Subclinical Hypothyroidism and Zinc Deficiency

author avatar Dr. Eric Berg 08/31/2023

I want to talk about a really critical contributing factor in subclinical hypothyroidism: zinc deficiency.

Subclinical disease is a medical condition that does not present any noticeable symptoms. Clinical disease, on the other hand, is a medical condition that does present noticeable symptoms. The two terms are often used interchangeably, but there is a subtle distinction between them.

Subclinical disease vs Clinical disease is often asymptomatic, which means that patients may not be aware that they have the condition. Clinical disease, on the other hand, is symptomatic, meaning that patients are likely to experience symptoms such as pain, fatigue, or difficulty breathing.

The term "subclinical" can also be used to describe a condition that is not yet severe enough to be considered clinical.

While other causes of subclinical hypothyroid get a lot of attention, zinc deficiency usually goes unnoticed. That said, the reality is that, without enough zinc, you cannot convert T4 to T3 and you can’t make thyroid hormones. In other words, your thyroid cannot work properly.

In this article, I will cover:

Let’s dive in.


What Is a Subclinical Hypothyroid Problem?

Subclinical hypothyroid - also known as mild thyroid failure - is when you have a slow thyroid but most of your blood values are technically still normal. The only levels that look “off” are your serum thyroid-stimulating hormone (TSH) levels, and these can appear slightly elevated.

If you’re basing things purely only on blood tests, then - and you’re not looking deeper - you can completely miss this condition until it develops into full-blown clinical hypothyroidism.


First Thing’s First: Understanding Healthy Thyroid Function

Before we can understand subclinical hypothyroidism, we have to take a look at normal thyroid function.

The thyroid is ultimately controlled by the hypothalamus, a small structure in the brain that’s responsible for:

  • Releasing hormones
  • Regulating body temperature
  • Maintaining daily physiological cycles
  • Controlling appetite
  • Managing of sexual behavior
  • Regulating emotional responses

The hypothalamus makes a hormone called thyroid releasing hormone (TRH). It also tells the nearby pituitary gland to release a hormone called thyroid-stimulating hormone (TSH). Those hormones then go down to the thyroid and tell the thyroid to produce and release thyroxine (T4) and a little bit of triiodothyronine (T3).

Endocrine system negative feedback loop - TRH, T4, T3

T4 is an inactive thyroid hormone, while T3 is the active version. Both are essential for brain development in infants and for metabolic activity in adults. Specifically, these hormones help the brain, heart, liver, muscles, and other organs of the body function properly. In fact, people with thyroid issues will typically have similar body composition which can be characterized as the thyroid body type.

In order for T4 to work in the body, it has to be converted into T3. This actually works through several organs, including the liver and the kidneys. 80% of T4 is converted through the liver, and 20% is converted through the kidneys to make T3.

Then, T3 goes into all the cells and it affects metabolism and many other things. Once it’s done its job, there’s a signal that’s sent back to the pituitary and the hypothalamus, turning these off. So you have a negative feedback loop.

There are several really important trace minerals involved in thyroid function:

  • Iodine: making the thyroid
  • Selenium: Converting T4 to T3
  • Copper: Involved in the creation of the thyroid hormone
  • Zinc: Zinc is not only involved in the conversion from T4 to T3, but also in the synthesis of T4 and T4, T3, and the thyroid-stimulating hormone that comes from the pituitary down to the thyroid itself.

What Causes Subclinical Hypothyroidism?

The causes and contributing factors to both subclinical and clinical (or overt) hypothyroidism are the same. The most well known causes include:

  • Gender: A study published in the journal Endocrinology and Metabolism showed that women are two to five times more likely to develop subclinical hypothyroidism than men.
  • Age: TSH tends to rise as you age, making subclinical hypothyroidism more prevalent in older adults.
  • Iodine intake: Subclinical hypothyroidism tends to be more prevalent in populations that consume sufficient or excess iodine, a trace mineral essential for proper thyroid function.

Another important possible cause? Zinc deficiency.


The Role of Zinc in the Body

Zinc is necessary for healthy thyroid function

Now, zinc is not usually emphasized, but it’s really important. Overall, zinc is an important trace mineral that’s necessary for a healthy immune system and proper metabolic function. It’s involved in a number of functions in the body, and it helps stimulate the activity of over 100 different enzymes.

As a result, research shows that zinc can help with:

  • Colds: Evidence shows that, if zinc lozenges or syrup is taken within 24 hours after cold symptoms start, the supplement can help shorten the length of colds.
  • Diarrhea: Oral zinc supplements have been shown to reduce diarrhea symptoms in children with low zinc levels.
  • Age-related macular degeneration: Research suggests that the trace mineral may slow the progression of this eye disease.
  • Wound healing: Zinc plays a role in every stage of the wound healing process, helping with cell membrane repair, cell proliferation, growth, and immune system function.

When it comes to thyroid function, zinc is not only involved in the conversion from T4 to T3, but also in the synthesis of T4 and T4, T3, and the thyroid-stimulating hormone that comes from the pituitary down to the thyroid itself.

Currently, the recommended dietary allowance (RDA) for zinc is 8mg for women and 11 mg for men.


Thyroid Problems Caused By Zinc Deficiency

Without enough zinc, you cannot convert T4 to T3 and you can’t make thyroid hormones.

This is particularly important if you’re experiencing things hair loss and alopecia.

If you’re not getting enough zinc in your diet, you can take thyroid hormone and take trace minerals and still not get your hair back.

The other problem is that, once you already have a hypothyroid condition, you’re going to have a hard time absorbing zinc, so the fact that you have a slow thyroid causes more of a zinc deficiency.

To make this simple, if you have any thyroid symptoms, don’t forget about zinc.

The Solution: How Do You Get Enough Zinc?

One way to get your zinc is to consume more shellfish. Alternatively, sea kelp and some nuts are also high in zinc. Finally, you can just take it as a supplement.

Overall, I believe that zinc is probably one of the most important trace minerals. It does so many things in addition to helping your thyroid - so whether you want to improve your subclinical hypothyroid or you simply want to optimize your health, it’s important to get enough.

If you would like more information, check out this video talking about this amazing trace mineral.

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Disclaimer: Our educational content is not meant or intended for medical advice or treatment.

Editor’s Note: This post has been updated for quality and relevancy.


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