Polecam:
Health Benefits
You might be surprised to discover the nutritional wallop packed by a seemingly ordinary spud. Both white and sweet potatoes contain fiber, vitamins, minerals, and other compounds that can contribute to a healthy diet.
White Potatoes
Common white-, red- russet-, purple- and yellow-skinned potatoes have been found to contain a variety of phytochemicals, such as phenolic plant compounds, polyphenolic flavonoids, and carotenoids, which may reduce oxidative stress and thus lessen certain degenerative diseases. However, s ince there are many different kinds of potatoes available, the question is: are they equal in terms of health benefits?
Phenolic plant compounds reportedly have antimicrobial effects and can fight cancer and improve both cholesterol and blood sugar levels. Recent tests(1) have revealed that the highest amounts of these compounds are found in red- and purple-colored potatoes. In one study, the range of the phenolic content between potatoes varied by as much as 171-fold in 100 grams of a fresh potato—the lowest being found in Kennebec potatoes at 1.03mg phenolics, and the highest in Purple Peruvian potatoes at 171mg phenolics.
Interestingly, the color purple on potatoes actually stems from anthocyanins, a subclass of flavonoids, which in turn are a subclass of polyphenols. They are powerful antioxidants that are known for anti-inflammatory, anti-mutagenic, and cardioprotective effects. It is believed that eating foods that contain anthocyanins may improve the overall antioxidant defense status of human plasma.
A number of animal studies suggest that potatoes also have potentially antioxidative and blood lipid-lowering effects and thus benefit cardiovascular health. The effects are thought to stem from both phytochemical and fiber content. Since the potato skin contains a large percentage of its antioxidants and fiber, we hope you’ll add more unpeeled potatoes to your favorite recipes!
Sweet Potatoes
Readily available sweet potatoes are a rich source of beta-carotene, an important antioxidant often associated with yellow and orange fruits and vegetables. Our body uses it as a precursor for vitamin A, which is vital for vision, the reproductive system, and the growth, development and differentiation of tissues and bones .
In a study(2) published in 2008 by the University of Vienna, Austria, 27 type 2 diabetes patients received either a placebo or 2-gram tablets of an Asian white-skinned sweet potato (Caiapo) twice a day for five months. In the group that received the sweet potato tablets, the researchers found significantly lowered fasting glucose and triglyceride values as well as an increase of a hormone called adiponectin—indicating a better insulin sensitivity. In addition to these antidiabetic effects, this group also experienced a decrease in a protein called fibrinogen, which suggests that sweet potatoes also may have antiatherosclerotic effects. Other studies(3) have shown that sweet potatoes and their leaves (also used as a vegetable) may have antioxidative, antimutagenic, and chemopreventive effects as well.
Curious Fact: Have you ever wondered why potatoes and sweet potatoes turn brown after being cut or peeled? Phenols, the same compounds that benefit our health, cause the browning in a complex enzymatic reaction involving amino acids, oxygen and enzymes.
Nutritional Facts
In addition to containing lots of vitamin C and health-beneficial phytochemicals, white-, yellow- and red-skinned potatoes are good sources of vitamin B6 while sweet potatoes are high in vitamin A. All varieties of potatoes provide dietary fiber, most of which is found in the skin. In the nutritional facts table(4) provided below, the values are given for one cup of raw potatoes with skin:
Nutritional Values Russet Potato Red Potato Sweet Potato
Calories 118kcal 105kcal 114kcal
Carbohydrates 27.1g 23.9g 26.8g
Dietary Fiber 1.9g 2.5g 4g
Protein 3.2g 2.8g 2.1g
Fat 0.1g 0.2g 0g
Water 118g 121g 103g
Main Vitamins B6 & C C & B6 A & B6
Main Minerals Potassium Potassium Manganese & Potassium
Tips on Selecting the Best Potatoes
Potatoes come with many different flesh and skin colors, ranging from white to pink, yellow, orange and purple. In many countries, you’ll find that they are available year-round. However, in the U.S., freshly harvested young or immature potatoes, sometimes called “new” potatoes, are available during the spring and summer, while mature potatoes are not available until they are harvested in the fall.
When given a choice, always opt for the firmest potatoes. When buying white potatoes, such as Russets, or red ones, such as Red Pontiacs, you should avoid the ones with green spots, sprouting, or any kind of bruising. When exposed to light, potatoes develop green spots, which contain a substance called solanine that not only tastes bitter, but is also poisonous. Sprouting indicates the potato is not fresh, and bruised potatoes rot easily. Also, make sure that prepackaged potatoes show no signs of dampness. If you store them in a cool, dark and dry place at home at temperatures of about 45˚–50˚F, they can stay fresh for up to several weeks.
The versatile sweet potatoes—which taste great in both main dishes and sweet desserts—also need to be stored dry, ideally in temperatures ranging from 55˚–65˚F. When shopping for sweet potatoes look for firm roots without bruises or cracks. Flesh colors can range from white to yellow, orange, red and purple. Like white potatoes, they’re available year-round, although they are freshest after their harvest in fall and winter. Sometimes, sweet potatoes in U.S. grocery stores are confusingly called yams. However, real yams are relatively rare in the US ; they’re generally sweeter than sweet potatoes and can grow many feet in length.
Oraz:
The sweet potato, Ipomoea batatas, is a nutritious and flavorful plant. It is a tuber that belongs to the morning glory family and is mostly cultivated in the southern United States, East Indies, Philippines, Oriental countries and the south of Europe. The sweet potato is often mistakenly called a yam, which is an entirely different plant species grown only in tropical climates.
Types
There are hundreds of varieties of sweet potatoes, which can be classified as moist-fleshed or dry-fleshed varieties. The distinction is based on mouthfeel, not moisture. Moist-fleshed, or soft, sweet potatoes are often orange. Dry-fleshed, or firm, sweet potatoes are usually white or yellow. The flesh can range from white to yellow to orange-red. The skin is smooth and thin, and can be white, purple, yellow, red or brown.
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Nutrition
For only 160 calories, a large sweet potato has an abundance of nutrition. Baked in its skin without added salt or sweetener, it is a good source of magnesium, phosphorus, potassium, niacin and the B vitamins, in terms of daily value provided, based on Dietary Reference Intake values. The sweet potato is an excellent source of manganese and vitamins A, B-6 and C. The stand-out nutrient in sweet potatoes is vitamin A; one large potato has more than twice the recommended daily value.
Vitamin A
Sweet potatoes are rich in beta-carotene, which makes their flesh yellow, orange or red. Beta-carotene is one of many carotenoids that form vitamin A after being absorbed in the body. Beta-carotene is an antioxidant and may protect against chronic disease and reduce cancer risk, according to Medline Plus. While all sweet potatoes contain similar amounts of the same nutrients, the notable difference among the varieties is the content of beta-carotene. More beta-carotene is available in orange-fleshed than in white- or yellow-fleshed varieties.
Tips
For optimal freshness and nutrition, store sweet potatoes in a cool, dry place and use them within a week or two of purchase. Do not use bruised sweet potatoes. Wash them immediately before use. Choose orange-red fleshed varieties for greater beta-carotene. Bake, steam, boil, roast or mash them. Puree them for soups. Sweet potatoes are plentiful and seasonal from late August through November. Cook them in bulk and freeze them for year-round use.
References
“The Oxford Companion to Food”; Alan Davidson; 2006
“Encyclopedia of Food”; Artemas Ward; 1941
USDA Nutrient Data Laboratory: sweet potato, baked, cooked in skin, without salt
“Journal of Food Technology in Africa”; Influence of Age, Farming Site, and Boiling on Pro-Vitamin A Content in Sweet Potato (Ipomoea batatas (L.) Lam.) Storage Roots; L.M. K’osambo, et al.; July-September 1999
MedlinePlus: Vitamin A
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