Diet diary: A sweet potato for weight watchers and diabetics
DESPITE its name, sweet potato is not related to the potato family and is quite different nutritionally too. While the potato is a tuber or a thickened stem, the sweet potato is a storage root and loaded with nutrients, has made it to the list of top 10 diabetes super foods by the American Diabetes Association.
Though its origin lies in Latin America, Asia is its largest producer. Its importance is growing and it is the sixth most important food crop after rice, wheat, potatoes, maize and cassava. High in starch and fibre, the nature of carbohydrates differs from that in potatoes. Its high fibre content contributes to a lower glycemic index 44, which is almost half of potatoes (glycemic index 80). This property makes the sweet potato a useful carbohydrate source for weight watchers and diabetics. According to a 2004 study led by University of Vienna associate professor Dr Berhhard Ludvik and published in the journal Diabetes Care, type 2 diabetic patients treated with sweet potato saw significant decreases in fasting blood glucose levels and overall improvement in glucose control. Sweet potato when eaten with the skin has more fiber than oatmeal.
Cooking methods also affect the glycemic index of a sweet potato. For diabetics, certain cooking methods are more conducive to managing blood sugar levels. Boiled or mashed sweet potatoes, for instance, are not recommended as they are digested faster, thus increasing their glycemic index and possibly causing blood sugar levels to spike. Similar to fibre, fat will slow the rate of digestion and therefore maintain the low glycemic index, so a cooking method for sweet potatoes that is good for diabetics is sautéing in oil or roasting with the skins on. Sweet potato comes in varieties with skin and flesh color that range from white to yellow, orange, and deep purple.
According to the American Diabetes Association, apart from high fibre, sweet potato has antioxidant nutrients like vitamin A, vitamin C, zinc, and other micronutrients like potassium, magnesium, iron and vitamin B, which all help in good diabetes management and prevention of diabetes complications such as heart attacks and stroke.
Orange-fleshed sweet potato is an important source of beta-carotene, the precursor to Vitamin A. Just 125g of fresh sweet potato from orange-fleshed varieties contain enough beta-carotene to provide the daily pro-vitamin A needs of a preschooler. One medium (100 gms) sweet potato, baked with the skin, has about four times the recommended daily allowance (RDA) of Vitamin A and almost half the recommendation for Vitamin C. Nutrients in sweet potato are also useful for people with obesity, high cholesterol, high blood pressure and promotion of good health in general. A 2011 animal study conducted at School of Medicine and Life Sciences, Zhejiang University City College, China, reported that purple sweet potato flavonoids can decrease the blood glucose and lipids levels.
Staple food source for many ancient populations, sweet potato has also been found to have special cancer preventing properties, which are present in the purple-fleshed sweet potato. Anthocyanins, which give the purple colour to sweet potatoes are powerful bioavailable antioxidants, which are utilized efficiently by the body. Other nutrients, which possess anti-cancer properties of sweet potato include high amounts of vitamin A, which contribute the orange colour to the orange-fleshed sweet potato.
Overall, sweet potatoes are a healthy source of carbohydrates. Remember to watch your portions and substitute these for other carbohydrates and don’t go overboard!