Sweet potatoes originate from Central America and are one of the oldest vegetables known to man, having been consumed since prehistoric times. About the 16th century, sweet potatoes began to be cultivated in the southern United States, where they still remain a staple food in traditional cuisine.
It was only in the mid-20th century, that orange-fleshed sweet potato was introduced to the United States. It was called yam so as not to be confused with the older varieties of sweet potatoes. Today, sweet potatoes are grown commercially in China, Indonesia, Vietnam, Japan, India and Uganda.
As well as orange-fleshed sweet potatoes there are purple colored and white sweet potatoes too
If you see the word gold or red in the name of the sweet potato,then it will be an orange-fleshed variety. It is the intensity of the sweet potato's yellow or orange flesh color that is directly correlated to its beta-carotene content which helps our bodies to produce vitamin A. When eating such sweet potatoes, include a small helping of fat to maximize the beta-carotene. This can be some butter from grass fed cows or some extra virgin olive oil. Sweet potatoes have the ability to raise our blood levels of vitamin A (and especially in children) while carotenoids help strengthen our eyesight and boost our immunity to disease. They are powerful antioxidants that help ward off cancer.
These same antioxidants in sweet potatoes also protect against the effects of aging - including a younger looking, more radiant skin
The purple-fleshed sweet potato has important antioxidant properties and anti-inflammatory properties which, when passing through our digestive tract, may be able to lower the potential health risk posed by heavy metals and oxygen radicals.
There are many more health benefits
1. They are high in vitamin B6, helping reduce the chemical homocysteine in our bodies. Homocysteine has been linked with degenerative diseases including heart disease.
2. They are a good source of vitamin C which as well as helping to ward off cold and flu vireses, plays a vital role in bone and tooth formation, digestion as well as blood cell formation. The presence of high levels of vitamin C helps speed up wound healing, produces collagen to maintain our skin's elasticity and even helps us to cope with anxiety and stress. A further benefit of good levels of vitamin C is to protect against toxins that may be linked to cancer.
3. Many people have today learnt the importance of vitamin D which is a feel good hormone best gained from direct sunlight and vital to our overall health. Although food sources are less important, sweet potatoes will add to our supply of vitamin D.
4. Sweet potatoes also contain iron which we need in adequate amounts for metabolizing protein, energy, blood cell production, to avoid stress and to boost our immune systems.
5. They are a good source of magnesium of which many in the US are deficient but which is needed for so many body functions and to fight stress and ensure relaxation.
6. Sweet potatoes increase our levels of potassium to help regulate heartbeat and nerve signals and many other essential functions.
7. In spite of their sweet taste, the natural sugars in sweet potatoes are released slowly as a balanced source of energy rather than the unhealthy blood sugar spikes that refined sugars and sodas would cause.
8. Sweet potatoes have RS which are the same carbs found in lentils that may increase production of peptide hormone compounds that signal the brain to stop eating. In studies at the University of Surrey, England, after a breakfast and a lunch containing RS carbs, subjects ate about 10 percent fewer calories over the next twenty four hours compared with when they had similar meals with a placebo.
How to prepare and cook sweet potatoes?
Recent studies show excellent preservation of sweet potato anthocyanins with steaming, and several studies comparing boiling to roasting have shown better blood sugar effects with a lower GI value when boiling sweet potatoes. However, just two minutes of steaming have been shown to deactivate peroxidase enzymes that might otherwise be able to break down anthocyanins found in the sweet potato.
Choose sweet potatoes that are firm and do not have any cracks, bruises or soft spots. They do not like very cold temperatures so store in a cool, dark and well ventilated area for up to 10 days. Try to buy organic sweet potatoes so that you can eat the whole potato, flesh and skin. If this is not possible, you should peel before eating in case the skin has been treated.
As the flesh of sweet potatoes will darken upon contact with the air, you should cook them immediately after peeling and/or cutting them. If this is not possible, to prevent oxidation, keep them in a bowl covered completely with water until you are ready to cook them.