Magnesium glycinate is generally the best choice for people with hyperthyroidism. It’s well absorbed, gentle on the stomach, and has calming properties that directly address two of hyperthyroidism’s most disruptive symptoms: anxiety and poor sleep. But the “best” form depends on which symptoms you’re dealing with, because hyperthyroidism depletes magnesium in specific ways that different forms can target.
Why Hyperthyroidism Drains Magnesium
Excess thyroid hormones force your kidneys to flush magnesium out faster than normal. A study on patients with Graves’ disease found that the degree of magnesium loss directly correlated with how elevated their thyroid hormone levels were. The more overactive the thyroid, the more magnesium the body wastes through urine.
This creates a frustrating cycle. Magnesium helps regulate heart rhythm, muscle relaxation, nerve signaling, and sleep, all of which hyperthyroidism already disrupts. Losing magnesium on top of that amplifies symptoms like heart palpitations, muscle cramps, tremors, insomnia, and anxiety. In the Graves’ disease study, when patients were treated with antithyroid medication, their fractional excretion of magnesium dropped significantly and serum magnesium rose from 0.72 to 0.84 mmol/l. That rebound confirms the thyroid was driving the loss.
Even if you’re on medication to control your thyroid levels, you may still run low on magnesium during the months it takes to reach stable hormone levels. Supplementing can help fill the gap while your body recovers.
Magnesium Glycinate for Anxiety and Sleep
Magnesium glycinate is magnesium bound to glycine, an amino acid that has its own calming effect on the nervous system. This combination makes it particularly useful for the anxiety, restlessness, and insomnia that come with hyperthyroidism. It’s also one of the most bioavailable forms, meaning your body absorbs a high percentage of what you take. Unlike some other forms, it rarely causes digestive issues like loose stools or cramping, which matters when hyperthyroidism is already speeding up your gut.
If anxiety, racing thoughts at night, or difficulty staying asleep are your primary complaints alongside hyperthyroidism, glycinate is the strongest match.
Magnesium Taurate for Heart Palpitations
Magnesium taurate pairs magnesium with taurine, an amino acid concentrated in heart muscle. Taurine supports healthy heart rhythm and blood pressure regulation. For people whose hyperthyroidism triggers noticeable palpitations, a rapid resting heart rate, or a pounding sensation in the chest, taurate addresses both the magnesium deficit and the cardiovascular stress at the same time. It’s also well absorbed and easy on the stomach.
Magnesium Citrate for General Repletion
Magnesium citrate is one of the most widely available and affordable forms. It has solid absorption and works well as a general-purpose supplement to restore depleted levels. The tradeoff is that citrate has a mild laxative effect, especially at higher doses. If you already deal with frequent bowel movements from hyperthyroidism (a common symptom), citrate may make that worse. It’s a reasonable option if your digestion is relatively stable and you want a straightforward way to boost your levels.
Forms to Avoid
Magnesium oxide is the most common form on store shelves, but it has the lowest absorption rate, often under 4%. You’d need to take much more to get the same benefit, and the unabsorbed magnesium sitting in your intestines acts as a laxative. For someone with hyperthyroidism already dealing with fast transit through the gut, this is a poor fit.
Magnesium sulfate (Epsom salts taken orally) and magnesium hydroxide (milk of magnesia) are similarly focused on the digestive tract rather than raising your blood and tissue levels. They’re useful for constipation, not for correcting a systemic deficiency.
How Much to Take
Most adults need 300 to 400 mg of elemental magnesium per day. “Elemental” is the key word here, because supplement labels can be confusing. A capsule might contain 500 mg of magnesium glycinate by weight, but only 100 mg of that is actual magnesium (the rest is the glycine molecule). Check the Supplement Facts panel for the amount listed as elemental magnesium or just “magnesium.”
Splitting your dose into two servings, one in the morning and one before bed, improves absorption and reduces the chance of stomach upset. Taking your evening dose about 30 to 60 minutes before sleep can amplify the calming effects, especially with the glycinate form.
One practical note: magnesium can interfere with the absorption of certain thyroid medications if taken at the same time. Separate them by at least four hours. If you take your thyroid medication in the morning, an afternoon and bedtime magnesium schedule works well.
Matching the Form to Your Symptoms
- Anxiety, insomnia, or muscle tension: Magnesium glycinate
- Heart palpitations or rapid heart rate: Magnesium taurate
- General repletion with stable digestion: Magnesium citrate
- Muscle cramps or spasms: Magnesium glycinate or magnesium malate
Some people combine forms, taking glycinate at night for sleep and taurate during the day for cardiac symptoms. This is safe as long as the total elemental magnesium stays within the recommended range. Going above 350 mg per day from supplements (the tolerable upper intake level set for supplemental magnesium) increases the risk of diarrhea, though many people tolerate more from well-absorbed forms like glycinate without issues.
Because the magnesium loss in hyperthyroidism is driven by the thyroid itself, your need for supplementation may decrease as your hormone levels normalize with treatment. The Graves’ disease research showed that once thyroid function improved, renal magnesium wasting dropped and serum levels recovered on their own. Supplementation bridges the gap during active disease and the early treatment period, when your body is still catching up.