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Updated December 20, 2014.

For people with thyroid disease -- whether hypothyroid (underactive thyroid) or hyperthyroid (overactive thyroid), Hashimoto's disease or Graves' disease, or other conditions, there are some important things to know about foods and drinks, and their interaction with your health and medications. Here are ten things to know about thyroid conditions and your diet, food and beverages.

1. About Goitrogenic Foods

Goitrogens are substances -- occurring naturally in certain foods -- that can cause the thyroid gland to enlarge, which is called a goiter.

Goitrogenic foods can also function like an antithyroid drug and actually slow down the thyroid and make it underactive (hypothyroidism.)
The main goitrogenic foods are cruciferous vegetables like broccoli, cauliflower, kale, and cabbage, among others, as well as soy foods. Here is a more detailed list of common goitrogens.

If you still have a functional (or semi-functional thyroid gland), and are hypothyroid, you should be careful not to overconsume raw goitrogenic foods. If you are hyperthyroid, you may want to talk to a nutritional practitioner about incorporating more goitrogenic foods into your diet.
If you are hypothyroid, you don't need to avoid goitrogenic foods entirely. The enzymes involved in the formation of goitrogenic materials in plants can be at least partially destroyed by heat, allowing you to enjoy these foods in moderation if they are steamed or cooked.
If you are hypothyroid, you don't need to avoid goitrogenic foods entirely. The enzymes involved in the formation of goitrogenic materials in plants can be at least partially destroyed by heat, allowing you to enjoy these foods in moderation if they are steamed or cooked.

2. Coconut Oil

You may hear coconut oil recommended for thyroid patients, and while it can be a healthful option, it's not a cure-all or treatment for thyroid disease. It's just a thyroid-friendly option to replace other fats and oils in your diet.
 

3. Soy May Be a Problem

Soy both acts as a goitrogen, and inhibits thyroid hormone absorption. Don't overconsume soy, especially processed and high-phytoestrogen forms of soy, like shakes, powders, soy milk, bars, and supplements. You may want to eliminate soy, or limit soy consumption to fermented forms, like tempeh, in small quantities as a condiment, and not as a primary protein replacement.
If you are hyperthyroid, you may want to talk to a nutritional practitioner about incorporating more soy into your diet.

4. Coffee And Thyroid Medication

You should not take coffee until an hour after you've taken your thyroid hormone replacement medication. Otherwise, the coffee can affect absorption, and make your thyroid medication less effective.
(Note: if you absolutely must have both your thyroid medication and coffee at the same time, talk to your physician about the liquid, capsule form of levothyroxine, which is apparently not affected by coffee.)

5. Calcium-Fortified Orange Juice And Your Thyroid Medication

You should not take calcium-fortified orange juice with your thyroid medication. Wait at least three to four hours after taking your thyroid medication before taking calcium-fortified juice, calcium supplements, or iron supplements, as they can interfere with your absorption of thyroid medication.

6. Iodized Salt

In some areas of the world, iodized salt is an essential way to prevent iodine deficiency, cretinism and retardation due to iodine deficiency in pregnant women. In the U.S., however, many people have limited their salt intake, or stopped using iodized salt.
Keep in mind that about one-fourth of the U.S. population is now somewhat deficient in iodine, and that percentage appears to be on the rise again, after years of stable iodine levels (due to iodized salt intake.) You need enough iodine -- but not too much -- for the thyroid to function properly.

7. Celiac, Gluten and Wheat

A subset of autoimmune thyroid patients have dietary-triggered autoimmunity, due to celiac disease, or a wheat/gluten intolerance. For these patients, going on a gluten-free diet may eliminate antibodies, and cause a remission of their autoimmune thyroid disease. Even for some patients who do not have celiac disease, going on a gluten-free diet may reduce antibodies, reduce bloating, and help with energy and weight loss.

8. High-Fiber Foods

Many thyroid patients struggle with constipation, and extra weight. One of the key tactics that can help is increasing fiber intake, particularly from foods. Here is a list of high-fiber foods for thyroid patients.
Keep in mind, however, that if you switch to a high-fiber diet, you should get your thyroid rechecked in eight to twelve weeks to see if you need a dosage readjustment, as fiber can affect absorption of medication.

9. Mini-Meals

Many people hear that to raise metabolism, you should eat "mini-meals" -- or "graze" all day on smaller meals. But this may be exactly the wrong thing to do for thyroid patients who are trying to lose weight. The reason why fewer meals, spaced further apart may be more effective for thyroid patients than mini-meals and grazing is in helping to manage the leptin and insulin levels.

10. Water

One of the most powerful things thyroid patients can do to help their health and metabolism is to drink enough water. Water helps your metabolism function more efficiently, and can help reduce your appetite, get rid of water retention and bloating, improve your digestion and elimination, and combat constipation. Some experts even say that we should drink one ounce of water per pound of scale weight.