The benefits of eating yams and sweet potatoes

A staple in many households around the world, yams and sweet potatoes are nutritious and delicious. Follow these guidelines to learn the health benefits of these sweet tubers and how to prepare them.

Deriving their name from the Senegalese word ñam ("to eat"), yams are often confused with the sweet potato. Although many varieties of sweet potato are marketed as yams in North America, true yams are native to Africa and are seldom seen in the United States or Canada. Growing up to 45 kilograms (100 pounds), they are much larger than sweet potatoes and not as rich in vitamins. They are, however, a good source of potassium and starch and are a carbohydrate staple in parts of Africa and Asia.

Sweet potatoes are also not related to the common white potato. In their own right, however, these tubers are highly nutritious, and their rich, sweet flavour belies their humble origins as a New World plant that was introduced to Europeans by Columbus and other explorers.

Like other brightly coloured orange-yellow vegetables, sweet potatoes are an excellent source of beta carotene, an antioxidant precursor to vitamin A. On average, one medium sweet potato provides more than 100 percent of the Recommended Dietary Allowance (RDA) for vitamin A, about 33 percent of the RDA for vitamin C, 20 percent of the RDA for B6, 400mg of potassium, along with folate and some iron.

Sweet potatoes also contain plant sterols, which are cholesterol-lowering compounds. When eaten with its skin, a sweet potato is an excellent source of insoluble fibre, which may help prevent constipation and diverticulosis. It also contains the soluble fibre pectin, which may help control cholesterol. Beta carotene, the carotenoid that gives colour to sweet potatoes, is a powerful antioxidant linked to lowered risk of heart disease and certain cancers.

Sweet potatoes spoil quickly, and any that have moldy spots or are shrivelled should be thrown away. Cutting away the bad spots does not always help, because an unpleasant flavour may have already spread to the rest of the potato.

• Store sweet potatoes in a cool place but not in the refrigerator; temperatures below 10°C (50°F) gives them a hard core and an off taste.
• Sweet potatoes derive their flavour from an enzyme that converts starches to sugar. As the tuber matures and is cooked, it becomes sweeter. Immediately after harvesting, sweet potatoes are cured — stored at about 85°F (30°C) for four to six days — to increase their sweetness and decrease the danger of spoiling.
• Since their skins are very thin, sweet potatoes should be treated gently.
• If peeling is necessary, it is easily done after they are cooked.
• Traditional recipes for candied sweet potatoes, a Thanksgiving basic, often call for a lot of sugar and fat. A lighter alternative is to use thickened apple juice as a glaze and to substitute pineapples for marshmallows.
• Sweet potatoes can replace white potatoes and pumpkins in a number of recipes, and mashed sweet potatoes with defatted broth or grated orange peel is a vitamin-packed side dish.

Incorporate these tubers into your regular diet to reap their health benefits.