Undereating & Thyroid Health
The thyroid affects virtually every function in your body, and it is impacted strongly by nutrient status. Macronutrients (carbs, fat, and protein) and micronutrients (vitamins and minerals) are needed in order to keep your thyroid happy and healthy. Not eating enough to fuel your thyroid can lead to dysfunction, yet you have the power to restore thyroid status with proper re-nourishment.
By: Anya Rosen
Many people are unaware that nutrition and thyroid function are closely intertwined. Undereating deprives the body of essential nutrients. This wreaks havoc on a person’s thyroid, and therefore harms their overall health. Below is an overview of what the thyroid is, how it works and why it matters. The importance of macro and micronutrients on thyroid health will help explain why properly fueling your body is essential for someone’s wellbeing and overall health status.
What Is The Thyroid And How Does It Work?
The thyroid is a butterfly-shaped gland in your neck. It is part of a feedback control loop in the neuroendocrine system. Below is a description on how the thyroid works:¹
The hypothalamus (part of your brain) secrets thyrotropin releasing hormone (TRH).
The pituitary gland (also located within the brain) responds to TRH by synthesizing and secreting thyroid stimulating hormone (TSH).
TSH acts on the thyroid to stimulate synthesis and secretion of thyroid hormones: mostly thyroxine (T4) with some triiodothyronine (T3).
T4 and T3 attach to thyroid-binding globulin protein (TBG) to travel via blood to various tissues.
T4 is converted to T3 or reverse T3 (RT3, the inactive form), which both compete for binding sites on target cells.
T4 and T3 control the secretion of TRH and TSH by negative feedback to maintain proper levels of thyroid hormones in the body.
This mechanism is known as the hypothalamus-pituitary-thyroid (HPT) axis. In hypothyroidism, circulating T4 and T3 levels drop. This signals the pituitary to produce more TSH in order to restore levels. In hyperthyroidism, the opposite occurs.
Why Does Thyroid Health Matter?
Thyroid health is extremely important because T4 and T3 regulate your body’s metabolism. Metabolism includes processes where the energy from food is transformed and used as fuel. You can compare metabolism to a generator, using raw energy from macronutrients to power your body.² This controls virtually all body functions including: heart rate, body temperature, brain development, nervous system responses, digestion, and more.
In addition to T4 and T3, the thyroid gland produces a hormone called calcitonin.² Calcitonin is involved in calcium and bone metabolism. Proper thyroid function is necessary for bone maintenance. Bone health is extremely important, as bone loss (or osteoporosis) can lead to life-threatening fractures.
There are many negative signs and symptoms associated with thyroid dysfunction. Too little thyroid hormones (hypothyroidism) can cause: fatigue, cold sensitivity, constipation, dry skin, weight gain, puffy face, hoarseness, muscle weakness, elevated blood cholesterol, muscle aches, joint pain, menstrual cycle irregularities, thinning hair, slowed heart rate, depression, impaired memory, and/or enlarged thyroid gland.³ Overproduction of thyroid hormones (hyperthyroidism) is associated with: unintentional weight loss, rapid or irregular heartbeat, palpitations, increased appetite, nervousness, tremors, sweating, menstrual cycle irregularities, heat sensitivity, more frequent bowel movements, enlarged thyroid gland, fatigue, muscle weakness, difficulty sleeping, skin thinning, and brittle hair.⁴ As you can see, thyroid dysfunction takes a toll on your entire body, both inside and out.
Macronutrients & Thyroid Health
Macronutrients (protein, fat and carbs) play critical roles in thyroid function. They matter because they provide energy (calories), and adequate energy is needed for proper thyroid function. The body responds to eating too little calories by down-regulating bodily processes, including the production of thyroid hormones.⁵ This can result in a condition called euthyroid sick syndrome, also known as nonthyroidal illness syndrome. Euthyroid sick syndrome usually presents with low T3, normal-low T4, and normal-low TSH.⁶
Among the macronutrients, carbohydrates are especially important in regulating T3 production. This is likely related to low insulin levels associated with low-carbohydrate diets.⁵ Low-carbohydrate diets have also been linked to higher levels of cortisol, the stress hormone.⁷ The additional stress on the adrenals can disrupt the hypothalamus pituitary adrenal (HPA) axis, which in turn can cause HTP axis dysregulation.¹ However, carbohydrates are not the only macronutrient that matters. Insufficient dietary protein intake has also been linked to HPT dysfunction.⁸ Meanwhile, sufficient dietary fat is essential for energy homeostasis required for normal thyroid function. Simply put: in order to take care of your thyroid, you need to consume enough calories via a balanced diet including protein, fat and plenty of carbs.
Micronutrients & Thyroid Health
Micronutrients (vitamins and minerals) are also essential for proper thyroid status. One of the most important micronutrients when it comes to thyroid health is iodine. Iodine is a mineral that is one of the main constituents of T3 and T4. Iodine deficiency is one of the most common causes of hypothyroidism globally.⁹ The main source of iodine in our diet comes from iodized salt, and it is also found in some seafood and sea vegetables like seaweed and kelp. Unless your doctor or dietitian has advised you to limit your salt intake due to specific health conditions (such as high blood pressure or kidney disease), it is important to utilize iodized salt when possible. If salt is iodized, it will say so on the product container (Hint: that fancy himalayan sea salt is not iodized).
Another important micronutrient for the thyroid is selenium, which is also a mineral. Selenium is needed to activate and inactivate thyroid hormones, and it is found in enzymes that protect the thyroid from damage by free radicals.¹⁰ Brazil nuts, seafood, meat, cereals and other grains, and dairy products are all good sources of selenium, which is why avoiding food groups can contribute to thyroid dysfunction.
In addition to iron and selenium, there are many other nutrients that are needed by the thyroid to do its job. These include iron, zinc, vitamin E, B vitamins, vitamin C, vitamin D, vitamin A, and more.¹⁰ These vitamins and minerals are necessary for proper production of thyroid hormones, increase conversion of T4 to T3, and improve cellular sensitivity to thyroid hormones. The best way to ensure that you are getting all of the micronutrients that you need is not only to eat a variety of foods, but to also eat enough of it.
Your thyroid dictates how you feel and function. Great nutrient status is essential for thyroid health. Limiting your food intake results in macro and micronutrient deficiencies, which contributes to thyroid dysfunction. Eating an adequate amount of food from a variety of food groups is necessary to keep your thyroid - and thus, your body - running optimally.
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This post was written by BALANCE Intern, Anya Rosen.
Anya is a Dietetic Intern and has completed her Master’s in Clinical Nutrition at New York University. Meanwhile, she is also getting certified as an Integrative Functional Nutrition practitioner, and she is an NASM certified personal trainer. She completed her undergraduate degree in Math & Computer Science at Dartmouth College and worked in tech and consulting for a few years. However, health and wellness has always been her passion. After seeing so many men and women (including herself) struggle with it, she decided to go back to school and make it her career. Her goal is to apply her knowledge, experience and compassion to practice truly individualized, evidence-based patient care.
References
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