Frequently Asked Questions

Dietary fiber, also known as roughage, is the indigestible part of plant foods. Fiber has a host of health benefits, including reducing the risk of heart disease and type 2 diabetes.

Fiber is mostly in vegetables, fruits, whole grains, and legumes. There are two types of fiber — soluble and insoluble — and both play important roles in health:

Insoluble fiber does not dissolve in water and adds bulk to the stool, preventing constipation.

Soluble fiber absorbs water, forming a gel-like substance in the digestive system. Soluble fiber may help lower cholesterol levels and help regulate blood sugar levels.

Dietary fiber is an essential part of a healthful diet. It is crucial for keeping the gut healthy and reducing the risk of chronic health conditions.

Protection against heart disease

Several studies over the past several decades have examined dietary fiber’s effect on heart health, including preventing cardiovascular disease and reducing blood pressure.

People eating high fiber diets had significantly reduced risk of cardiovascular disease and lower mortality from these conditions.

The authors say that these heart protective effects could be because fiber reduces total cholesterol and low-density lipoprotein (LDL) cholesterol, also called ‘bad cholesterol,’ which is a major risk for heart conditions.

Better gut health

Fiber is important for keeping the gut healthy. Eating enough fiber can prevent or relieve constipation, helping waste to move smoothly through the body. It also encourages healthy gut microbiota.

Dietary fiber increases the bulk of stool, helps promote regular bowel movements, and reduces the time that waste spends inside the intestines.

Dietary fiber has a positive impact on gastrointestinal disorders, including:

• colorectal ulcer
• hiatal hernias
• gastroesophageal reflux disease
• diverticular disease
• hemorrhoids

Reduced diabetes risk

Adding more fiber to the diet may also have benefits for diabetes. Fiber can help slow down the body’s absorption of sugar, helping to prevent blood sugar spikes after meals. People who ate high fiber diets, especially cereal fiber, had a lower risk of developing type 2 diabetes. These individuals also reported a small reduction in blood glucose levels.

Weight management

For people aiming to lose weight, a diet high in dietary fiber can help regulate weight loss. High fiber foods help a person feel fuller for longer and may help people adhere to a diet.

Researchers concluded that people who increased their dietary fiber intake increased their weight loss and adherence to their dietary caloric restriction.

Types of dietary fiber

Fiber includes nonstarch polysaccharides, such as cellulose, dextrins, inulin, lignin, chitins, pectins, beta-glucans, waxes, and oligosaccharides.

Soluble and insoluble are the two types of dietary fiber.

Most high fiber containing foods have both insoluble and soluble fiber, so people do not need to think much about the difference. Instead, they can focus on overall fiber intake.

Soluble fiber

Soluble fiber dissolves in water and forms a gel-like substance in the stomach. Bacteria later break the gel down in the large intestine. Soluble fiber provides some calories to the individual.

Soluble fiber provides the following benefits:

• lowering LDL cholesterol in the blood by affecting how the body absorbs dietary fat and cholesterol
• slowing absorption of other carbohydratesthrough digestion, which can help regulate blood sugar levels

Good sources of soluble fiber include:

• beans
• fruits
• oats
• nuts
• vegetables

Insoluble fiber

Insoluble fiber does not dissolve in water and passes through the gastrointestinal tract, mostly intact. It does not provide calories.

Insoluble fiber helps build bulk in the stool, helping a person pass stool more quickly. It can also help prevent constipation.

Good sources of insoluble fiber include:

• fruits
• nuts
• vegetables
• whole grain foods

How much is too much?

Eating too much fiber can cause bloating, gas, and constipation. These side effects may occur if a person consumes more than 70 g of fiber a day. This is uncommon but may happen if someone is following a vegan, raw, or whole food diet.

Perhaps you have learned that you have a high chance of developing type 2 diabetes, the most common type of diabetes. You might be overweight or have a parent, brother, or sister with type 2 diabetes. Maybe you had gestational diabetes, which is diabetes that develops during pregnancy. These are just a few examples of factors that can raise your chances of developing type 2 diabetes.

Diabetes can cause serious health problems, such as heart disease, stroke, and eye and foot problems. Prediabetes also can cause health problems. The good news is that type 2 diabetes can be delayed or even prevented. The longer you have diabetes, the more likely you are to develop health problems, so delaying diabetes by even a few years will benefit your health. You can help prevent or delay type 2 diabetes by losing a modest amount of weight by following a reduced-calorie eating plan and being physically active most days of the week. Ask your doctor if you should take the diabetes drug metformin NIH external link to help prevent or delay type 2 diabetes.1

Research such as the Diabetes Prevention Program shows that you can do a lot to reduce your chances of developing type 2 diabetes. Here are some things you can change to lower your risk:

• Lose weight and keep it off.You may be able to prevent or delay diabetes by losing 5 to 7 percent of your starting weight.1 For instance, if you weigh 200 pounds, your goal would be to lose about 10 to 14 pounds.
• Move more.Get at least 30 minutes of physical activity 5 days a week. If you have not been active, talk with your health care professional about which activities are best. Start slowly to build up to your goal.
• Eat healthy foods most of the time.Eat smaller portions to reduce the amount of calories you eat each day and help you lose weight. Choosing foods with less fat is another way to reduce calories. Drink water instead of sweetened beverages.

Type 1 Diabetes

Type 1 diabetes is thought to be caused by an immune reaction (the body attacks itself by mistake). Risk factors for type 1 diabetes are not as clear as for prediabetes and type 2 diabetes. Known risk factors include:

Family history: Having a parent, brother, or sister with type 1 diabetes.

Age: You can get type 1 diabetes at any age, but it usually develops in children, teens, or young adults.

Currently, no one knows how to prevent type 1 diabetes.

Type 2 Diabetes

You’re at risk for type 2 diabetes if you:

• Have prediabetes.
• Are overweight.
• Are 45 years or older.
• Have a parent, brother, or sister with type 2 diabetes.
• Are physically active less than 3 times a week.
• Have ever had gestational diabetes (diabetes during pregnancy) or given birth to a baby who weighed over 9 pounds.
• Are an African American, Hispanic or Latino, American Indian, or Alaska Native person. Some Pacific Islanders and Asian American people are also at higher risk.
• If you have non-alcoholic fatty liver disease you may also be at risk for type 2 diabetes.

You can prevent or delay type 2 diabetes with proven lifestyle changes. These include losing weight if you’re overweight, eating a healthy diet, and getting regular physical activity.

Prediabetes

You’re at risk for prediabetes if you:

• Are overweight.
• Are 45 years or older.
• Have a parent, brother, or sister with type 2 diabetes.
• Are physically active less than 3 times a week.
• Have ever had gestational diabetes (diabetes during pregnancy) or given birth to a baby who weighed over 9 pounds.

Gestational Diabetes

You’re at risk for gestational diabetes (diabetes while pregnant) if you:

• Had gestational diabetes during a previous pregnancy.
• Have given birth to a baby who weighed over 9 pounds.
• Are overweight.
• Are more than 25 years old.
• Have a family history of type 2 diabetes.
• Have a hormone disorder called polycystic ovary syndrome (PCOS).

Gestational diabetes usually goes away after you give birth, but increases your risk for type 2 diabetes. Your baby is more likely to have obesity as a child or teen, and to develop type 2 diabetes later in life.

Before you get pregnant, you may be able to prevent gestational diabetes with lifestyle changes. These include losing weight if you’re overweight, eating a healthy diet, and getting regular physical activity.

Prediabetes means you have higher than normal blood sugar levels. Unmanaged prediabetes can lead to Type 2 diabetes. Prediabetes doesn’t always have symptoms, so it’s important to get blood sugar levels tested, especially if you’re at high risk. Losing weight, exercising regularly and eating healthy can reverse prediabetes and prevent Type 2 diabetes.

Your pancreas produces a hormone called insulin. Insulin allows blood sugar (glucose) into your cells so your body can use it as energy. In prediabetes, your cells don’t respond to insulin as they should.

In the prediabetes cycle:

• Cells become insulin resistant. They have a sluggish or low response to insulin.
• Your pancreas makes more insulin, trying to get the cells to respond.
• For a while, the extra insulin makes up for the weak response. Blood sugar levels stay normal.
• Eventually, your pancreas can’t keep up production. Extra glucose stays in your blood instead of entering your cells.
• Your blood sugar keeps rising. At this point, a blood test may show prediabetes.
• Without treatment, you can end up with Type 2 diabetes.

What are the symptoms of prediabetes?

Many people have no symptoms of prediabetes, often for years. Prediabetes may be invisible until it develops into Type 2 diabetes.

Some people with prediabetes may experience:

• Darkened skin in the armpit or back and sides of the neck, called acanthosis nigricans.
• Skin tags, small skin growths.
• Eye changes that can lead to diabetes-related retinopathy.

For people who have diabetes—or almost any other disease, for that matter—the benefits of exercise can’t be overstated. Exercise helps control weight, lower blood pressure, lower harmful LDL cholesterol and triglycerides, raise healthy HDL cholesterol, strengthen muscles and bones, reduce anxiety, and improve your general well-being. There are added benefits for people with diabetes: exercise lowers blood glucose levels and boosts your body’s sensitivity to insulin, countering insulin resistance.

Many studies underscore these and other benefits from exercise. Following are some highlights of those results:

Exercise lowered HbA1c values by 0.7 percentage point in people of different ethnic groups with diabetes who were taking different medications and following a variety of diets—and this improvement occurred even though they didn’t lose any weight.

All forms of exercise—aerobic, resistance, or doing both (combined training)—were equally good at lowering HbA1c values in people with diabetes.

Resistance training and aerobic exercise both helped to lower insulin resistance in previously sedentary older adults with abdominal obesity at risk for diabetes. Combining the two types of exercise proved more beneficial than doing either one alone.

People with diabetes who walked at least two hours a week were less likely to die of heart disease than their sedentary counter- parts, and those who exercised three to four hours a week cut their risk even more.

Women with diabetes who spent at least four hours a week doing moderate exercise (including walking) or vigorous exercise had a 40% lower risk of developing heart disease than those who didn’t exercise. These benefits persisted even after researchers adjusted for confounding factors, including BMI, smoking, and other heart disease risk factors.

In general, the best time to exercise is one to three hours after eating, when your blood sugar level is likely to be higher. If you use insulin, it’s important to test your blood sugar before exercising. If the level before exercise is below 100 mg/dL, eating a piece of fruit or having a small snack will boost it and help you avoid hypoglycemia. Testing again 30 minutes later will show whether your blood sugar level is stable. It’s also a good idea to check your blood sugar after any particularly grueling workout or activity. If you’re taking insulin, your risk of developing hypoglycemia may be highest six to 12 hours after exercising. Experts also caution against exercising if your blood sugar is too high (over 250), because exercise can sometimes raise blood sugar even higher.