The Surprising Connection Between Your Gut and Your Thyroid

Recently the microbiome has been found to influence the health of all many other organs of the body, so it’s not surprising it affects hormone balance. However, so close is the connection between the gut and the thyroid that scientists have coined a new term: the gut/thyroid axis.

• Immune Function

Over two-thirds of your immune function sits in your gut, with the bacteria in your microbiome dictating how well your immune system functions. So, any disturbance to your microbiome leaves you with an increased risk of autoimmune diseases. Hashimoto’s thyroiditis is inflammation of the thyroid caused by immune system cells mistakenly attacking it instead of an invader. This damages the gland and it can’t produce sufficient thyroid hormones to go around. Up to 90% of low thyroid issues in adults are thought to be down to the immune system going rogue.

• Inflammation

Research has discovered the bacteria in the guts of people suffering from thyroid disorders are different to those of healthy people, with certain species being more plentiful while others are scarcer. Their bacterial ratios in people with thyroid issues were similar to those seen in sufferers of metabolic diseases like Type 2 diabetes.

In fact, the connection is so strong researchers have suggested measures of bacterial balance in the gut could be used to diagnose people at risk of developing thyroid disease.

Some bacteria naturally found in your gut manufacture substances called short-chain fatty acids by fermenting fibre from plant foods. These play major roles in helping your gut communicate with the rest of your body, as well as regulating inflammation. The types of gut bacteria in people with hypothyroidism tend not to be very good at making these fatty acids.

• Leaky Gut

A healthy microbiome creates a healthy intestinal lining. If the bacteria in your microbiome is unbalanced, the lining of your intestines can become too permeable. When this happens, toxic substances are absorbed into your bloodstream, initiating a chain of events leading to inflammatory molecules travelling to your thyroid gland.

• Hormonal Control

The bacteria in your microbiome affect the metabolism of thyroid hormones, including converting the hormones into their active form. This applied to hormones produced by your thyroid gland itself as well as those given as medication.

Once thyroxine has been processed by your liver it’s transported to your intestines. Gut bacteria can latch onto the thyroxine and store it, providing a hormone reservoir to reduce blood fluctuations of thyroxine.

• Mineral Absorption

Unbalanced gut bacteria reduce the absorption of minerals essential for your thyroid. These include iodine, iron and copper, needed to make thyroid hormones, and zinc and selenium, important for converting thyroid hormones to their active form.