What Vitamins, Foods, and Drinks Should You Avoid with Hypothyroidism?

Vitamins and supplements that may affect thyroid function or interfere with medication absorption

If you’re being treated for hypothyroidism, use caution when it comes to the following supplements, as they can interfere with the absorption of your thyroid medication:

• calcium
• iron
• iodine

Calcium and iron supplements

Proper absorption of your thyroid medication (levothyroxine) is needed in order for it to work effectively. When it isn’t absorbed well, it is less effective at restoring your thyroid hormone levels.

If you need to take iron or calcium supplements, talk with your doctor about the best time to do so. It’s generally recommended to take iron supplements at least 4 hours before or after taking levothyroxine.

Alternatively, you can ask your doctor about switching to liquid levothyroxine. It’s primarily absorbed in the small intestine, and this may help decrease the risk of absorption problems caused by these interactions.

Iodine supplements

While iodine is important for making thyroid hormones, most people in the United States already get enough through iodized salt and common foods.

Taking too much iodine, especially without a proven deficiency, can make thyroid problems worse, especially in people with autoimmune conditions like Hashimoto’s thyroiditis.

For example, research shows that too much iodine is toxic to thyroid cells. In people who are more prone to thyroid disease, this may trigger or worsen inflammation that may lead to Hashimoto’s thyroiditis, a type of hypothyroidism caused by an autoimmune reaction.

Due to this, talk with a healthcare professional before taking iodine supplements if you’ve been diagnosed with Hashimoto’s thyroiditis.

Foods and beverages that may affect thyroid function or interfere with medication absorption

Similar to iron and calcium supplements, some evidence suggests that certain foods and beverages may interfere with the absorption of levothyroxine.

These include:

• high-fiber foods
• soy products
• milk
• coffee
• certain fruit juices, such as grapefruit juice and orange juice
• papaya

It’s important to point out that the evidence for some of these is rather limited or conflicting. For example, some studies have found that soy has little clinical impact on levothyroxine absorption, and avoiding it has few proven benefits.

Nevertheless, if you’d like to prevent interactions with these foods, you can do so by putting enough space between when you take your levothyroxine and when you eat.

Doctors typically recommend taking your medication on an empty stomach with water, 30 to 60 minutes before eating, or at bedtime, at least two hours after the last meal. This gives your medication ample opportunity to absorb properly.

Goitrogens

A goitrogen is a substance found in certain foods, such as cruciferous vegetables like kale, broccoli, and cabbage. When eaten in moderate amounts, these vegetables are nutritious additions to your diet, especially if cooked.

However, if consumed in excess, goitrogens can interfere with thyroid function by:

• Blocking iodine: Goitrogens may prevent iodine from entering the thyroid gland, which is needed to produce thyroid hormones.
• Interfering with TPO: The thyroid peroxidase (TPO) enzyme attaches iodine to the amino acid tyrosine, which together form the basis of thyroid hormones.
• Reducing TSH: Goitrogens may interfere with thyroid stimulating hormone (TSH), which helps the thyroid gland produce hormones.

Getting enough iodine and selenium in your diet can also help limit the effects of goitrogens on your thyroid function.

In addition, some research has cast doubt on the idea that goitrogen-containing vegetables have a negative effect on the thyroid gland.

Talk with your doctor if you have concerns about your diet and how it may affect your thyroid function.

Foods high in iodine

Similar to the iodine supplements, it’s a good rule of thumb to be mindful when consuming foods that are high in iodine, as too much iodine can make thyroid problems worse, especially if you have Hashimoto’s thyroiditis.

However, it’s worth noting that these foods should not be avoided unless a doctor gives specific instructions. They are part of a healthy diet and are not harmful for most people with hypothyroidism.

Examples of foods that are naturally rich in iodine include:

• seaweed
• seafood like cod, oysters, and shrimp
• dairy products like milk and yogurt
• eggs

It’s also important to point out that some foods, such as breads and pastas, are iodine-enriched. Many table salts are also iodized. As such, be sure to check food labels while shopping.

How to reduce interactions with your thyroid medication

A 2015 survey of 925 people taking levothyroxine found that high percentages of respondents reported consuming medications, supplements, or foods that could interfere with levothyroxine.

Just over 13% of respondents to the survey also reported difficulty managing their hypothyroidism. This underlines the importance of taking steps to reduce interactions with your thyroid medication.

When to take your thyroid medication

Your doctor will typically suggest taking levothyroxine in the morning before breakfast

To maximize absorption and prevent interactions, it’s recommended to take levothyroxine:

• on an empty stomach, 30 to 60 minutes before eating breakfast
• four hours before or after taking medications or supplements that can affect absorption

Other medications that can affect levothyroxine absorption

Some examples of medications and supplements that can affect levothyroxine absorption include:

• antacids
• proton pump inhibitors
• bile acid sequestrants, a type of cholesterol-lowering medication
• sodium polystyrene sulfonate, a potassium-binding medication
• sevelamer, a phosphate-lowering medication
• orlistat, a weight loss drug
• iron and calcium supplements

If you ever have any questions or concerns about how to take levothyroxine, it’s always a good rule of thumb to ask your doctor for advice.

Takeaway

If you’re being treated for hypothyroidism, there are certain supplements, foods, and beverages that you may want to limit or avoid. Some may interfere with your thyroid medication, while others may affect your thyroid function.

For example, iron and calcium supplements, high fiber foods, and soy products may interfere with your body’s absorption of levothyroxine. Meanwhile, consuming excess iodine or foods containing goitrogens could affect your thyroid function.

If you have concerns about thyroid disease, diet, and supplements, have a conversation with your doctor. They can give you dietary recommendations to help boost your thyroid health while avoiding medication interactions.