Sweet potato – the ultimate wonder food

Steamed sweet potatoes

Steamed sweet potato is one of my favourite breakfast items, it is easy to prepare (just wash and steam the whole tuber until soft), delicious to eat, and most importantly, packed with energy and loads of nutritional value!

Sweet potato is the tuberous root of a plant scientifically known as Ipomoea batatas.  The edible root of this plant comes in many colours. The skin can be yellow, orange, red, brown, purple, and beige; and the colours of the flesh range from beige to white, red, pink, violet, yellow, orange, and purple [1].

Orange sweet potatoes

Nutritional values

Nutritionally, sweet potato is considered a high-carb food with a caloric ratio of 93% carbohydrates, 6% protein, and 1% of fats [2]. Some people may frown upon high-carb food due to the link of high carbohydrate consumption to the risk of obesity [3]. However, one should distinguish between the good carbs and the bad carbs. The bad carbs are sugar and refined carbohydrates that are easy to digest and cause an immediate increase in blood sugar (high glycemic index) [4].  Indeed, over consumptions of bad carbs have been suggested as the culprit of modern diseases such as metabolic syndrome. Good carbs, instead, are complex carbohydrates, high in dietary fibre, which can slow down the absorption of the carbohydrates and avoid the spike in blood sugar (low glycemic index) [4]. Sweet potato is one such good carbs.

Glycemic index of sweet potato compared to other carbs. (Source: http://haleo.co.uk/plant-based-food/carbohydrates/)

 

Besides being a good source of energy, sweet potato is also the starchy vegetable that contains the most vitamin A, predominantly in the form of beta-carotene, a vitamin A precursor [5]. 200g of sweet potato contains 38433 IU of vitamin A, which is 769% of the daily value requirement of an adult [2]. Sweet potato is also rich in vitamin C and B6, B5, B1-3, as well as minerals including manganese, potassium, copper, magnesium, and phosphorus. It provides over 90% of nutrients per calorie required for most people [1].

Heath Benefits

Besides being a valuable food source, the plant of sweet potato has also been used in traditional medicine all over the world to treat diseases such as diabetes, hypertension, dysentery, constipation, fatigue, arthritis, rheumatoid diseases, meningitis, kidney ailments, and inflammations [1].

Purple sweet potato – an excellent antioxidant food

Modern scientific analysis has found sweet potato to contain many phytochemicals that can exert antioxidant, antibacterial, and anticancer activities. Biologically active compounds in sweet potato also have health promoting effects on the cardiovascular and immune systems [1]. There are also studies indicating that sweet potato can help to lower blood sugar and cholesterol levels among diabetic patients [6]. The indigenous peoples of Papua New Guinea (PNG) Highlands who consumed mainly sweet potato as its staple food in their traditional diet is known to have little or no hypertension or rise of blood pressure with age [7]. Regularly consume sweet potato can also be beneficial for visual health due to its anthocyanin contents [8].

Homemade sweet potato fries – a healthier alternative to commercial french fries

Summary

Here is a summary of the goodness of sweet potato:

  1. Good complex carbohydrate food rich in dietary fibre.
  2. An excellent source of vitamin A (beta-carotene), vitamin C, and potassium.
  3. Contains phytochemicals with antioxidant, antibacterial, and anticancer activities.
  4. Good for cardiovascular health, immune system, vision, and blood sugar control.

Hence, sweet potato is a functional food to include in any healthy diet.

References

 

[1]        R. Mohanraj, S. Sivasankar, Sweet potato ( Ipomoea batatas [L.] Lam) – A valuable medicinal food: A review, J. Med. Food. 17 (2014) 733–741. doi:10.1089/jmf.2013.2818.

[2]        Sweet potato, cooked, baked in skin, without salt [Sweetpotato] Nutritional facts and calories, SELF Nutr. Data. (n.d.). http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2667/2 (accessed January 22, 2018).

[3]        A. Malhotra, T. Noakes, S. Phinney, It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet, Br. J. Sports Med. 49 (2015) 967–968. doi:10.1136/bjsports-2015-094911.

[4]        J. Brand-Miller, J. McMillan-Price, K. Steinbeck, I. Caterson, Carbohydrates–the good, the bad and the whole grain., Asia Pac. J. Clin. Nutr. 17 Suppl 1 (2008) 16–19.

[5]        P.J. van Jaarsveld, M. Faber, S. a Tanumihardjo, P. Nestel, C.J. Lombard, A.J.S. Benadé, Beta-carotene-rich orange-fleshed sweet potato improves the vitamin A status of primary school children assessed with the modified-relative-dose-response test., Am. J. Clin. Nutr. 81 (2005) 1080–1087.

[6]        C.P. Ooi, S.C. Loke, Sweet potato for type 2 diabetes mellitus, Cochrane Database Syst. Rev. (2013) CD009128. doi:10.1002/14651858.CD009128.pub3.

[7]        J.J. Carvalho, R.G. Baruzzi, P.F. Howard, N. Poulter, M.P. Alpers, L.J. Franco, L.F. Marcopito, V.J. Spooner, A.R. Dyer, P. Elliott, Blood pressure in four remote populations in the INTERSALT Study., Hypertens. (Dallas, Tex.  1979). 14 (1989) 238–46. doi:10.1161/01.HYP.14.3.238.

[8]         M. Sun, X. Lu, L. Hao, T. Wu, H. Zhao, C. Wang, The influences of purple sweet potato anthocyanin on the growth characteristics of human retinal pigment epithelial cells., Food Nutr. Res. 59 (2015) 27830. doi:10.3402/FNR.V59.27830.

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