Potatoes vs sweet potatoes

Potatoes vs sweet potatoes might be one of the hottest debates in the nutrition world. Jokes aside, many of people wonder which is better. “Are potatoes paleo?” might be one of the most frequently asked questions in the past 10 years or so.

Potatoes and sweet potatoes – what are they?

Both potatoes and sweet potatoes are root vegetables. Despite their name, they are not botanically related. According to Merriam-Webster online:

Potato: “an erect South American herb (Solanum tuberosum) of the nightshade family widely cultivated for its edible starchy tuber” (1).

Sweet potato: “a tropical vine (Ipomoea batatas) of the morning-glory family that is often grown for its edible tuberous root or for its ornamental variously shaped green to purple leaves and usually white to pinkish funnel-shaped flowers with pink to purple centers
“also: the large thick sweet and nutritious tuberous root of the sweet potato that has beige, yellow, orange, red, or purple flesh and is cooked and eaten as a vegetable” (2)

Both potatoes and sweet potatoes can be used as the starchy component in meals. In fact, people following a strict paleo diet will often substitute sweet potato for potato in recipes. On the other hand, if you ever go to Peru, you might be served potatoes and sweet potatoes (and rice) in the same meal.

Nutrition in potatoes vs sweet potatoes

All the graphs below use data from AUSNUT (3).

Macronutrients

Potatoes and sweet potatoes are very low in fat and high in carbohydrates. Therefore, they are relatively low in energy (kilojoules). As shown in the graph below, regular potatoes are a bit higher in protein, but they are not to be considered a high protein food. Likewise, they are a bit lower in carbohydrates but are not to be considered a low carbohydrate food.

Speaking about carbohydrates, the amount of starch and sugar varies in potatoes vs sweet potatoes. White flesh sweet potatoes have the most starch, followed by white potatoes, followed by orange flesh sweet potatoes. Sugar is highest in orange sweet potatoes, followed by white sweet potatoes, followed by regular potatoes.

Glycaemic index

The glycaemic index (GI) measures how much a carbohydrate-containing food raises your blood sugar, relative to pure glucose. In general, white potatoes have a higher GI than sweet potatoes. What this means in practice is that people who have issues with blood sugar control (e.g. prediabetes, insulin resistance, diabetes, PCOS, etc.) should not consume large amounts of white potatoes. This doesn’t mean that those people can eat unlimited amounts of sweet potatoes – quantity matters too.

In addition, keep in mind that the GI is determined by measuring the blood sugar in a number of subjects after ingesting a set amount of food. Every person’s body will react slightly differently to the same food.

Micronutrients

Potatoes and sweet potatoes contain fibre, vitamin C and potassium, among other micronutrients. Orange flesh sweet potatoes also contain beta carotene, a precursor of vitamin A. See the table below for a comparison.

White potatoes that are cooked and cooled also contain resistant starch, a type of fibre that cannot be digested by us but serves as fuel for our gut bacteria.

Toxins

You might have heard of people who can’t eat nightshades because they cause inflammation in their bodies. This is due to an alkaloid present in this family of plants, which includes potatoes, eggplants, tomatoes, capsicum and chillies. If you suffer from inflammatory/autoimmune conditions you might be sensitive to white potatoes, but not sweet potatoes.

Culinary considerations

Even though potatoes and sweet potatoes are often used as substitutes in recipes, the truth is that they have different flavour and textures. If you do not like sweet ingredients in savoury dishes, sweet potatoes might not be something you’d like to add to your stews or casseroles. On the other hand, sweet potatoes can be a great way of adding sweetness to dishes like tagines and curries without having to add sugar or dried fruit, which is very high in sugar.

Texture-wise, as potatoes are starchier, they will be drier when cooked (fried, baked, mashed, etc.). This also means they will absorb more of the liquid/sauce they are served with.

Potatoes vs sweet potatoes – which one is better?

In summary, both potatoes and sweet potatoes have nutritional merit and might present some challenges for people who need to watch their carbohydrate intake, both in quantity and quality. When possible, it is best to rotate the vegetables you consume to get a variety of nutrients (and antinutrients/toxins).

Before you go

A bit of trivia

In Peru, where potatoes originated, there are 5000+ varieties of the tuber
In Spanish, regular potatoes are called “patata” (Spanish from Spain) or “papa” (everywhere else). “Papa” is also the word for “pope”.
Sweet potatoes have different names in Spanish, depending on the country. We call it “camote”, other names include “papa dulce”, “boniato” and “batata”

Recipes

Below are a few recipes using potatoes and sweet potatoes. Give them a try.

Reference

Merriam-Webster.com. potato: Merriam-Webster; 2019 [11 October 2019]. Available from: https://www.merriam-webster.com/dictionary/potato.
Merriam-Webster.com. sweet potato: Merriam-Webster; 2019 [11 October 2019]. Available from: https://www.merriam-webster.com/dictionary/sweet%20potato.
Food Standards Australia New Zealand (2014). AUSNUT 2011–13 – Australian Food Composition Database. Canberra: FSANZ. Available at www.foodstandards.gov.au

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Potatoes vs sweet potatoes

Potatoes and sweet potatoes – what are they?