Studies Show it is Better to Take Your Thyroid Medication at Bedtime
If you are taking thyroid hormone medication you’re doctor may have told you to not take them with vitamins. Some doctors may have recommended you separate them by an hour, 3 hours, and I’ve even heard a doctor suggest you need 12 hours inbetween. So, why the confusion, and what’s the conflict with taking nutritional supplements with thyroid medication?
Synthroid (levothyroxine, or synthetic thyroid hormone) is the most commonly prescribed thryoid medication. The concern with thyroid medication and nutritional supplements is that they compete for absorption in the gut. Calcium and iron are the main elements that compete for absorption and may reduce the effectiveness thyroid medication. However, not only can calcium and iron interfere with absorption, but so too can food, coffee, fiber, and certain medications, such as some antidepressants, Evista, and antacids.
If your nutritional supplement does not contain iron the issue is moot. However, most nutritional supplements provide calcium; and pregnant women, nursing mothers, and menopausal women absolutely need to take an additional 1000- 1500 mg of calcium (balanced with magnesium, of course). Supplements, particularly minerals, are better absorbed if taken with food or soon after eating. Thyroid hormone is better absorbed on an empty stomach.
One solution, though it may not be the best answer, is to take thyroid hormone in the morning on empty stomach at least an hour before eating, and then taking nutritional supplements and other medication an hour after eating. That would separate the medication from the supplements by at least two hours, which should be sufficient.
However, two studies, one published in the journal Clinical Endocrinology in 2007, and a larger randomized study published in the Archives of Internal Medicine in 2010 found that it may be better to take the thyroid medication, levothyroxine (Synthroid), at bedtime than in the morning on an empty stomach. Patients were found to have improved thyroid hormone profiles on blood work, because the thyroid hormone was found to be more effective (lower TSH levels, and higher free T4).
Taking thyroid hormone at night would work as long as it is separated by 2 to 3 hours from taking nutritional supplements, particularly those containing iron or more than 400 mg of calcium. Therefore, if you decide to take thyroid hormone at bedtime, take your evening nutritional supplements at dinner, and then at least 3 hours later (if not 4 hours) take the medication. (Melatonin does NOT interfere with thyroid hormone absorption, particularly if you use melatonin that is absorbed beneath your tongue, i.e., sublingual formulations.)
The benefits of taking your thyroid hormone at bedtime is that it appears to increase the absorption, and one does not have to wait to have breakfast or morning coffee.