What Are Complex Carbohydrates?

Medically Reviewed By Adrienne Seitz, MS, RD, LDN

Complex carbohydrates comprise three or more sugar molecules. Simple carbohydrates have one or two sugar molecules. There are two primary types of complex carbohydrates: starch and fiber. This article will discuss complex carbohydrates, including how they are different from simple carbohydrates. It will also provide a list of foods with complex carbohydrates and some of the health benefits they provide.

What are complex carbohydrates?

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Felix Chacon/Stocksy United

Complex carbohydrates are longer connections of sugar molecules that usually comprise three or more monosaccharide units. Monosaccharides are the simplest form of sugar, and there are three types: glucose, fructose, and galactose.

What is the difference between simple carbohydrates and complex carbohydrates?

The chemical structure of a food or beverage indicates whether it is a simple or complex carbohydrate.

What are simple carbohydrates?

Simple carbohydrates are shorter chains of glucose that the body can break down very easily.

Food sources of simple carbohydrates include any type of sugar — including white, brown, powdered, or cane — and products such as honey, maple syrup, molasses, candy, pastries, and sugar-sweetened drinks. Natural fruits and fruit juices also have simple carbohydrates.

Simple vs. complex carbohydrates

The body converts both simple and complex carbohydrates into glucose, which it stores in the liver and muscles as glycogen. Additionally, the body can store the excess glucose from either type of carbohydrate as fat.

However, simple and complex carbohydrates produce different responses Trusted Source American Heart Association Highly respected national organization Go to source in the body and have different health benefits.

Simple carbohydratesComplex carbohydrates
shorter chains of one or two of sugar moleculeslonger chains of three or more sugar molecules
take a shorter time to digest and absorbtake a longer time to digest
immediate but short lasting source of energylonger lasting source of energy
faster spike in blood sugar and insulin releaseslower increase in blood sugar
energy crash that can cause hunger, irritability, or anxietymore stable energy and mood
can increase triglycerides, a risk factor for heart disease and diabetescan help reduce cholesterol and prevent or manage diabetes

The crash you may experience after consuming simple carbohydrates is postprandial or reactive hypoglycemia. It may be a symptom Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source of prediabetes or diabetes.

What are types of complex carbohydrates?

Complex carbohydrates fall into classifications defined broadly as starch, fiber, or glycogen.

Starch

The small intestine breaks down starch. It becomes glucose, the primary source of fuel for our cells.

Starch is made up of two types of polysaccharides: amylose and amylopectin.

Fiber

Microflora in the large intestine metabolize fiber. Fiber serves as a fuel, called a prebiotic, to feed the beneficial bacteria in our gut. Research shows that these prebiotics influence our physiology in many ways and play a significant role in health.

You can find fiber in plants, including fresh fruits and vegetables. The two primary types of dietary fiber are soluble and insoluble.

Soluble fiber breaks down in water in your stomach and helps slow digestion. It helps manage your glucose and cholesterol levels, which reduces your risk of conditions like diabetes.

Insoluble fiber does not break down in your stomach. As it moves through your digestive system, it improves bowel function and health. It can help reduce constipation and improve regularity.

Glycogen

Your liver and muscles store glycogen in the form of glucose. This type does not refer to carbohydrates consumed through food.

What are examples of foods with complex carbohydrates?

Foods often contain both simple and complex carbohydrates. The foods listed below are good sources Trusted Source Dietary Guidelines for Americans (USDA) Governmental authority Go to source of complex carbohydrates and can provide several health benefits Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , including improved digestion and blood sugar management.

Foods that contain soluble fiber

  • apples
  • oats
  • barley
  • bananas
  • lima beans
  • broccoli
  • black beans
  • Brussels sprouts
  • root vegetables
  • beans and legumes such as:
    • lentils
    • black beans
    • kidney beans
    • garbanzo beans
    • pinto beans
    • red beans
    • soybeans

Foods that contain insoluble fiber

  • bran
  • seeds
  • nuts
  • quinoa
  • wheat flour
  • zucchini
  • celery
  • cauliflower
  • green beans
  • many fruit and vegetable skins, including potato, grapes, apples, and broccoli stems
  • whole grains such as:
    • rye
    • barley
    • quinoa
    • amaranth
    • oats
    • buckwheat
    • millet
  • nonstarchy vegetables such as:
    • broccoli
    • leafy greens, including kale, spinach, arugula, romaine, collards
    • cabbage
    • bell peppers
    • cauliflower
    • asparagus
    • zucchini
    • celery
    • radishes
    • eggplant
  • chia seeds
  • flaxseed

Starchy vegetables

  • butternut squash
  • pumpkin
  • peas
  • potatoes
  • corn
  • acorn squash

What are the health benefits of complex carbohydrates?

Because they take longer to digest, complex carbohydrates generally provide a more sustainable source of energy relative to simple carbohydrates.

Many sources of complex carbohydrates have a high nutritional value and contain fiber, which has numerous health benefits.

Although the research demonstrating the many health benefits of fiber continues to evolve, some known health benefits of fiber include Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source :

  • improved regularity of bowel movements
  • reduced constipation
  • softer stools that are easier to pass
  • lower cholesterol
  • more stable blood sugar
  • decreased risk of colorectal cancer
  • improved appetite regulation and weight loss

Talk with your doctor about how to increase your intake of healthy complex carbohydrates and how they can help reduce your individual risk of certain conditions.

Other frequently asked questions

These are some other questions people often ask about complex carbohydrates. Adrienne Seitz, MS, RD, LDN, reviewed the answers.

Is fiber a complex carbohydrate?

Yes, fiber is a primary type of complex carbohydrate, along with starch.

Do bananas have complex carbohydrates?

Bananas contain a combination of complex carbohydrates and simple carbohydrates. The composition of each depends on several factors, including ripeness Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source .

What is the healthiest carbohydrate?

Your individual medical history and health goals can help determine the right balance of carbohydrates in your diet. Generally speaking, complex carbohydrates that are high in fiber and nutrient dense tend to be healthier options than sugary foods high in simple carbohydrates.

Your doctor can refer you to a registered dietitian who can evaluate your goals and help you develop meal plans to meet them.

Summary

Complex carbohydrates are molecules made up of three or more sugars. The body digests these types of carbohydrate more slowly than simple carbohydrates, which consist of one or two sugars.

The two main dietary categories of complex carbohydrates are fiber and starch. Complex carbohydrates have many health benefits including improved digestion, reduced constipation, and decreased risk of colorectal cancer.

Talk with your doctor about your medical history and dietary needs. Together, you can put together an eating plan that includes the complex carbohydrates and other nutrients you need to meet your health goals.

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Medical Reviewer: Adrienne Seitz, MS, RD, LDN
Last Review Date: 2022 Jun 28
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