3 Ways Gut Bacteria Can Harm Your Thyroid

Today, approximately 30 million people are struggling with a thyroid problem and many more are undiagnosed. Women are much more affected by thyroid problems, compared to men, with one out of eight impacted in their lifetime and the likelihood increases as you age. Alarmingly, while most cancer diagnoses are on the decline over the past decade, thyroid cancer rates have been increasing. The obvious question to ask is why are thyroid conditions becoming so commonplace? Like most chronic and degenerative conditions it's multi-factorial, and one key factor affecting your thyroid health is your gut bacteria, also known as the microbiome.

When you’re born into the world, the bacteria that you are exposed to as a newborn set the tone for shaping your microbiome, the trillions of “good” and “bad” gut bacteria that live in your digestive tract (and on your body). Important is the microbiome to your health? Consider a few facts; nine out of every 10 cells on your body is from bacteria and the overwhelming majority of the DNA on your body comes from the bacteria in your gut and on your body (and only 1% from mom and dad). The latest research suggests that it’s the interaction between the two that heavily influence your health and vitality.

Your microbiome plays a key role in supporting optimal thyroid function; balancing blood sugar, cooling chronic inflammation, supporting immunity and converting thyroid hormones.

Your thyroid gland is effectively a bellwether for overall health, signaling a problem in some other area of the body. It’s like the lights on the dashboard of your car, your thyroid alerts you to a problem somewhere else in the body. Therefore, when your microbiome gets out of balance, your thyroid gland will be negatively affected, resulting in poor cognitive function, low mood, sluggish metabolism, poor energy levels… the list goes on and on.

What common factors can cause an imbalance in gut bacteria? The following is a quick list of common aggravators;

·      Western diet (i.e. high carb and processed carbs)

·      Excessive sugar intake

·      Being overweight (or obese)

·      Over-use of antibiotics

·      High chronic stress levels

·      Over-use of stomach acid lowering drugs

·      Birth control pills

·      Gluten consumption

·      Lack of exercise

·      Excessive high-intensity exercise

Unfortunately, conventional medicine treats only the symptoms, like placing duct tape over the warning light (so you can’t see it anymore). It doesn’t address the fundamental question of “why” your microbiome (and thyroid) are out balance in the first place.

3 Gut:Thyroid Connections

Your diet plays a fundamental role in shaping your microbiome, the bacteria in your gut playing a massive role in supporting optimal thyroid health. Let’s take a closer look at what happens when your microbiome gets out of balance.

1)    Gut Bacteria & Blood Sugars

Recently, researchers made a major discovery with respect to the impact your microbiome has on your blood sugar response to meals. Let me explain. The glycemic index (GI) is a measure of how quickly the sugars from the food you eat get into your bloodstream. In general, the more slowly and steadily your blood sugar levels rise (i.e. low-GI foods) and the better off you’ll be in terms of health and body composition. Conversely, high-GI foods will rapidly increase blood sugars and the blood sugar hormone insulin, leading to increased likelihood you’ll store more of the “excess energy” as body-fat, as well as new research showing it leads to poor cardiovascular and cognitive health in the long-term.

A recent study decided to test the GI-index hypothesis by testing different people - over 800 people fit and overweight subjects - with the same exact foods (i.e. low, medium or high-GI foods). In theory, the GI-index of a food (i.e. an apple) should be very similar for all individuals. However, in practice researchers found markedly different blood sugar response to exactly the same foods.(1) Overweight subjects eating low-GI snacks were exhibiting very large blood sugar spikes, and thus, the authors concluded the gut bacteria was exerting a significant impact on blood sugar response from person to person.

In short, your gut bacteria play a major role in your blood sugar response to food (regardless if it’s a “healthy” choice). This has major trickle down effects on your thyroid because big blood sugars swings lead to energy crashes and a subsequent over-reliance of caffeine and sugar for energy. Blood sugar and insulin dysfunction is a major underlying cause of thyroid dysfunction and restoring a healthy balance of gut bacteria is crucial for stabilizing blood sugars.

2)    Microbiome & Chronic Inflammation

If your microbiome is out of balance you’ll likely struggle with consistent bouts of gas, bloating, constipation (or loose stools) and digestive discomfort. An imbalance of “good” to “bad” gut bacteria – known as dysbiosis in medical terms - can wreak havoc on thyroid function because it can trigger a low-grade and systemic inflammatory response by your immune system. Your gut is home to over 80% of your immune system and inflammation is its first response to an insult or damage.

Chronic inflammation throws off your thyroid function in a couple of ways. First, inflammation ignites a fire in your brain (upstream of your thyroid gland), dampening the message from your brain to your thyroid to produce thyroid hormone.(2) This results in low TSH output from the brain, and thus low T4 output by your thyroid. The less thyroid hormone your body makes, the less energy every single cell in your body receives. (No wonder you’re tired).

Next, inflammation impairs thyroid hormone conversion downstream of your thyroid at the tissue level.(3) The fires of low-grade inflammation wear out the receptors at a the tissue level, much like fraying the charger connector on your iPhone, once it no longer fits, you can’t recharge your phone. Similarly, your body can’t recharge its cell and convert T4 into the active T3 hormone.

3)    Microbiome & Thyroid Hormone Conversion

One of the most overlooked aspects of thyroid health is the conversion of thyroid hormone. Your T4 hormone (i.e. thyroxine) made by your thyroid gland, must be converted to the “active” T3 (i.e. triiodothyronine) thyroid hormone to exert its positive effects in your body. If you can’t convert T4 into T3 effectively, you won’t reap the benefits of healthy thyroid function, such as a clearer mind, better mood, quicker metabolism, healthy bowel function, healthy skin and hair, the list goes on and on.

Once again, dysbiosis and an imbalanced microbiome is a major roadblock to thyroid hormone conversion. In fact, 20% of your T4 thyroid hormone is converted to the active T3 form in the gut, therefore if struggle with regular gas or bloating, constipation or consistent discomfort then chances are you’ll have poor conversion.(4) In short, if your digestive system isn’t running smoothly, your thyroid won’t likely be either.

How To Re-Establish A Healthy Gut Microbiome

If you look at modern hunter-gatherer tribes, like the Hadza in southern Africa that mimic our Paleo ancestors, you see stark differences in gut bacteria compared to Western men and women. The Hadza gut microbiomes have much greater bacterial diversity and richness compared to ours in America, Europe, or other industrialized countries.(5) A recent study compared the microbiomes of Western children to those living in rural areas of north Africa where exposure to sugar and a Western diets is non-existent. Researchers found incredible contrasts in bacterial diversity between Western and rural African children. The Western children’s microbiome was predominantly made up of a family of bacteria called firmicutes (fer-MI-cue-tees), whereas the rural African children’s microbiome was made up of primarily the bacteroidetes family (and little firmicutes) and robust diversity of “good” gut bacteria.(6) Excessive firmicutes is problematic because its capable of synthesizing sugars at a rate of 100x more than other bacteria. When levels are high, typically due to consuming too much sugar or processed carbohydrate, you’re more likely to develop dysbiosis and possibly more likely to struggle with thyroid dysfunction.

Your diet is the fundamental player in establishing your microbiome. When you’re struggling with dysbiosis, mimicking our hunter-gatherer ancestors is a great place to start to turn things around. Here is a short-list of nutritional interventions to start the process of rebuilding a healthy microbiome;

1)    Remove all added sugars

2)    Remove all processed carbs

3)    Reduce daily carb intake (if following a moderate to high carb diet)

4)    Eliminate all caffeine

5)    Eliminate all alcohol

6)    Limit fruit (berries are typically best)

7)    Add small amounts of fermented foods (if it aggravates your condition, discontinue)

8)    Achieve at least 25g of fiber per day

9)    Add a soil-based probiotic daily

It may seem daunting to make so many changes, but fear not, a few weeks or months (if you’ve been struggling for some times) is typically sufficient to reshuffle the balance of healthy gut bacteria and start reversing thyroid dysfunction. Get started with these simply tips and your brain, body and thyroid will thank you for it.

Dr. Marc Bubbs ND, CISSN, CSCS