If you've been diagnosed with an underactive thyroid, or hypothyroidism, you may have heard that what you eat could affect your condition, or that certain foods or supplements may interact with your medications. While there's no specific "thyroid diet," there are a few things that people with hypothyroidism should know.

Spacing out thyroid medication and foods

Unlike some medications that should be taken with meals, thyroid hormone pills should not be taken with food or supplements.

If possible, take the medication on an empty stomach, or an hour before eating. If you eat foods that are rich in iron, such as fiber or calcium, meats, lentils or broccoli, it's best to wait at least two hours after you have taken the medication.

If you take calcium or iron supplements, make sure to wait several hours before taking the medication. The American Thyroid Association (ATA) calls a 4-hour separation between medication and supplements "traditional, but untested." Make sure to speak with your health care provider (HCP) before taking any dietary supplements.

What about thyroid pills and other meds?

You should also let several hours pass between taking thyroid pills and some ulcer medications, such as sucralfate (Carafate, ProThelial and Orafate) or certain cholesterol-lowering drugs, including cholestyramine (Prevalite and Questran) and colestipol (Colestid).

It's important to discuss all possible medication interactions with your HCP. Certain antibiotics, for example, could increase or decrease absorption of your thyroid medicine.

Eating right for your thyroid

There's no evidence that any particular diet will improve thyroid function in people with hypothyroidism. That said, it's still important to be mindful of what you eat. Be sure to follow a healthy diet that emphasizes fiber and nutrient-rich fruits and vegetables, nuts and complex carbohydrates, as well as lean protein. Choose foods with unsaturated fats, such as olive oil, fatty fish and seeds. Meanwhile, limit your intake of processed products and foods high in salt, sugar and unhealthy saturated fats.

Cauliflower and soy aren't the enemy

Eating large amounts of soy could reduce thyroid hormone production because it has antithyroid effects. (An iodine deficiency worsens these effects while iodine supplementation helps offset them.) But it's important to understand that people who don't have an iodine deficiency won't develop hypothyroidism from eating soy. This issue, however, is uncommon since iodine has been added to soy-based formulas since the 1960s.

You may also think you should steer clear of biotin, a substance found in some supplements as well as in some hair and nail products. Biotin actually does not alter thyroid hormone levels, but it can make measurements inaccurate. So, it's a good policy to stop taking it at least one week before your thyroid blood test if you are taking more than 5,000 micrograms (mcg) of biotin daily.

It's commonly believed that cruciferous vegetables are bad for your thyroid as well. For most people being treated appropriately for hypothyroidism, however, there is no need to avoid eating these foods, which include cabbage, cauliflower, broccoli, Brussels sprouts, bok choy and kale. In animals fed very high amounts of cruciferous vegetables, hypothyroidism can develop. But in studies involving people, a similar effect was detected only in those with an iodine deficiency.

So, what about iodine?

It's true: Having an iodine deficiency can devastate thyroid function. This may tempt you to be proactive about your health and try a supplement but, odds are, you're getting all the iodine you need through your diet alone. In the United States, iodine deficiency hasn't been a major cause of hypothyroidism for many years, thanks to initiatives from the 1920s that added iodine to salt. But keep in mind, sea salt contains only a small amount of iodine. If you prefer to use sea salt in your cooking, you don't have to give it up entirely, but you may want to include some regular iodized table salt in your diet as well.

Although excessive intake of iodine from supplements could alter your thyroid hormone level, iodine-rich foods, such as milk, most seafood, eggs and soy products are reasonable to consume.

Possible exceptions to this rule are expectant and nursing mothers. These women may benefit from taking a daily iodine supplement or a prenatal vitamin that contains iodine since the recommended dietary allowance for the mineral increases during pregnancy. If you're pregnant or breastfeeding, talk to your doctor to determine if a supplement is safe and appropriate for you.

Be cautious about selenium

Selenium is necessary for a healthy thyroid but skip the supplement unless it's recommended by your doctor. Taking too much of this essential element could make you sick. The recommended daily value for those age 14 and older is 55mcg (pregnant and nursing women need slightly more). In the U.S. however, the average adult is getting about twice as much as they need, making selenium deficiency rare.

And remember: Selenium-rich foods are all around us "” tuna, tofu, pork chops and nuts. In fact, just one chopped-up Brazil nut sprinkled onto your smoothie or oatmeal will give you roughly 90mcg, or more than a day's worth.

This article originally appeared on Sharecare.com.