The Best Vitamins for Thyroid Function, According to the Experts

If you live with a thyroid condition, particularly hypothyroidism, the most common thyroid disorder, chances are you’re dealing with a plethora of symptoms, including weight gain, fatigue, mood changes, and digestive issues. The thyroid gland is the butterfly-shaped gland that helps keep the brain, heart, muscles, and other organs working, so a problem with your thyroid can affect many different areas of your body.

Diet and lifestyle changes—including taking dietary supplements and vitamins for thyroid function—can be an important step in maintaining a healthy thyroid, but before you reach for a supplement, you need to better understand where your thyroid levels are and how they may be impacting your nutrient levels.

Measuring thyroid hormone and nutrient levels

At Parsley Health, doctors are trained in holistic medicine and conventional medicine to give you a wider scope of the problems you’re dealing with—and it starts with a thyroid test.

“In conventional medicine, when your primary care doctor screens for thyroid function, they often just look at one main lab value called your thyroid-stimulating hormone, otherwise known as your TSH,” explains Jamie Kyei-Frimpong, DNP, FNP-BC, a former nurse practitioner at Parsley Health New York. “But that doesn’t give the overall picture of your thyroid health,” says Dr. Jamie. Your doctor should also be assessing the conversion of other thyroid hormones and your nutrient levels of certain vitamins and minerals that impact that thyroid hormones and conversion.

Without looking at these key measures, it’s common to hear from your doctor that your thyroid hormone production is fine, even if you still feel kind of wonky, Dr. Jamie explains.

Dr. Jamie explains that you can have normal TSH levels but have poor conversion, which could lead to symptoms of thyroid diseases or hypothyroidism, aka an underactive thyroid. When you have hypothyroidism, the thyroid gland doesn’t make enough thyroid hormone to keep the body running normally, according to the American Thyroid Association. Understanding your own thyroid hormone conversion can help you determine the right thyroid vitamins and supplements for better thyroid health.

How thyroid hormone conversion works

The pituitary gland, found in your brain, signals to the thyroid how much hormone to produce. This thyroid hormone is what is known as T4, but your body needs to convert T4 into T3, which is the active form of the hormone, Dr. Jamie says. This active version of the hormone is needed in order for your body to be able to use it.

When the conversion from T4 to T3 is poor, or if you don’t have proper levels of vitamins and minerals that enhance or help that conversion process, your body can make enough T3. That’s where pesky symptoms come in.

How nutrient deficiencies affect thyroid hormone conversion

It’s common for people with hypothyroidism or an autoimmune disease that affects the thyroid to be deficient in certain vitamins and minerals that enhance the conversion process, says Dr. Jamie. You may not be getting the nutrients your thyroid needs from your diet alone, or you may have a gut-related issue that impacts the absorption of the vitamins and minerals from your food.

In both cases, supplements can help to fill nutritional gaps—even if you’re following a healthy diet filled with wholesome foods, like vegetables, fruits, lean protein, and healthy fats. Supplements contain easy to absorb versions of key vitamins and minerals so your body can access them quickly. Parsley Health’s Thyroid Balance supplement, for example, contains many of the nutrients that are important for thyroid health. This will help with the conversion of T4 into T3.

It’s worth noting that nutrient status isn’t the only thing that can lead to thyroid issues. Poor gut health or gut dysbiosis or liver function can impact your thyroid hormones, because portions of the hormone transcription process take place in the liver and the gut, explains Dr. Jamie.

That said, if your doctor determines your nutrient levels may be impacting your thyroid health, here’s a breakdown of some of the most important thyroid vitamins you’ll want to focus on.

Vitamin D

Vitamin D has been shown to improve thyroid TSH thyroid levels, explains Dr. Jamie. According to a November 2019 study in Medical Principles and Practices, which evaluated the vitamin B12 and vitamin D levels in 130 patients with hypothyroidism, vitamin D and B12 deficiencies are associated with hypothyroidism. Moreover, patients with hypothyroidism and a vitamin D deficiency showed significantly higher anti-TPO levels than those without a vitamin D deficiency.

Thyroid peroxidase (TPO) is an enzyme that aids in the production of thyroid hormones, according to the Mayo Clinic. If your doctor suspects you have a thyroid condition, they may order a TPO antibody test, and the presence of TPO antibodies in your blood could indicate that the cause of thyroid disease is an autoimmune disorder, such as Hashimoto’s or Graves’ disease. Parsley Health routinely runs this test.

Foods rich in vitamin D include salmon, trout, and eggs, but Dr. Jamie says the best way to get it is through the sun. “You really only need to be out in the sun for 10 to 20 minutes, but you need to go during the prime hours of 10 a.m. to 2 p.m.,” she says. Your doctor may also recommend Vitamin D supplements, including a Vitamin D3/K2 supplement.

Iodine

Iodine has also been shown to help improve TSH levels in those with hypothyroidism, Dr. Jamie says, however, it can be tricky to manage. “It’s needed to make T4, but we have to be careful about how much we’re supplementing because too much iodine can actually cause hypothyroidism,” she explains.

In fact, an October 2012 review in Current Opinion in Endocrinology, Diabetes and Obesity shows that overexposure to iodine can induce hypo- or hyperthyroidism in people with pre-existing thyroid conditions or those at high risk for them.

“We really just need 150 micrograms a day,” says Dr. Jamie. You can find iodine in kale, kelp flakes, and seafood, like shrimp, cod, and tuna. Some table salt is also supplemented with iodine. Before taking an iodine supplement, work with a doctor who can closely monitor your levels and ensure you’re not taking too much.

Vitamin A

“Vitamin A is also needed for T4 synthesis,” Dr. Jamie says. “It helps regulate T4 metabolism, but it can also inhibit TSH so that the TSH isn’t high.”

An August 2012 trial in the Journal of the American College of Nutrition suggests that vitamin A supplementation may help reduce the risk of hypothyroidism in premenopausal women. In the study, 84 women between the ages of 17 to 50 were put on a randomized, double-blind trial for four months. 56 of the women were obese and were randomly selected to take vitamin A or placebo. The other 28 women who weren’t obese received a vitamin A supplement. At the end of the trial, TSH levels were measured, and researchers found that the vitamin A supplement significantly reduced TSH concentrations in both obese and nonobese women while T3 concentrations increased.

While vitamin A supplementation can help with thyroid function, you can also find this important nutrient in a variety of delicious, healthy foods, like sweet potatoes, spinach, carrots, mangoes, and beef liver.

B Vitamins

“B vitamins have many interactions with thyroid function and hormone regulation, and we need B vitamins for detoxification and all of those processes,” Dr. Jamie says. If you are taking supplements for thyroid function with B vitamins, Dr. Jamie says it’s important to make sure that they are methylated so your body can utilize them more efficiently and support detoxification.

Iron

Along with selenium and zinc, iron is necessary for the version of T4 to T3, Dr. Jamie says. You can get ample amounts of iron from oysters, clams, liver, venison, and beef, but if you’re a vegetarian, you can also get it from spirulina and lentils. Just make sure you consume vitamin C with these plant-based iron sources to enhance their absorption.

Research in a May 2017 review in Thyroid found that people living with Hashimoto’s thyroiditis tend to be iron deficient because they may also have autoimmune gastritis, which impairs their ability to absorb iron.

Rhodiola

Rhodiola is an adaptogen that is commonly used to help treat mild or moderate depression, as well as stress. This is one compound that’s not naturally found in food, so you’ll need to take a supplement.

“You’ll find rhodiola in Parsley Health’s Thyroid Balance supplement to help combat stress because when your body is in times of chronic stress, you release higher amounts of the stress hormone, cortisol,” Dr. Jamie says. “When this happens, your body’s more focused on cortisol release, so it doesn’t put in the effort that it needs to convert T4 into T3.”

Instead, it directs it to something called reverse T3, another thyroid level that Dr. Jamie says is important to monitor. “We don’t want that to be high because it can result in hyperthyroid symptoms.”

Takeaway

If you have a thyroid condition or just want to make sure your thyroid health is in order, talk to your doctor and health coach before taking any thyroid supplements. They can help you find the right balance between dietary changes and supplements and vitamins for thyroid health all while monitoring your levels of key thyroid hormones and nutrients.