Sweet potatoes pack a powerful nutritional punch. They have got over 400% of your daily needs for vitamin A in one medium spud, as well as loads of fiber and potassium. They have got more grams of natural sugars than regular potato but more overall nutrients with fewer calories.
Despite the terms sweet potato and yam often being used interchangeably, they are actually not even botanically related. Yams are almost exclusively grown in Africa and are more dry and starchy compared to a sweet potato. So how did these two vegetables become so intertwined?
There are two different varieties of sweet potatoes, firm and soft. When soft sweet potatoes were being cultivated in the Americas, African slaves began calling them yams because of their resemblance to their familiar native vegetable. The name caught on as a way to distinguish between the two types of sweet potatoes. Today, you are unlikely to find a true yam in the grocery store unless you are shopping in an international market.
This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular foods. It provides a nutritional breakdown of the sweet potatoes and an in-depth look at their possible health benefits, how to incorporate more sweet potatoes into your diet and any potential health risks of consuming them.
Possible health benefits of sweet potatoes
Sweet potatoes pack a powerful nutritional punch. They have got over 400% of your daily needs for vitamin A in one medium spud, as well as loads of fiber and potassium.
Consuming fruits and vegetables of all kinds has long been associated with a reduced risk of many adverse health conditions.
Many studies have suggested that increasing consumption of plant foods like sweet potatoes decreases the risk of obesity, diabetes, heart disease and overall mortality while promoting a healthy complexion, increased energy, and overall lower weight.
Sweet potatoes are considered low on the glycemic index scale, and recent research suggests they may reduce episodes of low blood sugar and insulin resistance in people with diabetes. The fiber in sweet potatoes makes a big difference too. Studies have shown that type 1 diabetics who consume high-fiber diets have lower blood glucose levels and type 2 diabetics may have improved blood sugar, lipids and insulin levels. One medium sweet potato provides about 6 grams of fiber (skin on).
The Dietary Guidelines for Americans recommends 21-25 grams of fiber per day for women and 30-38 grams per day for men, which most people do not reach.
Maintaining a low sodium intake is essential to lowering blood pressure, however increasing potassium intake may be just as important. According to the National Health and Nutrition Examination Survey, fewer than 2% of US adults are meeting the daily 4,700 mg recommendation for potassium.3 One medium sweet potato provides about 542 milligrams.
Also of note, high potassium intake is associated with a 20% decreased risk of dying from all causes.7
Among younger men, diets rich in beta-carotene may play a protective role against prostate cancer, according to a study conducted by the Harvard School of Public Health's Department of Nutrition.4 Beta-carotene has also been shown to have an inverse association with the development of colon cancer in the Japanese population.3
Digestion and regularity
Because of its high fiber content, sweet potatoes help to prevent constipation and promote regularity for a healthy digestive tract.
For women of childbearing age, consuming more iron from plant sources appears to promote fertility, according Harvard Medical School's Harvard Health Publications. The vitamin A in sweet potatoes (consumed as beta-carotene then converted to vitamin A in the body) is also essential during pregnancy and lactation for hormone synthesis.
Plant foods like sweet potatoes that are high in both vitamin C and beta-carotene offer an immunity boost from their powerful combination of nutrients.
Choline is a very important and versatile nutrient in sweet potatoes that helps with sleep, muscle movement, learning and memory. Choline also helps to maintain the structure of cellular membranes, aids in the transmission of nerve impulses, assists in the absorption of fat and reduces chronic inflammation.6
In a study published by the Journal of Medicinal Food, purple sweet potato extract was found to have positive anti-inflammatory and antilipogenic effects as well as free radical scavenging and reducing activity.
According to Duke ophthalmologist Jill Koury, MD, vitamin A deficiency causes the outer segments of the eye's photoreceptors to deteriorate, damaging normal vision. Correcting vitamin A deficiencies with foods high in beta-carotene will restore vision.5
Also of note, the antioxidant vitamins C and E in sweet potatoes have been shown to support eye health and prevent degenerative damage.
A higher intake of all fruits (3 or more servings per day) has also been shown to decrease the risk of and progression of age-related macular degeneration.
On the next page we look at the nutritional breakdown of sweet potatoes, how to incorporate more sweet potatoes into your diet and the possible health risks of consuming sweet potatoes.