Nutrition information per serving of one medium sweet potato: 

Calories:  130
Calories from fat:  0.39 g
Protein:  2.15 g
Carbohydrate:  31.56 g
Dietary Fiber:  3.9 g
Sodium:  16.9 mg
Potassium:  265.2 mg
Calcium:  28.6 mg
Folate:  18.2 mcg
Vitamin C:  29.51 mg 
Vitamin A:  26081.9 IU
Source: National Agricultural Library (NAL), part of the Agricultural Research Service of  the US Department of Agriculture.

• CSPI ranked sweet potatoes number one in nutritional of all vegetables.

• Low Glycemic Index foods, like sweet potatoes, cause a gradual rise in blood sugar and make on feel satisfied longer.

• CSPI ranked sweet potatoes at 184 in nutritional value, more than 100 points ahead of baked Idaho potato, spinach or broccoli.

• As the body ages, it requires fewer calories, while at the same time needing to maintain or possibly even increase its vitamin and mineral requirements.

• Sweet potatoes rank significantly lower than white potatoes in the glycemic index, which explains why both carb-counting diets encourage substituting sweet potatoes for Idaho potatoes.

• Vitamin C is associated in increases in blood levels of “good” cholesterol, which lowers the risk of heart disease and decreases in levels of “bad” cholesterol.

• Sweet potatoes provide twice the recommended daily allowance of vitamin A and more than one-third the requirements for vitamin C.

• Vitamin A is necessary for strong tissues and is required to maintain healthy immune system that develops resistance to infection. Vitamin A also protects the body from cardiovascular disease and lowers the risk of stroke.

• Contains four times the daily recommended amount of beta-carotene

• Sweet potatoes are one of the greatest sources for dietary fiber, especially when eaten with the skin.

• There is more fiber in one sweet potato than in a bowl of oatmeal.

• Source of Vitamin B6, Iron, Potassium and Fiber

• Virtually No Fat

• Low Sodium

• Strokes are less common among vegetable eaters because of potassium.

• Potassium in sweet potatoes help maintain a fluid and electrolyte balance in the body cells, as well as normal heart function, nerve function and blood pressure.

• Folate in sweet potatoes help reduce homocysteine levels, a chemical capable or destroying the circulatory system that causes heart attacks.

• Director of Cancer Prevention and Control of the National Cancer Institute believe fiber may increase bulk in the colon that dilutes possible cancer promoting substances that are found in food or formed during digestion.

• Sweet potatoes are rich in soluble fiber, notably pectin, which helps to lower total and LDL (“bad”) cholesterol

• The Center for Public Interest (CSPI) ranks the sweet potato as one of the most nutritious vegetables. The sweet potato is also an important source of vitamin B6, iron, potassium and fiber.

• Sweet potatoes contain virtually no fat and are low in sodium.

• Sweet potatoes stand out from nuts and avocados as a source of vitamin E because they are fat free. Most vitamin E-rich foods are fatty, such as vegetable oils.

• Sweet potatoes help to promote a healthy digestive tract. They are also a substantial source of dietary fiber, especially when eaten with the skin. There is more fiber in one sweet potato than in a bowl of oatmeal.

• Fiber may also lower your risk of colon cancer, says Peter Greenwald, MD, director of the Division of Cancer Prevention and Control of the National Cancer Institute. Experts believe that fiber may increase bulk in the colon, thereby "diluting" possible cancer promoting substances (carcinogens) that are found in food or formed during digestion.

• Sweet potatoes, or yams, actually fit perfectly into a low-carb lifestyle—with major nutritional bonuses to boot.

• The sweet potato is a complex carbohydrate that provides twice the recommended daily allowance of vitamin A and more than one-third of the requirements for vitamin C.

• Vitamin A in sweet potatoes is necessary for strong tissues and is required to maintain a healthy immune system function and develop resistance to infection. It also protects the body from cardiovascular disease and lowers the risk of stroke.

• The National Cancer Institute recommends that people eat at least five servings of fruit and vegetables a day, especially vegetables that are rich in vitamins A and C (like sweet potatoes).

• Vegetables and fruits contain more than 100 beneficial vitamins, minerals, fibers and other substances, including phytochemicals (chemical compounds such as carotenoids, flavonoids, terpenes, sterols, indoles and phenols, created by plants).

• Vitamin C has been associated with an increase in blood levels of "good" cholesterol, which lowers the risk of heart disease, and a decrease in the levels of "bad" cholesterol, which raises the risk.

• Some fruits and vegetables are rich in soluble fiber, notably pectin, which helps lower total and LDL ("bad") cholesterol. These include apples, citrus fruit, berries, carrots, apricots, prunes, cabbage, sweet potatoes, and Brussels sprouts. If you eat at least five servings a day, you'll see an extra drop in your cholesterol level beyond the effect of a low-fat diet. UC Berkeley Wellness Letter January 2001

• Stroke is less common among vegetable eaters, possibly because of the vegetables' potassium. Source: Nutrition Action Health Letter, December 1996

• As the body ages, it often requires fewer calories, while at the same time needing to maintain or possibly even increase its vitamin and mineral requirements. Source: AARP Webplace

• Approximately 51 million Americans, more than one-quarter of all adults and one in five children, are obese. The tendency toward obesity is fostered by our environment: lack of physical activity combined with high-calorie, low-cost foods. Source: American Obesity Association

• Obesity is the second leading cause of unnecessary deaths. Each year, obesity causes at least 300,000 excess deaths in the U.S., and healthcare costs of American adults with obesity amount to approximately $100 billion. Source: American Obesity Association

• Losing weight requires physical activity and healthy eating for life. Eating right doesn't mean completely giving up cookies and cake. It just means eating them in moderation while including more nutrient-rich foods and low-fat meals in your diet.

• Low-fat foods must contain less than three grams of fat per serving. Light foods must contain one-third fewer calories than the regular version contains. But beware: fat-free and low-fat does not necessarily mean low calorie. Fat-free foods often contain high amounts of added sugar or sodium to make up for the flavor that is lost when the fat is cut.

• In 2004, nearly 12 million Americans are counting carbohydrates as part of the South Beach and Atkins diet plans. Sweet potatoes are introduced in the later phases of these diets as an acceptable food because they are nutrient-rich. Sweet potatoes rank significantly lower than white potatoes in the glycemic index, which explains why both carb-counting diets encourage substituting yams for Idaho potatoes.

• The Atkins Diet recommends introducing 10 grams of carbs in Phase 3 of the diet plan. Sweet potatoes have 10 grams of carbohydrates for every 1/4 cup. Sweet potatoes are on the safe list as a great substitute for other starches such as rice, potatoes and corn.

• Carb counters must constantly contend with a pesky detail called the glycemic index (GI). High GI foods raise blood sugar quickly - then the individual crashes, feels hungry, if not famished, and the eating cycle begins. Low GI foods cause a gradual rise in blood sugar and make one feel satiated longer. For the carbohydrates among these foods, they've taken on the nomenclature of "good" and "bad" carbs. Asparagus—good carb. White potatoes—bad carb. But all potatoes are not created equal. Among root vegetables, sweet potatoes offer the lowest GI rating. That's because the sweet potato digests slowly, causing a gradual rise in blood sugar. It's time to move sweet potatoes to the "good" carb list. Many of the most popular diets these days have already.

• Potassium in sweet potatoes helps maintain fluid and electrolyte balance in the body cells, as well as normal heart function, nerve function and blood pressure. Source: Encyclopedia of Nutritional Supplements.

• Infant malnutrition is a serious problem in many developing countries. A national health and demographic survey found that over 25 percent of children under the age of five suffer from chronic malnutrition. The International Potato Center (CIP) believes there is a good potential for improving the diet, and thereby a child’s nutritional status, by incorporating sweet potatoes into the diet. Source: Development of a Sweet Potato-Based Weaning Food for Poorly Nourished Children Six Months to Three Years Old, CIP Program Report 1997-98.

• Folate in sweet potatoes helps reduce homocysteine levels, a chemical capable of destroying the circulatory system and causing heart attacks. Heart disease is the #1 cause of death in humans and claims nearly one million American lives annually.