Top Rated Thyroid Supplements

Supplements for slow thyroidThe thyroid is a butterfly-shaped gland at the front of the throat. It’s a small gland, weighing only 25 grams – but it’s powerful.

It produces two important hormones that control key functions in the body from metabolism and heart rate, to hair growth and reproduction: T3 and T4.

Thyroid Hormones Explained

The two main thyroid hormones are T3 and T4. “T” stands for thyroid and “3” or “4” indicate the number of iodine molecules attached to the hormone. T4 is produced first, and is then converted to the more active hormone, T3, by losing one of its iodine molecules. This conversion can occur in the thyroid gland, but more often in other areas of the body such as the liver, gut, muscles, and brain.

This production and conversion of thyroid hormones requires key nutrients, and can be inhibited or up-regulated by foods and herbs. The thyroid gland itself, and the tissues that are influenced by thyroid hormones, require a wide range of vitamins and minerals to function properly.

Thyroid Hormones in the Body:

  • Regulate metabolic rate
  • Control tolerance to temperature changes
  • Balance fat metabolism and burning vs. storing body fat
  • Regulate the nervous system, cognition and mental development
  • Influence carbohydrate and protein metabolism in the liver
  • Promote cardiovascular health and maintain the resting heart rate
  • Control bone turnover and calcium metabolism

A healthy thyroid ensures a healthy metabolism, balanced mood, quality sleep and fertility. With such a strong influence on the body, you really notice when something is wrong with your thyroid – but the symptoms can be vague…

The Two Common Thyroid  Irregularities

Hyperthyroid (Overactive Thyroid)

In certain conditions, the thyroid can go into hyper-drive. It can produce too much active thyroid hormone (T3), resulting in a fast metabolism, too much bone turn-over, cardiovascular damage, anxiety, . Symptoms include puffy eyes, irregular menstrual periods, difficulty gaining weight, frequent infections, excessive hunger, sweating, irritability, hair loss and anxiety. Sometimes hyperthyroid conditions can develop into hypothyroid conditions.

Hyperthyroid states can be caused by nutrient deficiencies, or autoimmune conditions including Graves disease.

Hypothyroid (Underactive thyroid)

An under-active thyroid struggles to produce and release enough active thyroid hormone (T3) to meet the body’s needs. Metabolism slows down, ca. Symptoms include unexplained weight gain, hair loss, depression, sensitivity to the cold, muscle aches, lethargy, brittle nails, constipation and sexual dysfunction.

Hypothyroid states can be caused by nutrient deficiencies (most commonly caused by iodine deficiency), or autoimmune conditions including Hashimoto’s thyroiditis, or as a long-term result of hyperthyroidism.

But there is good news!

Whether your thyroid is healthy, under-active, or over-active, there are nutrients and herbs that support the balanced production, secretion and activation of thyroid hormones. Here’s what to look for in an effective thyroid supplement:

Ideal Ingredients in Thyroid Supplements


Iodine is a key cofactor in the production of thyroid hormones, and to support the health of the thyroid gland itself. Iodine deficiency is a common cause of poor thyroid function, so it makes sense to include this essential nutrient in a thyroid supplement [7]. However, high amounts of supplemental iodine can throw the thyroid into a hyperthyroid state – which can then swing back to a more permanent low-function hypothyroid state. We recommend seeking the advice of a qualified nutritionist before taking a thyroid supplement that contains iodine. Good news – many supplement companies have used a safer alternative to pure iodine:

Seaweed Powder

Kelp, bladderwrack, or other seaweed powders or extracts naturally contain iodine – sea vegetables, including kelp, are some of the richest sources of iodine on the planet, and regular consumption of seaweeds can prevent the onset and development of certain thyroid conditions [1]. In this natural form, the body may be able to regulate how much iodine is absorbed to a degree… However, too much iodine is still harmful for the thyroid and should be used cautiously. Stick to low doses and speak to a qualified nutritionist or naturopath for personalised dosage advice if you suspect you have a thyroid condition.


Selenium is essential for the conversion of inactive thyroid hormones, T4 into active T3, and it also boosts iodine uptake into the thyroid [3]. As a powerful antioxidant, selenium also protects the thyroid against oxidative damage and immune attack. It can be a powerful therapy in people with autoimmune conditions that affect the thyroid, whether over-active or under-active [2].

Selenium is another supplement to be cautious of – high levels are toxic and even deadly. Stick to 200 – 400 mcg (that’s micrograms, not milligrams) per day and speak to a qualified nutritionist for personalized advice.


Tyrosine is the backbone of all thyroid hormones. It forms the backbone of the thyroglobulin, which is then converted into T4 and T3. While many people get enough tyrosine in their diet, supplementation may assist in boosting thyroid production in people with low thyroid function.

Tyrosine supplementation is generally not necessary in people with hyperthyroid conditions and could contribute to extra anxiety, high blood pressure, headaches and digestive issues.

Vitamin A

Vitamin A isn’t just for eye health – it has been shown that adequate levels of vitamin A are required for proper regulation of thyroid hormones [8]. It’s a two-way street – thyroid hormones are needed in the conversion of beta-carotene into vitamin A; and vitamin A is needed for the synthesis of thyroid hormones. As a key immune nutrient, vitamin A may also help to regulate any autoimmune attacks that are causing thyroiditis.

  • A 2012 study found that vitamin A supplementation significantly improved thyroid function in postmenopausal women diagnosed with hypothyroidism [8].


A little-known side-effect of an iron deficiency is reduced thyroid hormone production and utilization. Iron is used by the enzymes that move iodine into the thyroid gland to form thyroid hormones. It is also used throughout the body where it catalyzes the reaction between thyroid hormones and their target tissues.

Despite these key roles in thyroid health, iron is only occasionally used in thyroid supplements.

It is often left out for two reasons:

  1. iron binds to and inhibits the absorption of many other nutrients;
  2. an accumulation of iron is toxic

So, it’s best to err on the side of caution and only use supplements that contain iron when you have a confirmed diagnosis of low iron.

Ashwagandha (Withania somnifera)

As an adaptogenic herb, ashwagandha is able to adapt the thyroid – it could help to normalize both overactive and under-active thyroid function. Speak to a qualified herbalist before using this herb in hyperthyroid conditions though – most of the available evidence addressing under-active thyroid conditions.

  • A double-blind, randomized placebo-controlled trial in 2017 showed that 600mg of ashwagandha per day improved thyroid function in participants with subclinical hypothyroid function [4]

Schisandra Chinensis

Like ashwagandha, Schisandra is a powerful adaptogen that has been shown to improve mental and physiological performance when under any kind of stress [6]. It can help the immune system to down-regulate autoimmune attacks against the thyroid, and studies have shown that Schisandra contains lignans that protect cells against oxidative stress and may reduce the risk of thyroid cancer [5].

Nutrient Co-Factors

Herbs and nutrients never work in isolation. A supplemental supply of these co-factors can assist in boosting thyroid function:

  • Vitamin B12
  • Magnesium
  • Zinc
  • Copper
  • Manganese
  • Molybdenum

NOTE: Thyroid conditions MUST be treated by a qualified professional. Untreated or improperly treated autoimmune conditions can escalate unexpectedly, and cause damage to various organs. Seek treatment from a qualified professional.

Best 5 Thyroid Supplements

Here’s our round up of the five best thyroid supplements we could find to support healthy T3 levels:

#5 Pure Encapsulations Thyroid Support Complex (120 capsules)

Pure Thyroid SupportThis supplement has exceptional reviews, with anecdotal evidence suggesting it’s a great choice for hypothyroid conditions. Pure Encapsulations have included all of the major thyroid nutrients, including a therapeutic dose of 200mg of ashwagandha (standardized to contain 2.5% withanolides) per capsule – this is a great choice for under active thyroid conditions presenting with brain fog or afternoon energy crashes. Note that this formulation contains a higher dose of tyrosine than many other supplements – great for people feeling flat, but use with caution if you are prone to anxiety, high blood pressure, or panic attacks.

#4 Necessity Nutrition Natural Thyroid Support (66 capsules)

Natural Thyroid SupplementThis supplement ticks all the nutrient boxes – the only issue is some minerals are in poorly absorbed forms, and not very bioavailable. Some people will find that magnesium oxide, for example, triggers diarrhea! For those with less sensitive digestive systems, this is a great choice – it has everything from selenium to tyrosine, and herbs including schisandra and ashwagandha, as well as iodine in a safer form as kelp. Despite the questionable oxide minerals, this product has great reviews and could help to boost thyroid function.

#3 Gaia Herbs Thyroid Support Liquid Phyto-Capsules (120 capsules)

Gaia Thyroid SupportGaia Herbs have formulated a blend of thyroid-supporting herbal extracts including ashwagandha, Schisandra, and sea vegetables, along with a low dose of tyrosine. This is a great choice to boost thyroid function in combination with a healthy diet that supplies all of the key thyroid nutrients, plus it’s quite safe – this formulation reduces the risk of nutrient interactions or overloading with selenium or iodine. Keep in mind that ashwagandha is a powerful herb and can varied effects – speak to a qualified naturopath or herbalist if you have concerns.

#2 Zhou Thyroid Support (60 capsules)

Zhou ThyroidZhou have created a nutrient-dense blend for thyroid support, with a few key herbal extracts including schisandra and ashwagandha, and a range of key co-factors – great if you are under stress or experience anxious moods. They have also included a blend of warming cayenne pepper to promote circulation, and iodine-rich combination of bladderwrack and kelp sea vegetables. This great formula comes with rave reviews and a high star rating.

#1 RidgeCrest Herbals Thyroid Thrive (60 Capsules)

Thyroid Thrive by RidgecrestRidgeCrest Herbals get big props for this formulation – they tick every box when it comes to nutrients, herbs and cofactors needed to support thyroid function. This thyroid supplement has a great reputation and we can see why – with therapeutic doses of every nutrient needed for to support the thyroid (as well as other key glands including the adrenals), this is a holistic, synergistic formulation. The combination of bioavailable nutrients and proprietary herbal blend works well for most people.

View Thyroid Thrive on Amazon Here

Further Reading:

About James Lyons

James Lyons (BHSc Nutritional Medicine) is a clinical nutritionist, medical writer, and educator. He specialises in plant-based nutrition and is passionate about improving public access to reliable and accurate health information.

Speak Your Mind


This site uses Akismet to reduce spam. Learn how your comment data is processed.