Sweet Potatoes

by OneGoodFoodBlog

Baked, fried, mashed, ground into flour, or sliced and baked into chips: If it seems like sweet potatoes are suddenly everywhere, it’s not in your imagination. Consumption of the sweet orange root vegetable rose nearly 42 percent between 2000 and 2016 in the United States, reaching 7.2 pounds per person. Changing dietary habits and marketing hype have fed this trend, yet how much do you really know about this versatile vegetable?

What Is the Sweet Potato Exactly? And Where Does the Root Veggie Come From?

The sweet potato (Ipomoea batatas) is a tuber belonging to the morning glory family of flowering plants. It’s different from a white potato, which belongs to the nightshade plant family and is more closely related to eggplants and tomatoes. Often, the flesh of the sweet potato is orange or yellow, but it can also be white, red, or purple. Believe it or not, sweet potato leaves are also edible.

This flexible staple food is native to the tropical regions of the Americas, and its cultivation likely dates back to prehistoric times. These days, it’s grown across the globe, with China, Nigeria, and Tanzania being top producers. Within the United States, North Carolina grows the most sweet potatoes of any state.

The terms sweet potato and yam are used interchangeably in America, but they are really not the same vegetable. Most likely that can of “candied yams” sitting in your kitchen cabinets contains cut sweet potatoes, and the list of ingredients on the label will say so — as the U.S. Department of Agriculture (USDA) requires.

Whole, unpackaged yams, which are native to Africa and Asia, are starchier and drier than sweet potatoes and belong to the Dioscoreaceae family of plants. The two are so unrelated that they don’t even belong to the same class of flowering plant. The sweet potato is a dicot, with two embryonic seed leaves; while the yam is a monocot with only one embryonic seed leaf.

So why the confusion over names? Sweet potatoes come in firm and soft varieties, and when the soft varieties were first grown commercially in the United States, the crop workers were African slaves. Given that yams are a staple crop in Africa and the soft sweet potatoes resembled them, enslaved workers called them yams. The producers and shippers followed suit to distinguish soft and firm sweet potatoes commercially.

According to the USDA, these are the nutrition facts for a medium sweet potato — 2 inches in diameter, 5 inches long when raw, and 114 grams (g) — that is baked in the skin without salt:

Calories: 103

Protein: 2.29g (4.6 percent of Daily Value, or DV)

Total fat: 0.17g

Carbohydrates: 23.61g

Total dietary fiber: 3.8g (15.2 percent DV)

Total sugars: 7.39g

Sodium: 41 milligrams (mg)

Cholesterol: 0mg

Calcium: 43mg (4.3 percent DV)

Iron: 0.79mg (4.4 percent DV)

Magnesium: 31mg (7.8 percent DV)

Phosphorus: 62mg

Potassium: 542mg (11.5 percent DV)

Zinc: 0.36mg

Vitamin C: 22.3mg (37.2 percent DV)

Thiamin: 0.12mg

Riboflavin (vitamin B2): 0.12mg

Niacin: 1.70mg

Vitamin B-6: 0.33mg

Folate: 7 µg (micrograms)

Vitamin A: 21,909 international units, or IU (438.2 percent DV)

Vitamin E: 0.81mg

Vitamin K: 2.6µg (3.3 percent DV)

Sweet potatoes are full of vitamins and minerals essential to daily health, according to the U.S. Department of Agriculture’s MyPlate guidelines, and have a number of benefits. A sweet potato is high in vitamin A, particularly in the form of beta-carotene. Eating just one of them baked in the skin will give you more than four times the recommended Daily Value of the nutrient, making it one of the richest plant sources of the vitamin there is. Vitamin A is important to the health of your vision, cells, and immune system, as well as embryonic growth.

Sweet potatoes are also great sources of vitamin C, a powerful antioxidant that plays key roles in immune system health, connective tissue development, and wound healing. Look to tubers like sweet potatoes for vitamin B6, potassium, and dietary fiber.

Sweet potato leaves are increasingly recognized as a go-to source for polyphenols, micronutrients that have been studied for their antioxidant properties. Steaming may be the best method of preserving the polyphenols in the leaves, according to a study published in September 2014 in the Journal of Agricultural and Food Chemistry.

Are Sweet Potatoes Good for Weight Loss?

Certainly, a sweet potato is a more diet-friendly starch option than a white potato. It’s lower in carbohydrates and higher in fiber (which can help you feel, and stay, full). Those benefits may help you shed pounds, but you won’t likely notice a difference on the scale just from switching to sweet potatoes. Any hopes that the sweet potato has weight-loss properties are preliminary.

A study published in December 2016 in the journal Heliyon observed that a protein contained in the wastewater made from sweet potato starch processing inhibited weight gain in mice who were fed a high-fat diet. The mice that were fed the protein had lower body weight, liver mass, cholesterol, and triglycerides, as well as higher levels of hormones that control hunger. The researchers called for human intervention studies to confirm that effect in people.

Are Sweet Potatoes Okay for People With Diabetes to Eat?

When eaten in moderation, sweet potatoes can make a healthy, type 2 diabetes-friendly substitute for white potatoes. That’s because compared with the white potato, the sweet potato is lower on the glycemic index (GI), which is a scale that measures how a food containing carbohydrates raises blood glucose levels. Foods are ranked on a scale of 0 to 100, with 100 being the GI of pure glucose (sugar). Glycemic control is an important goal for people with diabetes and with lower GI foods generally being healthier options.

A boiled sweet potato has a GI of 44 versus a boiled white potato, which has a GI of 82. But another measure gives you an even better picture of which has the ability to raise your blood sugar higher: glycemic load. That’s calculated by multiplying the GI by the number of carbohydrate grams in a serving, and then dividing that value by 100. With this formula, you’ll see that a boiled sweet potato has a glycemic load of only 11, while a boiled white potato has a glycemic load of 25.

By the way, a study published in the Journal of Nutrition and Metabolism suggested that boiling is, in fact, is the best cooking method to minimize the GI of a sweet potato.

Needless to say, adding sweeteners like honey or toppings like marshmallows will boost GI, so skip these additives and let the vegetable’s natural sweetness shine through instead. If needed, sprinkle your sweet potato with a pinch of salt and pepper — or perhaps a dash of cinnamon.

Select and handle sweet potatoes with care because they bruise easily — and that bruising can promote spoilage. Opt for ones that feel heavy for their size and have no bruises, soft spots, or sign of sprouting. Wash them and cut off any brown spots before you use them.

Store your sweet potatoes in a cool, dry, well-ventilated place (like a root cellar), but not in the refrigerator, as that will result in a hard center and bad taste. Stored and handled properly, they will last one to two weeks.

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