Sweet potato (Ipomoea batatas (L.) Lam) is the seventh most important food crop in the world (Kays, 2004). It has a high nutritional content and there is a wide range of health benefits of eating sweet potato (Mohanraj & Sivasankar, 2014). Its consumption is decreasing worldwide, however, in comparison with wheat and rice (Kays, 2004). This may be in part because potatoes are incorrectly regarded by many as an “unhealthy” food that is high in calories and fat (Camire, Kubow, & Donnelly, 2009). Some of this misconception may be due to how potatoes are prepared, for example, when they are deep-fried (Ezekiel et al. (2013). In fact, sweet potatoes can be a good source of many important nutrients and, given how widely they are cultivated and consumed, can be an important source of these nutrients around the world. Sweet potato has a similar range of nutritional benefits to white potato (Camire et al., 2009), but the levels of these nutrients tend to be higher. Sweet potato can vary in colour – beige, white, red, pink, violet, yellow, orange, and purple, and these different coloured potatoes can also provide different nutritional and health benefits (Mohanraj & Sivasankar, 2014).
In terms of sweet potato nutrition, the main component is starchy carbohydrates (Zaheer & Akhtar, 2016). Of particular importance are the high levels of resistant starch. Resistant starch is broken down very slowly during digestion, which can reduce the risk of blood sugar spiking in people with type-2 diabetes (Ezekiel et al., 2013). It also increases feelings of satiety, which can be important for weight control in people at risk of obesity (Aziz, Kenney, Goulet, & Abdel-Aal, 2009). Not only that, but sweet potato (as opposed to white potato) is actively anti-diabetic, and this is true for both the flesh and the peel. This means that it is easy to introduce sweet potato into the diet of people with type-2 diabetes as a way of helping to manage the disorder (Mohanraj & Sivasankar, 2014). When rats were given a diet high in sweet potato, they showed improved pancreatic function, lowered lipid levels, better glucose management, and decreased insulin resistance. In comparison to white potato, sweet potato contains a higher level of amylose, which helps to raise the blood sugar level slowly.
Sweet potato provides a high level of important vitamins. It is high in vitamin C, which is important for iron availability. It is also high in several B vitamins (folic acid, niacin, pyridoxine, riboflavin, thiamine, and pyridoxine), which are important for metabolism throughout the body (Camire et al., 2009). It is important to eat a diet high in B vitamins because the human body is unable to produce these or to store them (Mohanraj & Sivasankar, 2014). Sweet potatoes are also high in vitamin A, a deficiency in which can cause blindness and even death (Camire et al,m 2009). Sweet potatoes have been found to provide 100% of the RDA (recommended dietary allowance) of vitamin A and 49% RDA of vitamin C (Mohanraj & Sivasankar, 2014).
Carotenoids and flavonoids are both found in sweet potato (Brown, 2005). The orange-fleshed sweet potato may be the highest source of beta-carotene found in nature (Mohanraj & Sivasankar, 2014). While white potato does also contain carotenoids, sweet potatoes contain a much higher level. Carotenoids are antioxidants, anticarcinogens, reduce cholesterol, and protect against certain cancers (Mohanraj & Sivasankar, 2014). Flavonoids have antioxidant properties. They rid the body of oxygen radicals, so are protective against developing cancers (Andre, Kenney, Goulet, & Abdel-Aal, 2009). In terms of sweet potato vs white potato, white potato contains low levels of flavonoids, but sweet potato can contain much more. This is because the level of flavonoids is connected to the pigment of the flesh, and they are much higher in potatoes that are orange in colour (Brown, 2005). Purple sweet potato contains high levels of anthocyanins (Mohanraj & Sivasankar, 2014), which are another type of antioxidant and which are also anti-inflammatory. These can lower the health risk of heavy metals and can rid the body of oxygen radicals.
Sweet potato is also an important source of minerals. It contains 10% of RDA for iron and 15% for potassium, as well as high levels of phosphorous and calcium (Mohanraj & Sivasankar, 2014). In comparison, white potato is only a good source of potassium when the skin is also consumed (Camire et al., 2009). Potassium has the ability to support the absorption of other minerals, so is a particularly important dietary mineral. Rats who have been fed a high-sodium diet were better able to retain calcium and magnesium when they were also fed a high-potassium diet (Camire et al., 2009).
In conclusion, there are several health benefits of eating sweet potato. It contains starchy carbohydrates, with a low glycaemic index (GI), which can help lower the risk of diabetes and can also aid in diabetes management. It also contains many important vitamins and minerals, as well as phytonutrients such as carotenoids and flavonoids. There are some health benefits of sweet potato vs white potato, including higher levels of carotenoids and flavonoids, higher levels of potassium, and higher levels of amylose (which helps to release energy more slowly, leading to less chance of a blood sugar spike).
Khalid Zaheer & M. Humayoun Akhtar (2016) Potato Production, Usage, and Nutritionâ€”A Review, Critical Reviews in Food Science and Nutrition, 56:5, 711-721, DOI: 10.1080/10408398.2012.724479
Ezekiel, R., Singh, N., Sharma, S., & Kaur, A. (2013). Beneficial phytochemicals in potatoâ€”a review. Food Research International, 50(2), 487-496.
Andre, C. M., Legay, S., Iammarino, C., Ziebel, J., Guignard, C., Larondelle, Y., … & Miranda, L. M. (2014). The potato in the human diet: a complex matrix with potential health benefits. Potato Research, 57(3-4), 201-214.
Camire, M. E., Kubow, S., & Donnelly, D. J. (2009). Potatoes and human health. Critical reviews in food science and nutrition, 49(10), 823-840.
Aziz, A. A., Kenney, L. S., Goulet, B., & Abdel-Aal, E. S. (2009). Dietary starch type affects body weight and glycemic control in freely fed but not energy-restricted obese rats. The Journal of nutrition, 139(10), 1881-1889.
Mohanraj, R., & Sivasankar, S. (2014). Sweet Potato (Ipomoea batatas [L.] Lam)-A valuable medicinal food: A review. Journal of medicinal food, 17(7), 733-741.
Kays, S. J. (2004, February). Sweetpotato production worldwide: Assessment, trends and the future. In I International Symposium on Root and Tuber Crops: Food Down Under 670 (pp. 19-25).
Brown, C. R. (2005). Antioxidants in potato. American journal of potato research, 82(2), 163-172.