Blood sugar control.
Immune system strengthening.
Blood pressure regulation.
Growth and development.
It's pretty sweet we can gain all these benefits at once from ONE food alone: sweet potatoes!!! It can't be emphasized enough: these vegetables deliver some super sweet nutrition!
Sweet potatoes, Ipomoea batatas, are a member of the Morning Glory plant family (Convolvulaceae). The entire plant - roots, stems, and leaves - are all edible. Many of us are familiar mainly with the starchy root portion. You've most likely eaten them baked, roasted, mashed, or fried. The stems and leaves of the sweet potato plant can be eaten raw, sautéed, boiled or juiced, much like other leafy greens such as spinach, collards and kale.
Sweet potatoes are a staple food for many cultures. A single plant can produce between 40-50 roots, each ranging in weight from 3.5 ounces to 2.5 pounds. At minimum, that's nearly 9 pounds; at maximum: 125 pounds! Consider the sweet potato as one incredible, dependable approach against food insecurity, as it's been reported to support more people per hectare than any other food.
Sweet potato roots and leaves are each uniquely nutritious. The roots are a quality source of energy and micronutrients containing protein, starch, sugar, fiber, vitamins, minerals and bioactive compounds. The leaves are also an excellent source of micronutrients, though contain fewer macronutrients, and thus, fewer calories. These factors can prevent malnutrition, undernutrition, and even overnutrition.
Colorful Roots: Carotenoids & Anthocyanins
Sweet potato roots come in a variety of colors from white to pale yellow, from pink to orange, from red to deep purple.
Each color is telling of differences in nutrient composition. Generally, vegetables and fruits that are yellow, red, orange and green are promising sources of carotenoids. And it's usually a given that purple and blue plants contain anthocyanins.
Carotenoids are protective against oxidation. In the human body, they play critical roles in the skin's defense against the sun, they're involved in reducing diabetic retinopathy in those living with type 2 diabetes, and they protect our eyes from the harmful blue light emanating from our smartphones, laptops and televisions. It's well documented that carotenoids are protective against various forms of cancer, heart disease, night blindness, and macular degeneration.
Anthocyanins are also strong forces against oxidation. Protecting our body's cells from damage, anthocyanins set the stage for a reduction of inflammation and greater longevity. Anthocyanins defend us from carcinogens, heart disease and diabetes. They support our brain's memory and learning functions. These life-supporting compounds even play roles in efficient metabolism, maintaining the path towards a healthy weight.
White-fleshed sweet potatoes rank as the least nutritious variety of sweet potato.
Its white color indicates an absence of colorful carotenoids and anthocyanins. However, as is true for all sweet potatoes, the white variety also contains fiber and protein. These macronutrients help to slow digestion, giving us a feeling of fullness from a meal, as well as a more controlled rise of blood sugars. Fiber from sweet potato is an excellent tool in the management of heart and digestive health, due to its cholesterol-reducing function, support for our gut's good bacteria, and prevention of constipation. And despite the apparent lack of carotenoids and anthocyanins, white sweet potatoes do deliver some antioxidative activity. While they aren't the most nutritious variety of sweet potato, keep those few nutritional qualities in mind. Provided you have regular daily access to food, you're more likely to relieve hunger, stabilize your energy, and have a more comfortable bowel movement following a meal containing white sweet potato versus eating a single peanut butter and jelly made on white bread.
If you're looking for greater doses of carotenoids, and if the options are available to you, you can't go wrong picking out the more colorful types. When it comes to sweet potatoes, there's no guessing required!
Deeply colored orange-fleshed sweet potatoes are guaranteed to have an astounding quantity of carotenoids.
You can count on these roots to provide you with alpha-carotene, beta-cryptoxanthin, and the star of the carotenoids: beta-carotene. In fact, orange sweet potatoes are the NUMBER ONE source for beta-carotene!!!
The three carotenoids, alpha-carotene, beta-cryptoxanthin, and beta-carotene, are known as provitamins: they're converted to the active form of vitamin A in the body. Beta-carotene is most valuable because it yields twice as much active vitamin A than alpha-carotene and beta-cryptoxanthin.
Just 100 grams (3.5 ounces) of cooked orange sweet potato contains
11,500 micrograms (mcg) of beta-carotene!
By comparison, 100 grams each of orange carrots (as opposed to red, yellow, or purple), spinach, and butternut squash contain 8,330mcg, 6,290mcg, and 4,550mcg, respectively.
Altogether, the three provitamin A carotenoids found in orange sweet potatoes contribute 384% - yes, three hundred eighty-four percent - of the recommended daily intake of vitamin A! Quantities of this magnitude are what allow our blood levels of vitamin A to rise and keep our stores sufficiently stocked, eliminating the scares of deficiency.
Excited to take your carotenoid intake to the max? If you have access to sweet potato greens, you're in luck! These, too, are great sources of carotenoids, including smaller quantities of the aforementioned, as well as lutein and zeaxanthin. These latter two carotenoids don't have vitamin A forming capability. Instead, they are linked with prevention of age-related macular degeneration and cataracts, and they provide anti-aging and anti-cancer benefits by protecting our skin from the damaging effects of the sun.
Purple-fleshed sweet potatoes are another excellent option for nourishing your body well.
Their purple color is a tell-tale sign that anthocyanins are present! These phenolic compounds belonging to the flavonoid family are naturally purple, blue, red, and orange. Over 600 anthocyanins have been identified in nature, and of those 600, twenty-seven have been identified in the purple sweet potato.
Anthocyanins specific to the purple sweet potato have been shown to counter cancer cell proliferation. They can increase our ability to learn and retain info for longer. These compounds are supportive of healthier blood sugar levels, beneficial for both those living with diabetes and those making efforts to prevent it. Purple sweet potato anthocyanins may lower the health risks posed by heavy metals and free radicals. And due to their anti-inflammatory properties, they're our ally in the fight against high blood pressure and heart disease.
No matter what color the sweet potato root is, consuming the entire plant - roots to leaves - is most advantageous for our health. Just as we can boost our carotenoid consumption by pairing the orange roots with stems and leaves, pairing purple sweet potatoes with the plant's stems and leaves is also great for maximizing our anthocyanin intake. But don't fret if only the roots are accessible to you. You'll still gain plenty of carotenoids from the orange, and plenty of anthocyanins from the purple.
Vitamin A Deficiency
As previously noted, just a 3.5 ounce portion of orange sweet potato can provide almost four times of your daily need for vitamin A. The high concentration of carotenoids in food do not risk vitamin A toxicity, like high doses of vitamin A supplementation can. High concentrations of dietary carotenoids can cause a harmless yellowing of the skin called, carotenodermia or carotenemia. The condition will disappear with decreased intake of carotenoids. Altogether, orange sweet potatoes are an excellent method to support sufficient blood levels of vitamin A and prevent deficiency.
Deficiency of vitamin A is most common in developing countries, especially where white-fleshed sweet potatoes are the predominant cultivar. In these parts of our world, vitamin A deficiency is most significantly impacting millions of young children and women.
Vitamin A, which is best absorbed in the body when in the presence of fat, is in high demand throughout pregnancy, lactation and childhood. It's a critical component in growth and development. Deficiency can lead to vision impairments including night blindness and xerophthalmia (a dry thickened lusterless condition of the eyeball); increased risk of infection and weakened immune system. Ultimately, a severe vitamin A deficiency greatly increases the the risk for mortality.
This public health problem is recognized, and efforts such as supplementation, and replacing white sweet potatoes with orange cultivars are methods that have been, and are, being promoted in these parts of our world.
Sweet Potatoes Are Not Potatoes or Yams
Sweet potatoes are not true potatoes - of course, it's obvious why you may have thought so. But the greatest confusion of all is whether or not they're yams, and the answer is: no. Let's lay these conundrums to rest!
All three belong to different botanical families. As you now know, the Ipomoea batatas belongs to the Convolvulaceae, or Morning Glory family, and is considered a tuberous root consisting of many nutrients. The root is starchy and contains natural sugars that produce a palatable, sweet taste. The sweet potato has smooth skin and is oblong in shape, often with tapered ends.
Potatoes, including Russets, Fingerling, Yukon Gold, Purple Majesty and Red Gold, all belong to the nightshade family, or Solanum tuberosum. The starchy vegetable is considered a tuber and contains very few natural sugars. Potatoes are a good source of fiber, vitamins and minerals including vitamin C and potassium.
The yam, also a starchy vegetable, belongs to the Dioscoreaceae family. The edible tuber is a rhizome - or, a thickened stem - that grows horizontally below ground. It's more cylindrical in shape and has bark-like skin. Yams are much lower in vitamin A, providing only 2% of the recommended daily intake from a 100 gram portion. They are great sources of fiber, vitamin C and potassium. However, unlike sweet potatoes they contain very little natural sugars, often leading to a starchier, and sometimes bitter taste.
Selecting and Storing Sweet Potato Roots
Choose sweet potato roots that are firm with a smooth skin. A sweet potato root that can bend, appears withered, or is covered in many holes is indicative of a long storage time. While some length of storage is beneficial in regards to the development of sugar - leading to a tastier sweet potato - longer storage periods begin to negatively impact total nutrient quantity, including antioxidant activity. Avoid storing your sweet potatoes in the fridge or in direct sunlight. Instead, store them in a cool, dry place - such as the pantry or cupboard - up to a month.
Bovell-Benjamin A. C. (2007). Sweet potato: a review of its past, present, and future role in human nutrition. Advances in food and nutrition research, 52, 1–59. https://doi.org/10.1016/S1043-4526(06)52001-7
Britannica, T. Editors of Encyclopaedia (2019, March 8). Convolvulaceae. Encyclopedia Britannica. https://www.britannica.com/plant/Convolvulaceae
Britannica, T. Editors of Encyclopaedia (2021, May 30). Potato. Encyclopedia Britannica. https://www.britannica.com/plant/potato
Britannica, T. Editors of Encyclopaedia (2020, November 25). Sweet potato. Encyclopedia Britannica. https://www.britannica.com/plant/sweet-potato
Britannica, T. Editors of Encyclopaedia (2020, November 25). Yam. Encyclopedia Britannica. https://www.britannica.com/plant/yam
Merriam-Webster Dictionary. (2021, October). Xerophthalmia. https://www.merriam-webster.com/dictionary/xerophthalmia
Mohanraj, R., & Sivasankar, S. (2014). Sweet potato (Ipomoea batatas [L.] Lam)--a valuable medicinal food: a review. Journal of medicinal food, 17(7), 733–741. https://doi.org/10.1089/jmf.2013.2818
National Institutes of Health. (2021, March 26). Vitamin A: Fact Sheet for Health Professionals. Office of Dietary Supplements.
Neela, S., & Fanta, S. W. (2019). Review on nutritional composition of orange-fleshed sweet potato and its role in management of vitamin A deficiency. Food science & nutrition, 7(6), 1920–1945. https://doi.org/10.1002/fsn3.1063
Nutrition Data: Know what you eat. (2018, May 25). Potato, baked, flesh and skin, without salt Nutrition Facts & Calories. https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2770/2
Nutrition Data: Know what you eat. (2018, May 25). Sweet potato, cooked, baked in skin, without salt [Sweetpotato] Nutrition Facts & Calories. https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2667/2#ixzz79evKDOuJ
Nutrition Data: Know what you eat. (2018, May 25). Sweet potato leaves, cooked, steamed, without salt [Sweetpotato leaves] Nutrition Facts & Calories.
Nutrition Data: Know what you eat. (2018, May 25). Yam, cooked, boiled, drained, or baked, with salt, Nutrition Facts & Calories. https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2969/2
Rose, I.M., & Vasanthakaalam, H. (2011). Comparison of the Nutrient composition of four sweet potato varieties cultivated in Rwanda. American Journal of Food and Nutrition, 1(1): 34-38. doi:10.5251/ajfn.2011.1.1.34.38
Unicef. (2021, October). Vitamin A Deficiency. https://data.unicef.org/topic/nutrition/vitamin-a-deficiency/
Wang, S., Nie, S., & Zhu, F. (2016). Chemical constituents and health effects of sweet potato. Food research international (Ottawa, Ont.), 89(Pt 1), 90–116. https://doi.org/10.1016/j.foodres.2016.08.032
Yousuf, B., Gul, K., Wani, A. A., & Singh, P. (2016). Health Benefits of Anthocyanins and Their Encapsulation for Potential Use in Food Systems: A Review. Critical reviews in food science and nutrition, 56(13), 2223–2230. https://doi.org/10.1080/10408398.2013.805316