The terms "sweet potato" and "yam" are often used interchangeably, leading to a lot of confusion.

While both are underground tubers, they are actually very different.

They belong to different plant families and are only distantly related.

So why all the confusion? This article explains the main differences between sweet potatoes and yams.

What are sweet potatoes?

They are believed to have originated in Central or South America, but North Carolina is currently the largest producer (1).

Surprisingly, sweet potatoes are only distantly related to potatoes.

Like a regular potato, the tuberous roots of the sweet potato plant are eaten as a vegetable. Their leaves and shoots are also sometimes eaten green.

However, sweet potatoes are a very distinctive tuber.

They are long and tapered with smooth yellow, orange, red, brown or mauve to beige skin. Depending on the type, the flesh can vary from white to orange and even purple.

There are two main types of sweet potatoes:

Dark-fleshed and orange-fleshed sweet potatoes

Compared to golden-skinned sweet potatoes, they are milder and sweeter, with darker, copper-brown skin and bright orange flesh. They tend to be chewy and moist and are commonly found in the United States.

Sweet potatoes with golden flesh and golden skin

This version is firmer with golden skin and pale yellow flesh. It tends to have a drier texture and is less sweet than dark-skinned sweet potatoes.
Regardless of the type, sweet potatoes are generally softer and moister than regular potatoes.

They are an extremely hardy vegetable. Their long lifespan allows them to be sold all year round. If stored properly in a cool, dry place, they can last up to 2-3 months.

You can buy them in different forms, most often whole or sometimes pre-peeled, cooked and sold canned or frozen.

Summary: Sweet potato is a starchy root vegetable native to Central or South America. There are two main varieties. They have a long shelf life and are generally softer and moister than regular potatoes.

What are yams?

Yams are also a tuber vegetable.

Their scientific name is Dioscorea, and they are native to Africa and Asia. They are now commonly found in the Caribbean and Latin America. More than 600 varieties of yams are known and 95% of them are still cultivated in Africa.

Compared to sweet potatoes, sweet potatoes can grow very large. The size can vary from that of a small potato to up to 1,5 meters (5 feet). Not to mention that they can weigh up to 60 kilograms (2).

Yams have distinct characteristics that set them apart from sweet potatoes, primarily their size and skin.

They have a cylindrical shape with a brown, rough, bark-like skin that is difficult to peel but softens after heating. Flesh color varies from white or yellow to purple or pink in mature yams.
Yams also have a unique taste. Compared to sweet potatoes, yams are less sweet and much more starchy and dry.

They also tend to have a good lifespan. However, some varieties store better than others.

In the United States, it can be difficult to find real yams. They are imported and rarely found in local grocery stores. Your best chance of finding them is in ethnic or international food stores.

Summary: True yams are an edible tuber native to Africa and Asia. There are over 600 varieties, which vary greatly in size. They are starrier and drier than sweet potatoes and are rarely found in local grocery stores.

Why do people confuse them?

So much confusion surrounds the terms sweet potatoes and yams.

The two names are used interchangeably and often mislabeled in supermarkets.

However, they are completely different vegetables.

A few reasons may explain how this confusion occurred.

African slaves who came to the United States called the local sweet potato “nyami,” which translates to “yam” in English. This is because it reminded them of real yams, a staple food they knew in Africa.

Additionally, the darker, orange-skinned variety of sweet potato was not introduced to the United States until several decades ago. To distinguish them from lighter-skinned sweet potatoes, growers labeled them "yams."

The term "yam" is now a marketing term allowing growers to distinguish the two types of sweet potatoes.

Most vegetables labeled as "yams" in American supermarkets are actually just a variety of sweet potatoes.

Summary: Confusion between sweet potatoes and yams arose when American growers began using the African term "nyami," which translates to "yam," to distinguish different varieties of sweet potatoes.

They are prepared and eaten differently

Sweet potatoes and yams are very versatile. They can be prepared by boiling, steaming, roasting or frying.

Sweet potatoes are more commonly found in American supermarkets. Therefore, as would be expected, it is used in a wider range of traditional Western dishes, both sweet and savory.

It is most often baked, mashed or roasted. It is commonly used to make sweet potato fries, an alternative to baked or mashed potatoes. It can also be pureed and used in soups and desserts.

On the Thanksgiving table, it is most often served as sweet potato casserole with marshmallows or sugar or made into sweet potato pie.

On the other hand, real yams are rarely found in Western supermarkets. However, they are a staple food in other countries, especially Africa.

Their long lifespan allows them to be a stable food source during times of crop failure (3).

In Africa, they are most often boiled, roasted or fried. Purple yams are most commonly found in Japan, Indonesia, Vietnam and the Philippines and are often used in desserts.

Yams can be purchased in different forms, including powdered, powdered or floured and as a supplement.

Yam flour is available in the West from grocers specializing in African products. It can be used to prepare a paste to serve with stews or stews. It can also be used in the same way as instant mashed potatoes.

Wild yam powder can be found in some health food and supplement stores under a variety of names. These include Mexican wild yam, colic root or Chinese yam.

Summary: Sweet potatoes and yams are boiled, roasted or fried. Sweet potatoes are used to make fries, pies, soups and casseroles. Yams are more often found in the West in the form of powder or dietary supplement.

Their nutrient content varies

A raw sweet potato contains water (77%), carbohydrates (20,1%), protein (1,6%), fiber (3%) and almost no fat (4).
In comparison, a raw yam contains water (70%), carbohydrates (24%), protein (1,5%), fiber (4%) and almost no fat (5).

A 3,5-ounce (100-gram) serving of baked sweet potato with the skin on contains (4):

• Calories: 90
• Carbohydrates: 20,7 grams
• Alimentary fiber: 3,3 grams
• Fat: 0,2 grams
• Protein: 2 grams
• Vitamin A: 384% HD
• Vitamin C: 33% HD
• Vitamin B1 (thiamine): 7% HD
• Vitamin B2 (riboflavin): 6% HD
• Vitamin B3 (niacin): 7% HD
• Vitamin B5 (pantothenic acid): 9% HD
• Vitamin B6 (pyridoxine): 14% HD
• The iron: 4% HD
• Magnesium: 7% HD
• Phosphorus: 5% HD
• Potassium: 14% HD
• Copper: 8% DV
• Manganese: 25% HD

A 3,5 ounce (100 grams) serving of boiled or baked yam contains (5):

• Calories: 116
• Carbohydrates: 27,5 grams
• Alimentary fiber: 3,9 grams
• Fat: 0,1 grams
• Protein: 1,5 grams
• Vitamin A: 2% HD
• Vitamin C: 20% HD
• Vitamin B1 (thiamine): 6% HD
• Vitamin B2 (riboflavin): 2% HD
• Vitamin B3 (niacin): 3% HD
• Vitamin B5 (pantothenic acid): 3% HD
• Vitamin B6 (pyridoxine): 11% HD
• The iron: 3%DV
• Magnesium: 5% HD
• Phosphorus: 5% HD
• Potassium: 19% HD
• Copper: 8% HD
• Manganese: 19% HD

Sweet potatoes tend to have slightly fewer calories per serving than yams. They also contain a little more vitamin C and more than triple the amount of beta-carotene, which converts to vitamin A in the body.

In fact, a 3,5-ounce (100-gram) serving of sweet potato will provide you with almost the entire recommended amount of vitamin A per day, which is important for vision and the immune system (4).

On the other hand, raw yams are slightly richer in potassium and manganese. These nutrients are important for bone health, proper heart function, growth and metabolism (6, 7).

Sweet potatoes and yams contain sufficient amounts of other micronutrients, such as B vitamins, which are vital for many bodily functions, including energy production and DNA creation.

It is also important to take into account each person's glycemic index (GI). The GI of a food gives an idea of ​​how slowly or quickly it affects your blood sugar.

GI is measured on a scale of 0 to 100. A food has a low GI if it causes a slow rise in blood sugar, whereas a high GI food causes a rapid rise in blood sugar.

Cooking and preparation methods can vary the GI of a food. For example, sweet potatoes have a medium to high GI, ranging from 44 to 96, while yams have a low to high GI, ranging from 35 to 77 (8).

Boiling, rather than baking, frying or roasting, is linked to a lower GI (9).

Summary: Sweet potatoes contain fewer calories and more beta-carotene and vitamin C than yams. Yams have slightly more potassium and manganese. They both contain decent amounts of B vitamins.

Their potential health benefits are different
Sweet potato is an excellent source of highly available beta-carotene, which has the ability to increase your vitamin A levels. This can be very important in developing countries where vitamin A deficiency is common (10).

Sweet potatoes are also rich in antioxidants, particularly carotenoids, which are believed to help protect against heart disease and reduce the risk of cancer (11, 12).

Certain types of sweet potatoes, especially purple varieties, are said to be highest in antioxidants – much higher than many other fruits and vegetables (13).

Additionally, some studies suggest that certain types of sweet potatoes may help improve blood sugar regulation and reduce “bad” LDL cholesterol in people with type 2 diabetes (14, 15, 16).

Meanwhile, the health benefits of yams have not been extensively studied.

There is little evidence that yam extract may be a useful remedy for some of the unpleasant symptoms of menopause.

A study of 22 postmenopausal women showed that high consumption of yams for 30 days improved hormone levels, reduced LDL cholesterol, and increased antioxidant levels (17).

It's important to remember that this was a small study and more evidence is needed to confirm these health benefits.

Summary: The high antioxidant content of sweet potatoes may protect against disease, improve blood sugar regulation, and reduce “bad” LDL cholesterol. Yams can help relieve menopausal symptoms.

Adverse reactions

Although sweet potatoes and yams are considered healthy and safe foods for most people, it may be wise to follow certain precautions.

For example, sweet potatoes have fairly high oxalate levels. These are natural substances that are generally harmless. However, when they build up in the body, they can cause problems for people at risk of kidney stones (18).

Care should also be taken when preparing yams.

Although sweet potatoes are safe to eat raw, some types of yams are not safe to eat until cooked.

The natural plant proteins found in yams can be toxic and cause illness if eaten raw. Peel and cook the yams well to remove all harmful substances (19).

Summary: Sweet potatoes contain oxalates which may increase the risk of kidney stones. Yams must be cooked well to remove natural toxic substances.

The final result

Sweet potatoes and yams are completely different vegetables.

However, they are both nutritious, tasty and versatile additions to the diet.

Sweet potatoes tend to be more readily available and are nutritionally superior to yams – although very slightly. If you prefer a softer, chewier, chewier texture, opt for sweet potato.

Yams have a starchier, drier texture, but might be harder to find.

You really can't go wrong with either one.