictors of success here are sticking to the dietary changes that connect with a person and getting ongoing help, support and advice. Be wary of dogmatic advice that weight loss is only possible on low-carb, low-GI, Paleo, intermittent fasting or any number of other popular diets – there is no ‘best diet’ for weight loss.
That doesn’t mean that someone with Hashimoto’s shouldn’t be open to trying different eating styles until they find the one that makes them feel better. But the cornerstone of the management of hypothyroidism rests with your doctor and someone like a dietitian to get tailored nutrition and lifestyle advice. That is a much better starting place than dubious advice from the Internet that makes promises of miraculous results for curing hypothyroidism just by hacking your diet.