The Gut-Thyroid Connection

February 12, 2023

The Gut-Thyroid Axis is a well-known and growingly recognized connection between the gut and thyroid, where the two are interdependent. This connection has gained attention as a significant factor in health and disease, as thyroid and gut issues often co-occur, such as autoimmune thyroid diseases and celiac disease.

The thyroid, located in the front of the neck below the larynx, is a butterfly-shaped gland that produces hormones that regulate the body's metabolic processes, digestion, heart function, mood, brain development, and muscle control. Thyroid conditions include goiter, thyroiditis, hyperthyroidism, hypothyroidism, Graves disease, thyroid cancer, thyroid nodules, and thyroid storm.

The gut, also known as the digestive system, includes the stomach, small and large intestine, liver, pancreas, and gallbladder and plays crucial roles in digestion, nutrient absorption, immune function, mood regulation, and hormone regulation. The gut microbiome, composed of trillions of microbes including bacteria, yeast, fungi, and parasites, can be impacted by factors such as diet, medication, environment, and genetics.

When the gut microbiome is imbalanced, known as dysbiosis, it can negatively impact various aspects of health including the immune system, mental health, and physical health. This imbalance has been linked to various illnesses such as inflammatory bowel disease, chronic fatigue syndrome, and thyroid diseases like Hashimoto's thyroiditis and Graves' disease.

Gastrointestinal symptoms of thyroid dysfunction include trouble swallowing, heartburn, indigestion, reduced acid production, nausea or vomiting, gallbladder complaints, abdominal discomfort, gas, bloating, diarrhea, constipation, and general digestive complaints including Irritable Bowel Syndrome.

Thyroid hormones like thyroxine (T4) and triiodothyronine (T3) play key roles in regulating functions such as conception, sleep patterns, mental health, energy levels, and digestion, absorption, and assimilation of food and nutrients. This is because these hormones define basal metabolism throughout the body, particularly in the intestine and internal organs.

Stress, which can come in various forms, produces more cortisol (stress hormone), which may reduce T3 levels (the active thyroid hormone). Inflammation in the gut, whether due to dysbiosis, immune response, or gastrointestinal disease, increases cortisol levels and if prolonged, can have a negative effect on T3 levels.

It has been well documented and researched that thyroid and digestive issues often coexist, with the liver being the most affected organ in both hyper- and hypothyroidism. The gastrointestinal manifestations of thyroid disease are typically due to reduced motility in hypothyroidism, increased motility in hyperthyroidism, autoimmune gastritis, or oesophageal compression by a thyroid process.

In conclusion, the gut and the thyroid are closely linked, and a healthy gut is crucial for healthy thyroid function. Poor gut health can impair thyroid function, and vice versa, which highlights the importance of maintaining a balanced gut microbiome.


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