Dietary fiber is an important part of digestive health. An average of 25 to 30 g of fiber per day maintains bowel regularity and intestinal functions. However, if you have a slow thyroid, or hypothyroidism, prescription medications you may take like levothyroxine can be hindered by too much fiber in your diet. Do not eliminate fiber from your diet, but consult your physician for fiber recommendations if you are taking thyroid medication. Whole grains, fruits, vegetables, nuts and beans are all rich sources of fiber that you may need to limit.
Hypothyroidism and Levothyroxine
The thyroid is a small gland inside your neck located below your voice box. It is responsible for producing two hormones, T3 and T4, which regulate metabolic functions like the breakdown of food and its use as energy. Damage to the thyroid gland from autoimmune disease, inflammation or pituitary gland disruptions can cause your thyroid to produce too little T4 hormone. The result is hypothyroidism with symptoms of a slowed metabolism, fatigue, weight gain, digestive upset and body temperature irregularities. Levothyroxine, a synthetic thyroid hormone medication, replaces the hormone your thyroid gland no longer makes properly. It is a lifelong treatment prescribed by your physician for hypothyroidism, but foods high in fiber taken with this medication inhibit proper absorption.
High-fiber whole grain breads, like dark rye bread, whole wheat bread, high-bran bread or seven grain bread, have 5.8 to 7.0 g of fiber per 2-slice serving. A 1-cup serving of all-bran cereals and oatmeal have 2 to 10 g of fiber. Brown rice has a higher fiber content than white rice at 5.5 g per 1/2 cup serving and wheat tortillas average 2 g of fiber per 6-inch shell.
High-Fiber Fruits and Vegetables
One large orange, a medium peach with skin, a medium apple with skin and 1/2 cup of fresh strawberries each yields 2 to 3.1 g of fiber per serving. A 1/2 cup serving of raspberries, one slice of watermelon or 1/2 cup of prunes has 2.8 to 4.5 g of fiber. Yams, sweet potatoes and white potatoes have 2.2 to 6.8 g of fiber with yams and sweet potatoes yielding the most fiber content. A 1/2 cup serving of cooked spinach yields 7.0 g of fiber, while broccoli and Brussels sprouts are also high-fiber foods with 3.0 to 7.0 g per 1/2 cup serving, depending on preparation.
Nuts and Beans
A 1/4 cup serving of walnuts, almonds, peanuts and chestnuts each yields 1.1 to 2.4 g of fiber. MayoClinic.com notes you should especially avoid taking walnuts and soy products with thyroid medication. Legumes are especially high in fiber; a 1/2 cup serving of kidney, pinto, black, lentils and certain pea varieties each contains up to 18 g of fiber.