Health Benefits of Sweet Potatoes (Purple / Orange Varieties)
Sweet potatoes – which come in many colors including purple, orange, yellow and white – are a versatile food that can be used to add that wonderful sweet flavor to everything from soups to smoothies. But sweet potatoes are not only tempting to the taste buds, they are also good for you. From anti-diabetic and antioxidant properties to prevention of eye-related conditions and cancer, the potential health benefits of sweet potatoes are wide and varied. Keep reading to get the details.
Both Orange and Purple Sweet Potatoes Contain Eye Health Protecting Compounds
Like many other orange vegetables, orange-fleshed sweet potatoes are loaded with carotenoids. Consumption of foods rich in carotenoids has been associated with a number of health benefits, but they are perhaps best known for their eye health protecting properties. They have been shown, among things, to improve night vision, delay the onset of age-related macular degeneration, prevent the development of cataracts, and reduce the risk of retinitis pigmentosa.
Also purple-fleshed potatoes may be good for your eyes. These funky looking root vegetables get their purple color from anthocyanins, flavonoid pigments that also give superfoods like maqui berries, black raspberries, and blueberries, red cabbage. Research suggests that anthocyanins may promote healthy vision in several ways, such as by boosting circulation within the capillaries of the retina, improving night vision, reducing the risk of retinopathy in diabetics, and providing protection against age-related macular degeneration.
Purple Sweet Potato – An Antioxidant-Rich Superfood
All sweet potatoes have antioxidant properties, but according to a study published in the journal Food Chemistry, purple sweet potatoes are the winner when it comes to antioxidant power. This study measured the in vitro antioxidant capacity of sweet potatoes with five different flesh colors – white, cream, yellow, orange and purple – using the Oxygen Radical Absorbance Capacity (ORAC) method.
Purple-fleshed sweet potatoes had the highest ORAC value (27.2 μmol TE/g), indicative of high antioxidant capacity, while the white-fleshed Xushu 18 genotype had the lowest value (2.72 μmol TE/g). This is not surprising considering that anthocyanins, the flavonoid pigments that give purple sweet potatoes their distinctive color, have been shown to exert extremely strong antioxidant activities in vitro, even stronger than the vitamin E analogue Trolox.
Protection Against Certain Types of Cancer
A Japanese study published in the June 2005 issue of the Journal of Epidemiology analyzed potential risk factors for kidney cancer, including life style and dietary habits, and found that consumption of sweet potatoes, taro, and regular potatoes was associated with a reduced risk of kidney cancer, while consumption of fatty foods and black tea seemed to increase the risk.
In another large-scale study, published in the February 1995 edition of the Japanese Journal of Cancer Research, consumption od sweet potatoes, along with a handful of other foods such as regular potatoes, was associated with a decreased risk of breast cancer in pre-menopausal women.Yet another study, published in The Journal of Toxicological Sciences in February 2002, investigated the effects of purple sweet potato anthocyanins and red cabbage anthocyanins in rats with colorectal cancer, and found that both extracts exerted anti-cancer effects in the rats.
Anti-Diabetic Activity of Sweet Potatoes
Intrigued by the traditional use of sweet potato as a treatment for diabetes in Japan, a team of Japanese researchers set out to scientifically investigate the effects of sweet potato in rats with hyperinsulinemia. Often associated with type 2 diabetes, hyperinsulinemia is characterized by excess levels of insulin circulating in the blood.
Three weeks into the study, hyperinsulinemia had decreased by 23% in the rats treated with sweet potato, and the downward trend continued until the end of the study. The sweet potato treatment was also found to improve glucose tolerance, a further indication of the potential anti-diabetic properties of sweet potato. This study used white-fleshed sweet potato and appeared in the Biological & Pharmaceutical Bulletin in January 2000.
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