Sweet Potato

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By Medifit Education






Cultivation of sweet potatoes, which are native to Peru, dates back to 750 BCE. Discovered by Columbus, sweet potatoes, often (wrongly) called yams, belong to the Convolvulaceae, or morning glory plant family. Yams (from the African word “nyami”), which are from the Dioscoreae family, have only one embryonic seed leaf, while sweet potatoes have two. Another note for consumers: yams are usually more moist.

There are about 400 varieties of sweet potato, some more rare than others, differentiated by their skin and flesh color, ranging from cream, yellow, and orange to pink or purple. Oxidation turns them dark in spots after peeling, so it’s best to bake or steam immediately, or place in water until you do.

Baked sweet potatoes are a lovely alternative to plain white, especially with butter, salt, and pepper. Sweet potato chips and fries (cooked in coconut oil) are tasty snacks. Boiling isn’t recommended because of potentially lost nutrients.

It’s good to know that the health benefits of sweet potatoes may even surpass their reputation as a holiday favorite, having unique attributes not seen in other plant-based foods.


02 sweet potato



Sweet potatoes were transported to Spain, probably by Columbus, in about 1500. Several varieties, including purple and red, were cultivated there by the mid-16th century. Other Spanish explorers carried the orange and purple-hued tubers to the Philippines and East Indies, and from there cultivation spread to India, China, and beyond, via Portuguese voyagers.

In 1740s, “sweet” potatoes became known as such in the American colonies to distinguish them from white “Irish” potatoes.



Don’t just serve deliciously honeyed or savory sweet potatoes on holidays; enjoy them regularly in a plethora of ways – sautéed, baked, steamed, or fried – because they’re good for you! Antioxidants take the bite out of free radicals roaming throughout your body looking for a place to cause damage, but that’s just one of the tremendous health benefits you get from sweet potatoes. Anthocyanidins, which give them deep pigments such as orange and purple, contain flavonoid and antioxidant clotting, wound-healing, and heavy metal cleansing properties.

Sweet potatoes come with super strong beta-carotenes, along with copper/zinc superoxide dismutase and catalase, adiponectin for balancing your insulin, impressive doses of vitamin A, plus good levels of vitamin C and vitamin B6. Studies have proven both orange and purple sweet potatoes to be cancer fighters, but purple sweet potatoes include cyanidins and peonidins for extra protection.

Including three to five grams of (good) fat with every meal significantly increases your beta-carotene uptake from sweet potatoes, easily done by using one tablespoon of extra virgin olive oil.



Sweet potatoes are a Native American plant that was the main source of nourishment for early homesteaders and for soldiers during the Revolutionary War. These tuberous roots are among the most nutritious foods in the vegetable kingdom. They are packed with calcium, potassium, and vitamins A and C. This is why one colonial physician called them the “vegetable indispensable.” Sweet potatoes are often confused with yams, but yams are large, starchy roots grown in Africa and Asia. Yams can grow up to 100 pounds and are rarely available in American supermarkets. Nutritionally, sweet potatoes greatly outweigh yams. Because of the common use of the term “yam,” it is acceptable to use this term when referring to sweet potatoes. Sweet potatoes contain an enzyme that converts most of its starches into sugars as the potato matures. This sweetness continues to increase during storage and when they are cooked.





The deep orange color is more than just different than white potatoes; it’s one of the indications of beta-carotene presence, shown by numerous studies to be especially rich in sweet potatoes. The vitamin A per serving even rivals that of green leafy vegetables (yams only have 3%!), providing 769% of the daily value per serving. In fact, the only food that has more vitamin A is three ounces of beef liver! The 65% daily value of vitamin C and 29% DV of vitamin B6 isn’t too bad, either.

Two key antioxidant enzymes in sweet potatoes are copper/zinc superoxide dismutase and catalase. One study showed purple sweet potatoes to have more than three times the antioxidant activity than that of one type of blueberry.

Especially in light of their high sugar content, a surprising fact about sweet potatoes is their ability to help regulate blood sugar, even in type 2 diabetes patients. Research has verified that sweet potato extract can increase blood levels of adiponectin, a protein hormone produced by your fat cells, to regulate the way your body metabolize insulin, and even lower insulin levels when needed.

However, make sure you consume sweet potatoes in moderation, as some varieties are high in fructose. In fact, the American sweet potato has been literally bred for sweetness, with 6.5 grams of sugar per 100 grams.



  1. They are high in vitamin B6. Vitamin B6 helps reduce the chemical homocysteine in our bodies. Homocysteine has been linked with degenerative diseases, including heart attacks.


  1. They are a good source of vitamin C. While most people know that vitamin C is important to help ward off cold and flu viruses, few people are aware that this crucial vitamin plays an important role in bone and tooth formation, digestion, and blood cell formation. It helps accelerate wound healing, produces collagen which helps maintain skin’s youthful elasticity, and is essen­tial to helping us cope with stress. It even appears to help protect our body against toxins that may be linked to cancer.


  1. They contain Vitamin D. which is critical for immune system and overall health at this time of year. Both a vitamin and a hormone, vitamin D is primarily made in our bodies as a result of getting adequate sunlight. You may have heard about seasonal affective disorder (or SAD, as it is also called), which is linked to inadequate sunlight and therefore a vitamin D deficiency. Vitamin D plays an important role in our energy levels, moods, and helps to build healthy bones, heart, nerves, skin, and teeth, and it supports the thyroid gland.


  1. Sweet potatoes contain iron. Most people are aware that we need the mineral iron to have adequate energy, but iron plays other important roles in our body, including red and white blood cell production, resistance to stress, proper im­mune functioning, and the metabolizing of protein, among other things.


  1. Sweet potatoes are a good source of mag­nesium, which is the relaxation and anti-stress mineral. Magnesium is necessary for healthy artery, blood, bone, heart, muscle, and nerve function, yet experts estimate that approximately 80 percent of the popula­tion in North America may be deficient in this important mineral.


  1. They are a source of potassium, one of the important electrolytes that help regulate heartbeat and nerve signals. Like the other electrolytes, potassium performs many essential functions, some of which include relaxing muscle contractions, reducing swelling, and protecting and controlling the activity of the kidneys.


  1. Sweet potatoes are naturally sweet-tasting but their natural sugars are slowly released into the bloodstream, helping to ensure a balanced and regular source of energy, without the blood sugar spikes linked to fatigue and weight gain.


  1. Their rich orange color indicates that they are high in carotenoids like beta carotene and other carotenoids, which is the precursor to vitamin A in your body. Carotenoids help strengthen our eyesight and boost our immunity to disease, they are powerful antioxidants that help ward off cancer and protect against the effects of aging. Studies at Harvard University of more than 124,000 people showed a 32 percent reduction in risk of lung cancer in people who consumed a variety of carotenoid-rich foods as part of their regular diet. Another study of women who had completed treatment for early stage breast cancer conducted by researchers at Women’s Healthy Eating and Living (WHEL) found that women with the highest blood concentrations of carotenoids had the least likelihood of cancer recurrence.


  1. There are versatile. Try them roasted, puréed, steamed, baked, or grilled. You can add them to soups and stews, or grill and place on top of leafy greens for a delicious salad. I enjoy grilling them with onions and red peppers for amazing sandwich or wrap ingredients. Puree them and add to smoothies and baked goods.



The inspiration for this post comes from a reader’s comment about wanting more information about the origin of “candied” yams.

Whether you boil and drizzle with molasses or mash and top with marshmallows, sweet potatoes* have become a staple at Thanksgiving tables.

Did you know that sweet potatoes were cultivated and consumed before the white (Irish) potato?

The earliest cultivation records of the sweet potato date to 750 BCE in Peru, although archeological evidence shows culivation of the sweet potato might have begun around 2500-1850 BCE.  By the time Christopher Columbus arrived in the ‘New World’ in the late 15th century, sweet potatoes were well established as food plants in South and Central America.

Columbus brought sweet potatoes back to Spain, introducing them to the taste buds and gardens of Europe. Europeans referred to the sweet potato as the potato, which often leads to confusion when searching for old sweet potato recipes. It wasn’t until after the 1740’s that the term sweet potato began to be used by American colonists to distinguish it from the white (Irish) potato.

England’s John Gerard wrote about the potato (sweet potato) in his 1597 Herball or Generall Historie of Plantes. Along with a description of the plant, he also describes how it is eaten- roasted and infused with wine, boiled with prunes, or roasted with oil, vinegar, and salt. He also suggests that the sweet potato “comforts, strengthens, and nourishes the body,” as well as “procuring bodily lust.” This aphrodisiac quality could be the reason for its popularity in the upper classes of 16th century England.  It is suggested that Henry VIII consumed massive amounts of sweet potatoes, especially spiced sweet potato pie and Shakespeare’s Falstaff exclaims in the Merry of Wives of Windsor (1602) “Let the sky rain potatoes. Let it thunder to the tune of ‘Greensleeves,’ hail kissing-comfits and snow eryngoes!”  A recipe  in John Murrell’s 1615 A New Booke of Cookery published in London A recipe in Thomas Dawson’s Book of Cookerie (1620, 1629) includes “A tarte to cause courage either in a man or woman” that uses potato [sweet potato].



Without a doubt, by 1880 Americans were enjoying some sort of variation of candied sweet potatoes. American cookbooks, such as the widely published 1893 Boston Cooking School Cookbook by Fannie Farmer featured a recipe for glazed sweet potatoes. Likewise, in 1896 Texas Farm and Ranch published Sweet Potato Culture for Profit: A Full Account of the Origin,History and Botanical Characteristics of Sweet Potato , which included a recipe for glazed sweet potatoes.

Around the same time, George Washington Carver compiled more than a hundred recipes for the vegetable. Carver’s recipes no. 9 and 10 discuss two different ways to make glacé sweet potatoes (glacé often refers to something that is sugared or candied). By the 1910’s candied sweet potato recipes were wide-ranging in the United States, appearing in Martha McCulloch-Williams 1919 Dishes from the Old South and Florence Greenbaum’s 1919 International Jewish Cookbook.




Neffsville, Pennsylvania. Mrs. Earle Landis taking Thanksgiving pies from the oven (FSA/OWI, 1942).

Early sweet potato pudding recipes, such as the one found in the first American cookbook,American Cookery(1789 1796)  by Amelia Simmons features a recipe for potato pudding** that is similar to our contemporary recipe for candied sweet potato with marshmallows. It includes mashed sweet potatoes, milk, nutmeg, and egg whites. Eliza Leslie’s 1840 Directions for Cookery also gives instructions for a sweet potato pudding, calling for mashed sweet potatoes and milk, topped with egg whites, and baked in the oven.

One of the earliest published recipes that uses marshmallows was in a 1919 booklet from the Barrett Company on Sweet Potato and Yams, which suggests adding marshmallows to candied yams.**(Nov. 2012 Update- Saveur Magazine, Oct. 2011,  writes “ In 1917, the marketers of Angelus Marshmallows hired Janet McKenzie Hill, founder of the Boston Cooking School Magazine, to develop recipes for a booklet designed to encourage home cooks to embrace the candy as an everyday ingredient.” This booklet  contained “the first documented appearance of mashed sweet potatoes baked with a marshmallow topping.”)  A decade later, Ida C. Bailey Allen’s Vital Vegetables (1928) gives readers a browned sweet potatoes with marshmallows recipe.

Tracing the history of candied sweet potato/yam recipes was a challenge. It seems that this dish may have its origins in 16th century Europe. However, the predominance of references to candied (glazed, glacé) sweet potato recipes from 18th and 19th century cookbooks suggest that this delicacy stems from American recipes.

Over the past two years I have been involved with more  in-depth research about the sweet potato. Based on this research the cultivated dates of the sweet potato in Peru should be 2500-1850 BCE due to archaeological evidence that has, more or less, been accepted by the community.  I am also asked for assistance in researching the history of the sweet potato.



Sweet potato is from the Morningglory (Convolvulaceae) plant family. Its correct spelling is “sweetpotato” one word. As a crop it is totally different from a potato (Solanum tuberosum) and from a yam – “nyami” (Dioscoreaceae).

After much discussion and consideration, I decided to use the generally accepted two-word spelling throughout this site.

Sweet potato has secondary centers of genetic diversity. These are geographical areas where the crop evolved separately from its American ancestors.

In Papua New Guinea and in other parts of Asia, many types of sweet potato can be found that are genetically distinct from those found in the Americas.

It’s unclear as to how sweet potato got to the southwest Pacific. Some researchers believe European explorers took them there; others believe sweet potato was moved from island to island across the Pacific by indigenous people.


By Medifit Education