Sweet potatoes are a traditional fall food, often gracing the family Thanksgiving menu. Today, the average American eats about four pounds of sweet potatoes a year, down from an average of 30 pounds in 1920. Given the nutritional density of the affordable, easy-to-prepare sweet potato, our ancestors had the right idea: Sweet potatoes arent just for covering with marshmallows at the holidays.Tufts HNRCA scientist Elizabeth Johnson, PhD, says,Eating sweet potatoes can help cover a lot of bases nutritionally. And all the foods rich in carotenoids add so much color and diversity to your diet, which is also a benefit.The sweet potato (Ipomoae batatas) was domesticated at least 5,000 years ago in its native South America. It’s now cultivated worldwide in tropical and temperate regions, and is a staple food in many cultures. Sweet potatoes can be found in a range of colors from pale orange to deep red and purple, although more exotic varieties may be difficult to find in US supermarkets.At only 180 calories per one cup of cooked sweet potato, and on average around $1 per raw pound, sweet potatoes won’t break the scales or the bank account. With a whopping 7 grams of fi- ber in that one cup, sweet potatoes star when it comes to satiety: Regular white potatoes average just 2 grams of fiber per cup, and even cooked oatmeal packs only 3 grams in a cup. No wonder adding sweet potato to a meal helps you feel full throughout the day.Increasing intake of dietary fiber is also one key step in a heart-healthy diet, as soluble fiber has been shown to decrease LDL cholesterol levels. High- fiber foods, such as whole grains or sweet potatoes, can also help regulate blood-sugar levels. With a glycemic load of only 17, one serving of sweetpotatoes is a smart stand-in for white starches like pasta or bread that cause more dramatic swings in blood sugar.Another heart-healthy reason to eat sweet potatoes is their potassium content-950 milligrams in one cup. Although often overlooked as a nutrient, potassium plays an important role in regulating blood pressure. With the average American eating well below the recommended daily amount, sweet potatoes are a simple way to boost potassium intake.
| I Yam What I Yam Is it a yam or a sweet potato? Both the tan sweet potato with creamy yellow interior and the copper-skinned, deep-orange- fleshed vegetable sold as a yam are botanically sweet potatoes. The true yam commonly eaten in Africa is seldom sold in US markets. |
Like most deeply colored foods, sweet potatoes are also a good source of many vitamins and other nutrients. Contrary to popular belief, vitamin C isn’t found only in tart and tangy foods: Sweet potatoes contain 65% of the daily value, or 39 micrograms, in one cup. Crucial in the body as an antioxidant, vitamin C is also used to form collagen, a protein that keeps skin and nails strong and resilient.A cup of cooked sweet potato delivers almost a third of the daily value of vitamin B6, important to processes such as amino acid and lipid metabolism. B6 is also used to form many neurotransmitters, including the well-known mood regulator serotonin.The rich orange color of sweet potatoes indicates a high concentration of carotenoids, as in carrots. In particular, sweet potatoes contain beta-carotene, which the body uses to form vitamin A. One cup contains enough beta-carotene to produce a staggering 769% of the daily value, or 38,433 IUs of vitamin A, which plays key roles in vision and immune health. Vitamin A consumed in food sources as beta-carotene avoids the risk of toxicity (although it can startto give your skin an orange tint if consumed in very high amounts).Sweet potatoes are a source of another important carotenoid, lutein. Its not just the familiar vegetable thats rich in lutein, though: The leaves of the sweet potato plant, which can be used like spinach in cooking, are one of the richest sources of dietary lutein. Tufts researchers have established a link between dietary lutein and deposition in the macula of the eye, with lutein helping to protect against age-related macular degeneration (AMD).Researchers are also now looking at sweet potatoes as a source of anthocyanins, a type of phytochemical that gives fruits and vegetables a red or blue color. Anthocyanins act in nature as sunscreen for plants, protecting against the damaging effects of UV light, and also attract pollinators like birds or insects. When consumed, they have potent antioxidant properties. Although research is still in its early stages, anthocyanins are being investigated for protective effects against diseases ranging from diabetes to neurological degeneration to various cancers.Sweet potatoes, particularly varieties that have a purplish color, contain high levels of anthocyanins. They may also be a more practical source of these phytochemicals than options like blueberries or cherries. Sweet potatoes are cheaper, and can be consumed in higher amounts and on a more regular basis.
Sweet potatoes are also naturally fat-free, but if youre adding toppings, try to keep them healthy. (See recipe box on next page for some ideas.) Limit added butter and sugar and stick to nutritious add-ons like spices, olive oil or nuts. Sorry, marshmallows dont count as healthy toppings.-Victoria HoVictoria Ho is a Dietetic Intern in the Friedman Schools Frances Stern Nutrition Center.