The jewel yam, commonly available at grocery stores throughout the United States, is not a yam at all but in fact a variety of sweet potato. While this root vegetable is available year-round, the best harvest for jewel yams occurs from September through March. This vegetable has an orange flesh with a darker orange skin. The nutritional value of jewel yams makes them a go-to vegetable for good health.

One medium jewel yam — approximately 130 grams — contains about 100 calories. Many people treat sweet potatoes like regular potatoes, roasting them and adding butter and sour cream for flavor. Doing so adds 102 calories from one tablespoon of salted butter and 23 calories per tablespoon of sour cream.

The jewel yam provides you with four grams of fiber per serving assuming you are consuming the entirety of this tuber, skin and all — a good deal of the fiber resides there.

Your meal plan should include 25 to 38 grams of fiber per day to maintain the health of your digestive system. The fiber in your diet also helps lower the amount of cholesterol in your blood, control the levels of your blood sugar and may help prevent colorectal cancer.

Jewel yams contain a high level of sugar at seven grams. Despite this, the jewel yam is a low glycemic index vegetable, recommended for those with diabetes. The American Diabetes Association refers to sweet potatoes as a "superfood," suggesting diabetics replace regular potatoes with these types of sweet potatoes.

The jewel yam contains zero grams of fat, making it a good choice if you follow a low-fat diet. The majority of the calories in this sweet potato come from carbohydrates, a macronutrient your body primarily uses for energy. A 130 gram-sized jewel yam contains 23 grams of carbohydrates.

The Institute of Medicine recommends consuming 130 grams of carbohydrates each day, as well as 46 to 56 grams of protein. One jewel yam provides you with two grams of protein, so be sure to adjust your meal plan accordingly to meet your daily nutritional goals.

Including jewel yams in your diet gives you a big boost of vitamin A — one medium yam provides you with up to 90 percent of the daily recommended intake of this vitamin. This makes the jewel yam an excellent choice to maintain the health of your eyes.

Vitamin A influences both regular vision and night vision. It also plays a role in maintaining healthy skin and teeth. Jewel yams also serve as a rich source of vitamin C. One serving of jewel yams contains 52 percent of the vitamin C you need each day, as well as eight percent of the iron and calcium your body requires daily.