Berberine and thyroid: what does research show?

How does your thyroid work?

The thyroid is a small, butterfly-shaped gland at the front of your neck. It produces the thyroid hormones thyroxine (T4) and triiodothyronine (T3). T4 is mainly a storage form; in the body it is converted into the active T3.

Thyroid hormones act on almost every tissue. They help set the pace at which cells use energy and are involved in body temperature, heart rate, digestion and body weight, among other things.

Production is regulated from the brain. When more thyroid hormone is needed, the pituitary gland releases TSH: thyroid-stimulating hormone. That is why TSH, together with free T4, is the standard measure of thyroid function in a blood test. With autoimmune conditions of the thyroid, doctors also look at thyroid antibodies, such as TPO antibodies.

Read more about thyroid health and longevity

Does berberine affect the thyroid?

Berberine is mainly studied for its relationship with glucose and fat metabolism. Research specifically into berberine and the thyroid is much more limited, and most of it comes from animal and laboratory research.

What human research shows

There is one small clinical study in which thyroid hormone levels were followed. Eighteen people with Graves’ disease, a form of overactive thyroid, took part for six months. Eight of them used only the thyroid medicine methimazole; ten used methimazole together with berberine. Free T3 changed in both groups. TSH changed only in the group that also used berberine, as did the composition of the gut bacteria. With methimazole alone, the gut bacteria did not change.¹

The study is interesting, but small. Berberine was only studied alongside medication and under medical supervision. The study therefore says nothing about berberine on its own, or about people whose thyroid functions normally.

View the research

Thyroid antibodies and Hashimoto’s

Hashimoto’s thyroiditis is the most common cause of an underactive thyroid. As far as we know, no clinical studies with berberine have been published for this condition. Online stories about berberine and thyroid antibodies are therefore not based on human research.

Animal research

In a study in female rats with a disrupted thyroid, the researchers describe both stimulating and inhibiting changes in thyroid hormone values, depending on the dose.² That makes clear above all that the relationship is not straightforward, and that results from animal research cannot simply be translated to humans.

Are there thyroid side effects?

The side effects of berberine reported most often are gastrointestinal, such as nausea, a bloated feeling, diarrhoea or constipation.³ Berberine can also interact with medicines. Use during pregnancy and breastfeeding is not advised, and berberine is not suitable for babies.³

Because so little research has looked at the thyroid, it is not known how berberine relates to thyroid values over a longer period.

Thyroid, weight and berberine

Body weight is one of the things your thyroid helps regulate. When the thyroid works more slowly, energy use goes down and weight can increase. With an overactive thyroid, weight often goes down.

Berberine is also studied in relation to body weight, but that research looks at metabolism in general, not at the thyroid. Reviews do report changes, mainly at higher doses and over longer periods, but the quality of the studies varies and the evidence is not conclusive.³ Research into berberine and weight in people with a thyroid condition is lacking. If your weight changes because of your thyroid, that is a question for your doctor.

Read more about berberine and body weight

Can you take berberine with thyroid medication?

The most widely used thyroid medicine is levothyroxine, known under brand names such as Synthroid, Euthyrox and Thyrax. For an overactive thyroid, medicines such as methimazole (thiamazole) and carbimazole are used.

Research into berberine combined with levothyroxine is lacking. What is known is that berberine can affect enzymes that break down many medicines. In a randomised crossover study in healthy men, two weeks of 300 mg berberine three times a day changed the breakdown of test medicines via the enzymes CYP3A4, CYP2D6 and CYP2C9.⁴ Whether that is relevant for levothyroxine is not known.

View the research

Levothyroxine itself is sensitive to how you take it. It is usually taken on an empty stomach, 30 to 60 minutes before breakfast, and some supplements, such as calcium and iron, can affect how it works. That is why your doctor checks with regular blood tests whether your dose is right.⁵ This matters even more if you no longer have a thyroid, for example after surgery: you then depend entirely on your medication.

Does berberine interact with Synthroid or other thyroid medication? There is no direct evidence that it does, but no evidence that the combination is safe either. So:

• discuss berberine with your doctor or pharmacist before you start;
• ask whether your thyroid values should be checked again after you start;
• never stop or change your thyroid medication on your own.

What to look for in a berberine supplement

These points help you compare berberine supplements:

• Form. Ordinary berberine, often berberine HCl, is absorbed relatively poorly. Dihydroberberine is absorbed more easily and is then largely converted back into berberine in the body. In a small human crossover study, 100 and 200 mg dihydroberberine gave higher berberine levels in the blood than 500 mg ordinary berberine.⁶ That is why lower doses of dihydroberberine are studied.
• Dose. There is no official daily reference intake for berberine. Follow the recommended daily dosage of the product you choose; more does not automatically mean better.
• Quality. Look for a traceable origin, testing by an independent laboratory and a certificate of analysis per batch.
• Timing. Berberine is often taken with meals. This is in line with many clinical studies and may be more comfortable on the stomach.

Read more about dihydroberberine

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