Complex carbohydrates are longer, more slowly digested chains of sugars that provide steady energy and more nutrients than simple sugars. They are often recommended as the main source of dietary carbs.
Basic definition
Complex carbohydrates are made of three or more sugar molecules linked together, forming starches and fibers rather than single or double sugars. These longer chains take more time for the body to break down, so they raise blood sugar more gradually than simple carbohydrates.
Types and structure
Nutrition science usually groups starch and fiber as complex carbohydrates, while simple carbs are the basic sugars. Chemically, complex carbs are polysaccharides such as starch, glycogen, and many forms of dietary fiber.
Food sources
Common food sources of complex carbohydrates include whole grains (like brown rice and whole‑wheat bread), legumes (beans, lentils, peas), starchy vegetables (potatoes, corn), and many fruits and non‑starchy vegetables. These foods typically also contain vitamins, minerals, and fiber that support overall health.
Health effects
Because complex carbs digest more slowly, they help provide sustained energy and can improve fullness compared with simple sugars. Health organizations often recommend choosing complex carbohydrates and limiting refined sugars to support better blood sugar control and reduce chronic disease risk.
