Complex carbohydrates (or polysaccharides) are built from single-unit sugars joined in long chains. Two types of complex carbohydrates are particularly important for nutrition: 1  Starch: Starch is a polysaccharide that plants use to store energy.2  Dietary Fiber: Dietary fiber is found in plants as cellulose, pectin, and lignin.any foods contain carbohydrates: There are two types of carbohydrates, simple and complex. Most of your carbohydrates should come from complex carbohydrates. 1  One slice of bread: 15 grams. 2  1/4 bagel: 15 grams. 3  One cup raw leafy vegetables: 5 grams. 4  One medium apple or orange: 15 grams.