The Folklore. Sweet potato or yam? Most likely, it’s a sweet potato. The most common varieties of sweet potato in the U.S. have smooth orange or red skin, orange flesh, and a sweet flavor. Yams, which are rare in American grocery stores, have rough brown skin, starchy white flesh, and a neutral flavor. Yams (Dioscoreae alata) and sweet potatoes (Ipomoea batatas) are not even closely related. Confusion began in the 1930s when Southern sweet potato growers called them yams, from the African word for sweet potato, “nyami,” to distinguish their crop from regular white potatoes. Sweet potatoes are a rich and tasty source of antioxidant and anti-inflammatory nutrients.
The Facts. Despite its name, the sweet potato, a member of the morning glory family of plants, is not related to the potato (Solanum tuberosum). There are about 400 varieties in different skin and flesh colors (white, purple, yellow, orange), some round or oblong, like a potato, others long and slender with tapered ends. Common varieties like Garnet or Japanese Purple have different textures (firm and dry or soft and moist) and degrees of sweetness. One medium sweet potato has just 103 calories, yet packs 438% DV (DV=Daily Value, based on 2,000 calories/day) of vision-protecting vitamin A, 37% DV of antioxidant vitamin C, and the powerful, health-promoting plant compounds, beta carotene and anthocyanins, that give the yellow/orange and purple varieties respectively, their color.
The Findings. Antioxidant capacity of sweet potatoes is mainly due to anthocyanin and carotenoid content, consumption of which is associated with lower risk of diabetes, cardiovascular disease, cancer, and cognitive performance (Antioxidants, 2022). Orange-fleshed sweet potato ranked number one among all vegetables from a dietary point of view and nutritional perspective, according to a review of studies in different countries (Food Science & Nutrition, 2019), due in part to its significant vitamin A content, especially needed in countries with vitamin A deficiencies.
The Finer Points. Peak season for sweet potatoes is October through December, but they are available all year. Select small and medium sweet potatoes for a sweeter, moister flesh. Choose those with smooth, firm, and blemish-free skin. Store in a cool, dark, well-ventilated place, but never refrigerate them. Sweet or savory, these taters will not disappoint. Bake them whole and top with yogurt, nuts, and maple syrup, mash with regular potatoes, or cut into fries and roast.