How High-Fiber Foods Can Benefit Your Thyroid

Most of the foods you eat, including carbohydrates, fats, and proteins, are broken down and absorbed by your body. The exception is dietary fiber, sometimes called “roughage,” which passes through your body virtually untouched. When you have a thyroid condition, a diet that's high in fiber can be particularly beneficial to you by helping with weight loss and easing chronic constipation, a common effect of hypothyroidism (underactive thyroid), or diarrhea, a common outcome of hyperthyroidism (overactive thyroid).

Fiber's Benefits for Thyroid Patients

Fiber is an important part of anyone's diet, but there are many aspects of a high-fiber diet that are of particular importance and benefit to those with thyroid disease.

It Lowers Your Risk of Cardiovascular Concerns

Studies show that when you eat a high-fiber diet, you lower your risk of coronary artery disease and heart attack by as much as 40 percent to 50 percent. Research has also found that your risk of heart disease may be decreased by 9 percent for every 7 grams you increase your daily fiber intake.

Since thyroid disease puts you at a higher risk for heart disease, including coronary artery disease, stroke, and heart attack, this benefit is particularly meaningful.

In addition, soluble fiber in particular may help lower low-density lipoprotein (LDL), the "bad" cholesterol, which can also lead to less heart inflammation and reduced blood pressure levels. This benefit may also contribute to lowering your risk of heart disease.

It Helps With Weight Loss and Management

Weight gain, difficulty losing weight, and trouble maintaining a healthy weight can be a challenge when you have hypothyroidism. The more fiber you get in your daily diet, the lower your risk of obesity. This is likely because fiber makes you feel full, helping you eat less. Fewer calories each day can eventually lead to weight loss over time. 

It Aids Your Digestive System

Dietary fiber helps control the digestion of other foods, a helpful effect since digestion can be slow when you have hypothyroidism.

By eating a high-fiber diet, hard stools and constipation—common complaints of people with hypothyroidism—may also be resolved. This, in turn, may reduce the risk and severity of hemorrhoids, a common outcome of chronic constipation.

If you have hyperthyroidism, you may have issues with diarrhea, so upping your fiber intake can help regulate your bowel movements as well.

It Helps Control Blood Sugar Levels

People with diabetes on a high-fiber diet have a slower absorption of sugar, promoting better glucose levels. Eating a high-fiber diet may also decrease your chances of developing type 2 diabetes, a risk that's higher when you have thyroid disease.

It Reduces Your Risk for Diverticulitis

If you have hypothyroidism, you may be more likely to develop diverticulosis, an inflammation or infection of the small pouches lining your intestine. Insoluble fiber has been shown to reduce this risk. If you already have diverticulosis or inflammatory bowel disease, be aware that some people have worse symptoms with more fiber, while others have fewer symptoms.

Types of Fiber and Foods to Reach For

The Academy of Nutrition and Dietetics recommends that adult women consume 25 grams of total fiber per day and adult men consume 38 grams, with 10 to 15 grams coming from soluble fiber. As you age, you need less; once you're over the age of 50, women should get 21 grams and men should get 30 grams a day.

Having thyroid disease doesn't necessarily mean you need more fiber than any other individual. Ensuring that you get the recommended amount, however, may be especially important for you.

You can look up the amount of fiber and any other nutrient in many foods on the United States Department of Agriculture's (USDA) FoodData Central.

Soluble Fiber

Soluble fiber is easily dissolved in water where it forms a gel-like substance. This type of fiber has been shown to help lower blood cholesterol levels as well as blood glucose levels. You can find soluble fiber in these foods:

• Apples, with skin
• Barley
• Beans
• Carrots
• Citrus fruits
• Corn
• Hazelnuts
• Jicama
• Mixed vegetables (frozen)
• Oats
• Okra, cooked
• Onion (white, yellow, red; cooked)
• Parsnips
• Pears
• Prunes
• Peas, cooked
• Soy flour*
• Yams

Insoluble Fiber

Insoluble fiber makes your stool softer and easier to pass, helping to prevent constipation and keeping the pH level in your intestinal tract at an optimum level. The foods that are highest in insoluble fiber include:

• Almonds*
• Apple with skin
• Baking chocolate
• Barley, cooked
• Barley flour
• Bran cereal
• Blueberries
• Brazil nuts
• Broccoli*
• Brussels sprouts*
• Bulgur
• Cabbage*
• Carrots
• Cauliflower*
• Cereal party mix, homemade
• Cherries
• Chestnuts
• Coconut
• Corn nuts
• Corn
• Cranberries
• Elderberries
• Figs
• Flaxseed
• Gooseberries
• Green beans
• Guava
• Hickory nuts
• Hominy
• Jicama
• Kale*
• Kidney beans
• Kiwi
• Kumquat
• Lentils
• Macadamia nuts
• Mandarin oranges
• Mango
• Millet*
• Mushrooms
• Nectarine
• Oatmeal
• Oyster
• Papaya
• Pasta, cooked
• Peanuts*
• Pears
• Peas
• Pine nuts
• Pineapple
• Pistachios
• Potatoes
• Prunes
• Pumpkin seeds
• Pumpkin puree
• Quinoa
• Raisins
• Raspberries
• Rhubarb
• Rice (brown, cooked)
• Rutabaga
• Rye flour
• Sauerkraut
• Sorghum
• Spinach
• Split peas
• Sprouts
• Squash
• Strawberries
• Sunflower seeds
• Sweet potato
• Tomato paste
• Tomatoes
• Trail mix
• Turnips
• Vegetable juice
• Walnuts
• Wheat bran germ
• Whole wheat flour
• Wild rice (cooked)

*Note that these high-fiber foods are also high in goitrogens, which can affect your thyroid (see more below).

Starting a High-Fiber Diet

After considering all the benefits of a high-fiber diet, you may be eager to get started. There are some important considerations to keep in mind before you begin.

• Start slow. Don't jump from 10 grams to 30 grams of fiber in one day. You need to give your digestive system time to adjust because adding too much fiber too quickly can cause discomfort.
• Be aware of grain sensitivities. Try to incorporate as many fiber-rich foods as you can into your daily menu, but know that, like many thyroid patients, you may be sensitive to grains—in particular, wheat. If grains seem to be an issue for you, ask your healthcare provider to test you for celiac disease; your risk of having it is higher when you have autoimmune thyroid disease (Hashimoto's thyroiditis or Graves' disease). You may instead have a gluten or other grain sensitivity that would benefit from eliminating an offending grain from your diet.
• Focus on high-fiber foods beyond grains. Though high-fiber grains, bread, and pasta give you fiber, they can also derail your weight loss efforts if you eat too much. When you use fiber to help with weight loss, it's best to concentrate on the highest-fiber vegetables, legumes, beans, nuts, seeds, and to a lesser extent, fruits.
• Drink more water. It's a good idea to increase your intake of water as well to help avoid bloating, cramping, pain, and gas.
• Don't overdo it. Along with increasing your intake too fast, getting too much fiber can also cause the above-mentioned symptoms, so be sure not to go overboard in your efforts to up your fiber intake. Aim for the daily recommended amount.
• Consider fiber supplements. You have to eat a great deal of food in order to get to targeted fiber levels. To get to the optimal intake of fiber a day, you may need to add a fiber supplement in addition to emphasizing fiber-rich foods in your diet, though it's best to get your fiber from food if you can.

Fiber Supplements

There are a number of different fiber supplements available over-the-counter. Two of the most popular types include:

• Psyllium: Studies have found that taking psyllium before you eat may help you eat less and feel full more quickly during a meal, as well as keep you feeling satisfied for a longer period of time afterward. Psyllium husk is found in commercial products like Metamucil. It's inexpensive and, when taken in capsule form, it's portable and easy to take.
• Guar gum: A high-fiber supplement that's found in a popular fiber powder product called Benefiber, guar gum dissolves completely into drinks like juice, water, or smoothies without adding grit, bulk, or taste (the same cannot be said for other fibers, including psyllium).

Fiber supplements can cause gas, cramping, bloating, or diarrhea in some people, especially when you first start taking them. As with high-fiber foods, increase your dose slowly and drink plenty of water.

Supplements can also interfere with the absorption of certain medications, so talk to your healthcare provider or pharmacist before you start taking one.

Cautions

As someone with thyroid disease, if you switch from a low-fiber to a high-fiber diet, there are two things you should be careful about in your diet:

• Medication interaction: Be sure that you're taking your thyroid medicine at least an hour before eating or taking any fiber supplement. Fiber can affect medication absorption and significantly change your thyroid drug dosage requirements. Have your thyroid function tested six to eight weeks after starting a high-fiber diet to make sure you don't need a dosage change.

A Word From Verywell

Altogether, fiber is more than it appears. It works with, and within, your body to maintain gut health. As research continues to associate gut health with immune function, improving your digestive health by increasing your fiber intake may provide some protection from autoimmune disorders. Talk to your healthcare provider about any concerns or questions you have about adding more fiber to your diet, how it may affect your thyroid medication, and how often you'll need to come in for follow-ups.