The thyroid gland is responsible for the production of significant hormones that regulate the majority of metabolic functions like breaking down food into usable nutrients. Some people develop thyroid conditions that prevent proper production of the thyroid hormones. In this event, the synthetic hormone levothyroxine is used to replace the low producing hormone so your body can still function normally. As with any medication there are precautions and a high-fiber diet is one that may interfere in the proper absorption of levothyroxine.
Thyroid Gland and Levothyroxine
The pituitary gland at the base of your brain produces thyroid-stimulating hormone, or TSH, which travels in the bloodstream to your thyroid gland. The TSH communicates to the thyroid to produce the hormones tri-iodothyronine, or T3, and thyroxine, or T4. Damage to the thyroid or pituitary gland from varying causes like gland inflammation or autoimmune disease can hinder the production of T4 hormone resulting in an underactive thyroid condition including hypothyroidism, goiter or Hashimoto's disease. If physician testing reveals you have an underactive thyroid, he may recommend a prescription-strength thyroxine medication called levothyroxine.
Underactive thyroid, especially in the case of hypothyroidism, likely requires life-long treatment with levothyroxine. Proper use of this medication is imperative to maintain healthy thyroid function; your physician monitors this with annual lab testing to determine if the medication dose needs adjustment. Take levothyroxine on an empty stomach with a full glass of water so it properly absorbs in your body. If you consume certain foods, like fibrous grains or produce, or take supplements containing calcium or iron, at the same time as levothyroxine, absorption is impaired, nullifying its therapeutic effects on the thyroid. You should avoid supplements and high-fiber foods for several hours before and after you take levothyroxine.
Fiber is the indigestible portion of plant-based foods. It serves a variety of important functions including maintenance of digestive and bowel health, nourishing the good bacteria that reside in your colon and helping to keep your cholesterol levels low. The daily recommendation for fiber ranges from 25 to 35 g and should come from a variety of food sources. A food with 5 g or more of fiber per serving is designated as high-fiber. Whole grains like all bran or wheat products can contain 5 to 8 g of fiber per serving. Legumes, including lima, navy, black or pinto beans, have 5 to 7.5 g of fiber per serving. Fruit and vegetable varieties like pears, blackberries, potatoes and squash also have 5 to 7 g of fiber per serving.
Daily Fiber and Levothyroxine
When taking levothyroxine, you do not have to avoid fiber-filled foods in your daily diet, but you may have to adjust the time of day you consume them. In addition to fresh produce and grains, packaged foods may also contain fiber. Read nutrition labels to determine the amount of fiber per serving. Consult your physician for dietary recommendations and follow your prescription instructions for best results.