Dr. Michael Ruscio, DC is a clinician, Naturopathic Practitioner, clinical researcher, author, and adjunct professor at the University of Bridgeport. His work has been published in peer-reviewed medical journals and he speaks at conferences around the globe.
You Can Keep Both Glands Healthier By Improving Your Microbiome
The thyroid and parathyroid glands are close together in the body and their functions can impact on one another.
Both glands are involved to some degree in calcium regulation, though the thyroid is most often associated with metabolism.
When the thyroid is underactive you are at higher risk of hyperparathyroidism.
When the parathyroid is overactive you are at higher risk of an underactive thyroid.
Balancing your gut microbiota with dietary changes and probiotics can keep both glands healthy.
Gut dysbiosis may be associated with altered levels of thyroid and parathyroid hormones, perhaps by increasing the leakiness of the gut and activating the immune system.
I’ve written a lot about thyroid health in recent months as it’s been a big area of research focus for the clinic. I also produced our patient-focused Thyroid Self Help Course, because the functional health field doesn’t always serve individuals with thyroid symptoms very well.
Though well-meaning, there’s a tendency for functional practitioners to go down the rabbit hole of lab tests, supplements, and getting too into the weeds with hormones, rather than actually focusing on the individual and their symptoms.
For this article, however, I’m going to pivot to consider the parathyroid gland. Glands and organs in the body rarely work totally independently of each other, and the thyroid and parathyroid are no exception.
We’ll examine the relationship between the thyroid and parathyroid, and their dual connection with gut health.
Let’s start by defining and distinguishing between the two glands.
What Do the Thyroid and Parathyroid Glands Do?
The thyroid gland is a butterfly-shaped gland found in the neck, composed of right and left lobes. The thyroid produces the hormones thyroxine (T4) and triiodothyronine (T3) when stimulated to do so by another hormone called thyroid stimulating hormone, or TSH.
The primary role of the thyroid is to keep your metabolism working efficiently.
The parathyroid glands are two pairs of pea-sized glands that are situated in close proximity to the back of each thyroid lobe in the neck. The parathyroid hormone gland produces parathyroid hormone, or PTH.
The primary role of the parathyroid is to help maintain your blood calcium levels within the narrow limits that are critical to health.
While the two organs differ in their primary functions, they actually both have to do with controlling calcium levels. The parathyroid glands secrete PTH to prevent blood calcium levels from dropping too low, while the thyroid gland secretes the hormone calcitonin to prevent blood calcium levels from becoming too high [1, 2]. In other words, the thyroid and parathyroid glands work in a checks and balances duo to maintain normal blood calcium levels.
In this article we’ll address mainly parathyroid rather than thyroid conditions (for some starter general thyroid health articles, see here and here)
Before going into more depth, here’s a quick glance guide to the roles of the thyroid and parathyroid, their interconnectedness, and what can go wrong.
Most Common Thing to go Wrong
How The Glands Interact
Thyroxine (T4) and triiodothyronine (T3). These are produced when told to do so by another hormone (produced by the pituitary) called TSH, or thyroid stimulating hormone
Controls how much energy your body uses (your metabolic rate)
Hashiomoto’s thyroiditis — an autoimmune attack on the thyroid, which leads to an underactive thyroid
When the thyroid is underactive due to autoimmunity you may be at a higher risk for hyper-parathyroidism
Parathyroid hormone (PTH)
Controls the level of calcium in the blood
Hyperpara-thyroidism — too much PTH is produced, and blood calcium levels rise
Higher PTH levels have been linked with suppressed TSH and an underactive thyroid
A Closer Look at Hyperparathyroidism
Hyperparathyroidism is when there is overproduction of PTH by the parathyroid gland, leading to high blood calcium levels. Symptoms include [3, 4]:
Excessive thirst and urination
Osteoporosis and osteopenia (decreased bone density or bone loss)
Primary hyperparathyroidism occurs when one or more of the parathyroid glands become enlarged, producing excess PTH. Usually, the enlargement is caused by a benign tumor called an adenoma. An adenoma is more common in women, particularly postmenopausal women.
Primary hyperparathyroidism occurs in less than 1% of the general population, but in 3.4% of postmenopausal women according to one study [5, 6].
Secondary hyperparathyroidism occurs due to another disease that first causes low calcium levels in the body. Over time, increased parathyroid hormone levels occur as the body fights to keep the calcium level up in the correct range. Causes of secondary hyperparathyroidism include chronic kidney disease or severe calcium or vitamin D deficiency [3, 7].
What About Hypoparathyroidism?
Less common than hyperparathyroidism is hypoparathyroidism (one estimate suggests for every 34 cases of hyperparathyroidism there is one case of hypoparathyroidism) .
As the name suggests, hypoparathyroidism is when your parathyroid glands produce too little PTH. It may result from an autoimmune condition, or through damage to the thyroid glands during thyroid surgery.
If you have hypoparathyroidism, your blood calcium levels fall, with consequences that can include :
Dry and scaly skin
Brittle nails and coarse hair growth
Painful muscle cramps and muscle spasms, especially in the back and legs
Tingling and muscle weakness
Confusion, memory loss, depression, and hallucinations
Irregular heart rhythm (arrhythmias) and congestive heart failure
How the Thyroid And Parathyroid Glands Impact Each Other
Because the thyroid and parathyroid glands are located in such close proximity to each other, physical damage to one can impact on the functioning of the other.
As already mentioned, surgery to remove part or all of the thyroid gland can damage the parathyroid glands and cause hypoparathyroidism. More specifically:
Up to one-third of patients who undergo thyroidectomy will have at least temporary hypoparathyroidism .
4% of patients can have permanent hypoparathyroidism following thyroidectomy .
Treatment of thyroid cancer and goiter with radioactive iodine therapy has also been shown to result in temporary parathyroid gland dysfunction [12, 13].
The thyroid and parathyroids are also linked physiologically, meaning that a parathyroid issue makes it more likely that you will also have a thyroid issue and vice versa. For example, it’s been shown that:
People with an underactive thyroid due to autoimmune disease (Hashiomoto’s thyroiditis) are more likely to have hyperparathyroidism . Evidence from one study suggests that the rate of primary hyperparathyroidism in Hashimoto’s disease patients may be around six times higher than that of the general population .
High levels of parathyroid hormone (PTH) can suppress the production and release of thyroid-stimulating hormone (TSH). One small study found that 52% of patients with hyperparathyroidism that required parathyroid removal also had thyroid disease, including benign thyroid nodules, goiter, and hypothyroidism .
This all goes to say that, for these important glands to function optimally, their health should be addressed together.
For example, gut dysbiosis, or an imbalance of gut bacteria, appears to be linked with Hashimoto’s thyroiditis (underactive thyroid) and Graves’ disease (overactive thyroid), both of which are autoimmune conditions [3, 4].
One theory is that dysbiosis creates gut leakiness in the gut lining, allowing antigens to enter the bloodstream and stimulating autoimmune illnesses, including thyroid autoimmunity .
Research also suggests that certain gut bacteria may be involved in the metabolism of thyroid hormones, with imbalances in gut bacteria potentially leading to alterations in thyroid hormone levels [5, 6].
Gut microbiota health also seems to impact parathyroid health, with studies finding that gut dysbiosis may be associated with altered levels of parathyroid hormone (PTH) and calcium [7, 8]. Gut bacteria may also play a role in the regulation of vitamin D, which is important for parathyroid function .
From recent animal studies and in vitro research, it appears that a healthy gut microbiota additionally plays a role in promoting a healthy response to PTH, resulting in better bone health .
Conversely, animal studies indicate that gut dysbiosis may promote the activity of certain immune cells implicated in autoimmune disease, which may contribute to bone loss .
3 Ways to Promote a Healthy Microbiome
It’s important to note that more research is needed to fully understand the relationship between gut health and thyroid and parathyroid function.
However, creating an environment in the gut that encourages healthy bacteria and discourages unhealthy bacteria can only help. Often, just improving your diet and lifestyle alone will balance the microbiome.
Three of the most impactful changes to improve your microbiome include changing your diet, taking probiotic supplements, and doing exercise.
A diet that is anti-inflammatory, takes into account any food intolerances, and balances your blood sugar will also be good for your good bacteria.
Food intolerance, specifically lactose intolerance, can have particular relevance when it comes to thyroid and parathyroid health. That’s because lactose intolerance can contribute to calcium deficiency and lead to serious health consequences such as osteoporosis , which, in part, may be due to an increase in PTH following impaired calcium absorption and low blood levels.
In addition, two studies showed lactose restriction and a gluten-free diet led to significant decreases in TSH levels for Hashimoto’s patients taking synthetic thyroid hormone. Both studies suggest that food sensitivities can impair the gut’s absorption of thyroid medication [19, 20]. If you need to make healthier changes to your diet but don’t know where to begin, I usually recommend the Paleo diet as a good place to start.
The paleo diet is anti-inflammatory, nutrient-rich, and not overly restrictive. Many people find it has enough carbs and prebiotics to stimulate good bacteria but not so many that it promotes an unhealthy overgrowth of bacteria.
If you are particularly sensitive to carbohydrates or have pre-existing SIBO (small intestine bacterial overgrowth), a Paleo diet might contain more prebiotics than you can handle, however. In this case, a low FODMAP diet may be more helpful.
Triple probiotic therapy is a therapeutic, multistrain approach that we developed in the clinic through years of trial and error with prescribing probiotics. It includes validated probiotic strains from these three major probiotic categories:
Lactobacillus & Bifidobacterium species
Saccharomyces boulardii (a probiotic fungus)
Bacillus species (soil-based probiotics)
While multistrain probiotics haven’t been directly studied for thyroid and parathyroid health, we know from the research that multistrain probiotics can be more effective for various conditions [21, 22, 23]. Using a combination of the above strains will likely give you the most health benefits.
Supplementation with probiotics has also shown to benefit thyroid hormones and thyroid function specifically .
With regards to parathyroid health, one meta-analysis of studies in women over 50 found that probiotics beneficially altered markers of bone health including blood calcium, urinary calcium, and PTH levels . The full clinical implications are unclear at this time, but it is an interesting finding that supports the link between having a healthy microbiome and parathyroid health.
You can also eat probiotic foods like kimchi, kefir, sauerkraut, and kombucha, but you would need to eat a lot of these foods to amount to the same probiotic power as a high-quality supplement.
Physical activity doesn’t just make you fitter and help with weight management — it has a significant impact on the digestive system and your gut microbiome.
The results from one observational study and nine clinical trials found that increased physical activity or fitness was positively associated with higher bacterial diversity and certain short-chain fatty acids (linked to better gut health) in stools .
Longer-term exercise has the biggest effect, so try to find something you enjoy so you can keep it going.
The Thyroid and Parathyroid Are Both Important
The thyroid gland and thyroid disorders get a lot of focus, but let’s not forget about the parathyroid too, as if one isn’t functioning right it can tend to have an impact on the other.
You can underpin the health of both glands with gut supports including diet, probiotics, and exercise.
Thyroid and parathyroid disorders can have consequences if left untreated, so do seek medical attention if you experience symptoms that might suggest either is out of balance.
Another resource that might be useful is the step-by-step guide to better gut and general health detailed in my book Healthy Gut, Healthy You.
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