Plant-based foods (fruits, vegetables, whole-grain, beans, legumes) contain fibre and most contain soluble and insoluble fibre. Both types have specific health benefits: soluble fibre is contained inside plant cells and absorbs water, forming a gel-like substance that slows down the process of digestion. It also slows down the absorption of glucose and reduces absorption of LDL (unhealthy) cholesterol. Insoluble fibre is found in the cell walls of plants. Although it absorbs water, it cannot be dissolved. Acting like a natural laxative by adding bulk, insoluble fibre aids the passage of stools through the intestines, useful in the prevention of constipation and diverticulosis.
Sweet potatoes are nutritional gems: their GI is surprisingly low and their total nutritional content exceeds that of many other vegetables. They are particularly rich in beta-carotene, a carotenoid the body uses to manufacture vitamin A needed for vision, the immune response, skin and mucous membranes and to regulate cell growth, bone metabolism and hormone synthesis. If you eat a little fat (olive oil, butter) with sweet potato, you significantly increase your uptake of beta-carotene. Some people are unable to absorb beta-carotene adequately or convert it into active vitamin A and require dietary sources from fish, cod liver oil, eggs, meats, butter.