Purple yams and purple sweet potatoes are often mistaken for one another and are mistakenly referred to as “yams.” There are similarities and differences leading many people to ask, what’s the difference between a purple sweet potato and purple yam?
Purple sweet potatoes and purple yams are distinct types of vegetables. Purple sweet potatoes grow underground as tubers while purple yams grow underground also from a vine plant above ground. Purple yams taste sweeter than purple sweet potatoes and are more difficult to find in the United States.
This article includes a side-by-side nutrient comparison. In addition, I’ll discuss their tastes, textures, culinary differences, costs and whether one can substitute for the other. Then I’ll examine their health benefits and if one is easy to store than the other.
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Is Purple Sweet Potato and Purple Yam The Same?
Purple sweet potatoes and purple yams are not the same. The narrower purple yams have a brown-reddish colored skin with a light purple flesh. Purple sweet potatoes have a beige outer skin with a blue-purple flesh. Purple yams are a species of yam native to South East Asia while purple sweet potatoes are native to Polynesia and South America.
First, let’s take a look at each one individually.
Also known as ube, the purple yam is a distinct species of yam native to South East Asia. Yams grow as a tuber underground. Above ground the vined plant can grow rapidly and long. The purple yam has a sweet and nutty flavor with hints of vanilla and pistachio.
Ube is high in vitamin C, antioxidants, and resistant starch. Yams, in general, are a good source of beta carotene, although the purple variants contain less than orange variants. The purple yam is also relatively high in anthocyanin, an antioxidant that gives it its purple color.
We’ll discuss nutritional details and taste comparisons more in-depth later in this article.
Purple Sweet Potatoes
There are many different varieties of sweet potato with purple color. Depending on the region you live in, the ones you find at your local store could be from one out of a dozen different varieties. The species most common in the United States is Ipomoea batatas, which grows in many different colors.
The purple sweet potato is native to Polynesia and South America and is a good source of beta carotene like the purple yam. Also, like the purple yam, the purple coloration comes from the anthocyanin content.
Purple sweet potatoes are high in oligosaccharides, which are prebiotics promoting healthy gut flora.
There are two main common variations of purple sweet potato. These include:
- Okinawa Sweet Potatoes: Okinawa’s originated in Central and South America but are locally grown in Hawaii. They have white skin with deep purple flesh. Although they have a bluish-purple color, their texture is dry and starchy with a mildly sweet and bitter aftertaste.
- Stokes Sweet Potatoes: Stokes was initially native to North Carolina but is grown commercially in Central California. Stokes has purple skin and flesh, a moist and starchy texture and a mildly sweet floral taste. Available year-round, these sweet potatoes have purple-tinted skin with a deep purple flesh that intensifies when cooked.
Purple yam or Dioscorea alata, grows underground like sweet potatoes. They are considered an invasive species in the southern US.
Purple yams contain the toxin dioscorine and must be thoroughly cooked to make them suitable for human consumption. Dioscorine, a neurotoxin, can cause nausea, dizziness, and vomiting in small doses, and convulsions or other serious side effects in large quantities.
Notably, many cultivars of the purple yam are sterile, so wild dispersal of the fruit is uncommon. Accordingly, purple yams throughout South East Asia are indicators of ancient human migration used by evolutionary biologists and anthropologists.
On the other hand, purple sweet potatoes come in many different varieties depending on the region in which they are found. Some varieties are cultivated extensively in the US, whereas others are native to South East Asia, like the purple yam.
Like the purple yam, the purple sweet potato gets its bright coloration from the antioxidant anthocyanin. This is the same chemical responsible for the red/purple coloration in red wine and red cabbage.
Purple Sweet Potato vs Purple Yam: Taste and Texture
Since they are grown differently and come from different areas of the world, one would think they taste different. Let’s examine the taste and texture of a purple sweet potato and purple yam.
Purple sweet potatoes have a rich taste, almost wine-like flavor with a creamy texture. Purple yams are sweeter and nuttier than purple sweet potatoes. Purple sweet potatoes and purple yams are starchy and dry.
What does a purple yam taste like? The purple yam has a sweet and nutty flavor with hints of vanilla and pistachio. The texture is soft like a potato when cooked.
What does purple sweet potatoes taste like? Purple sweet potatoes have a rich taste with a wine-like flavor. The texture is dry but slightly creamy.
Purple Sweet Potatoes and Purple Yams Substitutions
Purple yams may be difficult to find in the supermarket. Therefore, they may be unavailable for a recipe. For this reason, many people ask, can I substitute purple sweet potato for purple yams or Ube?
Purple sweet potatoes and purple yams can substitute for each other due to their similar tastes and textures. They can both be boiled, steamed, baked, fried, shredded, roasted or made into chips. Substitute purple sweet potatoes or purple yams each with equal quantities.
How to Cook Purple Yams
Purple yams can be cooked similar to the way sweet potatoes are cooked and used in the same traditional potato recipes.
In the Philippines, purple yams are used to make purple jam by blending it with evaporated milk, coconut milk, condensed milk and sugar. The mixture is simmered for about 45 minutes. The mixture is added to the following:
- Ice cream
- Anything to add a bright purple color.
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How to Cook Purple Sweet Potatoes
Purple sweet potatoes can be cooked similar to regular sweet potatoes or white potatoes. They can be:
Purple sweet potatoes require a longer cooking time than orange sweet potatoes.
Find out how regular sweet potatoes nutrients compared to regular yams in my article, Sweet Potato vs Yam Nutrition and Benefit Differences.
Purple Sweet Potatoes and Purple Yam Costs
With the rising prices of just about everything lately, the cost of something certainly matters to most people. The price may sway your decision about which food to use. Therefore, which costs more, purple sweet potatoes or purple yams?
Purple yams cost more than purple sweet potatoes. The average price for sweet potatoes is $0.99 per pound. The average price for purple yams is $13.73 per pound.
Depending on where you live, it may be easier to find purple sweet potatoes than purple yams.
In the United States, it is rare to find fresh purple yams. Purple sweet potatoes, however, are readily available and cheap to acquire. In South East Asia, it may be easier and cheaper to get purple yams.
I conducted an extensive search for purple yams and purple sweet potatoes online. I was only able to find purple yams on Amazon. Purple jams made with purple yams were more available, and I found those in most stores.
I checked Shoprite supermarket for the prices of purple sweet potatoes and purple yams:
- Purple sweet potatoes
- $2.99 per pound
I also checked Walmart and only found regular sweet potato prices.
I then checked a specialty store (Friedas) and found the following purple sweet potato price:
- Purple sweet potatoes
- $4.00 per pound
I then checked Amazon and found the following price for purple yams:
- Purple yams
- $13.73 per pound
How To Store Purple Yams and Purple Sweet Potatoes
Whichever you choose or have on hand, properly storing them is important. How you store them can affect their quality and how long they last before going bad. Therefore, how do you store purple yams and purple sweet potatoes?
Store purple yams and purple sweet potatoes in a dark, cool place away from heat and do not store either in the refrigerator. A humid basement or root cellar is the best area. They should be kept in a burlap bag or ventilated container and stored between 40°F and 60°F.
Storing purple yams or sweet potatoes in a refrigerator can make the center hard and change the cell structure. This can diminish the flavor. If you don’t have a cool basement, store them in a ventilated place, away from heat and light.
Don’t wash the purple yams or purple sweet potatoes before storing them. The moisture will promote the growth of bacteria and fungus 1.
Humid storage locations are best because potatoes and yams are 80% water and can dry out if stored in a drier place. Commercial potato storage facilities are set at 90 to 95% relative humidity 2.
Purple Sweet Potatoes and Purple Yams Glycemic Index
Knowing the glycemic index of purple sweet potatoes and purple yams is important especially if blood sugar levels are a concern. Avoiding blood sugar spikes is an important thing people should be aware of, diabetic or not.
The Glycemic Index (GI) is a scale measuring how fast a particular food raises the blood sugar in the blood 3. Blood sugar spikes can lead to health complications with the kidneys, nerves, heart and eyes 4.
Foods on the GI scale are categorized as:
- Low-GI foods: 55 or under
- Medium-GI foods: 56-69
- High-GI foods: 70 or over
How blood sugars levels are affected:
- Foods with a glycemic index 70 or more cause a quicker spike in blood sugar levels.
- Foods with a glycemic index 56 to 69 cause a moderate spike in blood sugar levels.
- Foods with a glycemic index 55 or less cause a slow spike in blood sugar levels.
Now we know what GI is, and how it affects blood sugar, let’s answer, does purple sweet potatoes or purple yams have a higher GI?
Purple sweet potatoes and purple yams have a moderate glycemic index depending on the cooking method used.
Find out how turnips compared to potatoes in my article, Turnip vs. Potato: What’s The Difference? Let’s Compare.
Purple Sweet Potatoes and Purple Yams Nutrients
Any meaningful discussion about health benefits must start with reviewing nutritional information. Therefore, let’s quickly look at the nutrient content of purple yams and purple sweet potatoes.
Here’s a table of the nutritional contents of a 100-gram (3.5 ounce) serving of raw purple sweet potato and purple yam.
|Purple Sweet Potato (100 g)||Purple Yam (100 g)|
|Protein||1.54 g||1.00 g|
|Carbohydrates||20.0 g||27.0 g|
|Fiber||3.1 g||4.0 g|
|Fat||0.1 g||0.1 g|
|Sugar||3.85 g||0 g|
|Vitamin C||10.9 mg||12.0 mg|
|Potassium||337 mg||611 mg|
|Iron||0.62 mg||0.36 mg|
|Calcium||30 mg||20 mg|
Purple sweet potatoes contain fewer calories and carbohydrates than purple yams. Purple sweet potatoes provide more protein, iron and calcium. Purple yams provide more fiber, vitamin C and potassium than purple sweet potatoes.
Both have similar nutrients and are considered healthy. There’s not much of a difference between the two and most people can’t go wrong choosing either one.
Find out how white sweet potatoes compared to sweet potatoes in my article, White Sweet Potato vs. Sweet Potato: What’s The Difference?
Health Benefits of Purple Sweet Potatoes and Purple Yams
Yams, in general, are a good source of beta carotene, although the purple variants contain less than orange variants. The purple yam is also relatively high in anthocyanin, an antioxidant that gives it its purple color.
Purple sweet potatoes are rich in anthocyanins. As mentioned earlier, anthocyanins are the pigments that give red, purple, and blue fruits, plants and vegetables their rich coloring and provide anti-inflammatory benefits.
The Immune System
According to Harvard University, vitamin A is a great source to stimulate healthy white blood cells 8. These cells have the responsibility of keeping the immune system as healthy as possible to fight viruses and illnesses effectively.
The purple sweet potato provides 10.9 mg of vitamin C compared to 12.0 mg for purple yams. The body can’t make vitamin C, so it must come from the foods ate every day. Vitamin C has been shown in studies to help with the growth and repair of tissues throughout the body 9.
Vitamin C helps heal and repair wounds, maintain healthy bones, skin and cartilage. Vitamin C acts as an antioxidant and fights free radicals which damage the cells. Helping to prevent cell damage can help with the following:
- Certain diseases like cancer.
- Heart disease.
- Promote healthy aging.
Heart Health and Blood Pressure
Purple yams and purple sweet potatoes benefit the heart in several ways. One reason is due to the vitamin C. This vitamin helps lower blood pressure in individuals with elevated blood pressure levels and those without 10.
Vitamin C also helps check several risk factors of heart disease, including the following:
- High blood pressure.
- High levels of “bad” cholesterol.
- Low “good” cholesterol levels.
By reducing these risk factors, it helps reduce your chances of developing heart disease.
The effectiveness of Vitamin C in reducing the risk of heart disease is well documented in various studies. For instance, a review of 9 scientific studies with almost 300,000 participants established maintaining a daily consumption of at least 700 mg of vitamin C for ten years lowers the risk of heart disease by 25% 11.
Purple yams and purple sweet potatoes contain the following nutrients beneficial for blood pressure:
- Vitamin C
Let’s take a look at each one of these minerals and how they benefit blood pressure. Vitamin C was already discussed earlier.
Magnesium helps keep blood pressure levels stable and balanced. Recent scientific research examined previous studies and concluded magnesium supplementation decreased systolic and diastolic blood pressure 12.
Magnesium helps control the following:
- Blood pressure
- Blood sugar
- Nerve function
One reason many people supplement with magnesium in the evening is because it helps calm the whole body including blood vessels.
In the heart and muscles, magnesium competes with calcium to help the muscles relax after contracting. When the body is low in magnesium, calcium can over stimulate the heart muscle’s cells causing a rapid or irregular heartbeat 13.
Purple yams provide 611 mg of potassium and purple sweet potatoes 337 mg. Potassium helps the body get rid of excess sodium reducing fluid build-up. These help keep systolic and diastolic blood pressure lower 14.
According to Harvard Health, a number of studies have shown a connection between low potassium levels and high blood pressure 15.
The more potassium, the more sodium your body will lose. Consuming too much sodium or not enough potassium throws off the delicate balance the kidneys need to remove the excess water 16.
Purple yams provide 20 grams of calcium and purple sweet potatoes 30 mg. Calcium is important for the heart and blood pressure. Harvard Health reports calcium helps maintain blood pressure by helping in the controlling of the relaxing and tightening of blood vessels 17.
Calcium also helps the following:
- Helps nerve function.
- Helps muscles function properly.
- Build and maintain strong bones.
Digestion and Gut Health
Purple sweet potatoes and purple yams both contain soluble and insoluble fiber. Fiber remains in the digestive tract and provides gut related health benefits. Fiber rich diets have been linked to regular bowel movements and a lower risk of colon cancer 18.
If you’re interested about how sweet potatoes held up against pumpkin for health and nutrition, check out my article, Pumpkin vs Sweet Potato: A Complete Comparison.
Wrapping Up Purple Sweet Potatoes and Yams
Both purple yams and purple sweet potatoes provide a decent nutritional profile while bringing loads of color and flavor to any dish.
Either one is a good option, and they can be easily substituted for one another in many dishes without sacrificing flavor or nutrition.
Read Next – More Potato vs Food Articles!
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