Besides simple starches, sweet potatoes are rich in complex carbohydrates, dietary fiber, beta carotene (a vitamin A equivalent nutrient), vitamin C, and vitamin B6. Pink, yellow and green varieties are high in carotene, the precursor of vitamin A.
Sweet potato varieties with dark orange flesh have more beta carotene than those with light colored flesh, and their increased cultivation is being encouraged in Africa, where vitamin A deficiency is a serious health problem. Despite the name "sweet", it may be a beneficial food for diabetics, as preliminary studies on animals have revealed that it helps to stabilize blood sugar levels and to lower insulin resistance.
The peptic substance (0.78 percent total, 0.43 percent soluble) present in fresh tubers contains uronic acid (60 percent) and methoxyl (4 to 5 percent). Other constituents include phytin (1.05 percent), two monoaminophosphatides (probably lecithin and cephalin), organic acids (oxalic acid), phytosterolin, phytosterol, resins, tannins, and coloring matter.