Sweet potato

Sweet potato is the sweetish storage root of a bindweed – not a potato. Roast, boil, mash or bake it as wedges for curries, soups and bowls. Store at 12–15 °C.

Botanically, the sweet potato isn't a potato, but in the kitchen it's used in much the same way. In this guide you'll find out where it stands on nutrients, fibre and glycaemic index – without exaggeration and with a focus on everyday cooking.

What is a sweet potato?

The sweet potato (Ipomoea batatas) belongs to the bindweed family, so it isn't related to the ordinary potato (Solanum tuberosum) from the nightshade family. What you eat is the thickened storage root. It originally comes from Central and South America and is now grown in many warm regions around the world.

Depending on the variety, the flesh is white, yellow, orange or purple. The colour matters nutritionally: orange varieties contain a lot of beta-carotene, purple ones contain anthocyanins, which are also found in blueberries. In Germany you can buy sweet potatoes all year round, mostly imported; locally grown ones are more seasonal and usually available from late summer to autumn.

Nutrition per 100 g

The values vary a little depending on the variety and how it's cooked. For raw sweet potatoes, these are rough average values:

Nutrient	Per 100 g
Calories	86 kcal
Protein	1.6 g
Fat	0.1 g
Carbohydrate	20.1 g
Fibre	3.0 g
Potassium	337 mg
Vitamin C	2.4 mg
Beta-carotene	about 8,500 µg

Important: the beta-carotene content depends heavily on the variety. Orange sweet potatoes contain much more than white or yellow ones.

Why sweet potato is interesting

• Beta-carotene: Orange varieties in particular contain a lot of provitamin A. Your body can make vitamin A from it, depending on your individual needs and how much fat is in the meal.
• More fibre than many potato dishes: With the skin on, sweet potato provides a useful amount of fibre. That's especially interesting if you generally eat little fibre. You'll find more on the topic under linseed and psyllium husk.
• The glycaemic index depends heavily on how it's cooked: It's often claimed that sweet potatoes always have a much lower glycaemic index than potatoes. It isn't that simple. Variety, cooking time, mashing, baking or cooling all change the value considerably. Boiled sweet potatoes tend to come out moderate, while well-baked or very soft preparations come out higher.
• Potassium: Sweet potatoes provide potassium, which many diets fall short on. Avocado is another food with plenty of potassium.
• Purple varieties contain anthocyanins: These plant compounds are colourful polyphenols. The evidence on specific health effects in everyday life isn't always clear, but the group of compounds is well studied in nutrition science.

Sweet potato vs potato: what's actually true?

The claim that sweet potatoes are "miles better" than ordinary potatoes is too sweeping. Both have their strengths, depending on what you're after.

Where sweet potato scores:

• more beta-carotene, especially in orange varieties
• often a little more fibre
• a sweetish flavour that works in both savoury and sweet dishes
• interesting colour varieties with different plant compounds

Where the ordinary potato scores:

• usually a little less sugar
• also contains plenty of potassium
• a large portion for relatively few calories
• interesting when boiled and cooled, because of resistant starch

Take care with the glycaemic index. Individual values from tables are of limited use in everyday life. What matters is the whole meal: fat, protein, fibre and portion size all affect the glycaemic response. If you're interested in how carbs fit into your everyday eating, our guides to low-carb eating and calorie deficits are worth a read too.

How to use sweet potato

Sweet potatoes can be boiled, steamed, baked or roasted in the oven. The skin is edible if you scrub them well. For a balanced meal, pair them with some protein and a little fat.

Handy combinations:

• with pulses, tahini or a yoghurt dip
• with olive oil, herbs and roast veg
• as a base for bowls with quinoa, leafy greens and pumpkin seeds
• as oven wedges instead of chips from highly processed frozen products

Kitchen tips:

• Cook gently: Steaming or baking at a moderate temperature keeps texture and flavour.
• Add some fat: A little fat, such as olive oil or nut and seed butter, makes sense for absorbing the fat-soluble carotenoids.
• Don't overcook if you want bite: Very long baking or mashing changes the texture and can raise the glycaemic index.
• Good for meal prep: Cooked cubes keep well in the fridge and work in bowls, salads or breakfasts. More in our guide Meal prep for beginners.

Buying and storing sweet potatoes

When buying, look for firm skin without soft spots, deep bruises or mould. Small scars are usually fine; large damaged areas less so. The heavier the sweet potato feels for its size, the fresher it often is.

Store sweet potatoes somewhere cool, dry and dark, but not in the fridge. Temperatures that are too low can spoil the flavour and texture. Around 12 to 16 °C is ideal. In good conditions they keep for one to two weeks, sometimes longer. Pieces you've already cut belong in the fridge and should be used within two to three days.

Possible side effects / take care if

Sweet potatoes are generally well tolerated. A few points are still worth knowing:

• Oxalates: Like many plant foods, sweet potatoes contain oxalates. For most people that's not a problem, but if you're known to be prone to certain kidney stones, your total intake may matter.
• Watch the FODMAP amount: Small portions are often tolerated better; larger amounts can cause symptoms in sensitive people. If this is relevant to you, read our guide to the low-FODMAP diet too.
• Avoid one-sided judgements: Sweet potatoes are a nutrient-rich food, but no substitute for an overall balanced diet with veg, protein sources, pulses, wholegrains and good fats.

Recipes with sweet potato

Here are a few ideas to explore:

• Vegan recipes with sweet potato, pulses and tahini
• Breakfast recipes with sweet potato waffles or savoury bowls
• Vegan recipes for roast veg with sweet potato and chickpeas
• Breakfast recipes for sweet potato hash with egg or tofu

FAQ

Is sweet potato healthier than ordinary potato?

Not across the board. Sweet potatoes contain more beta-carotene and often a little more fibre. Ordinary potatoes are also nutrient-rich, filling and versatile. Which one suits you better depends on your dish and your goals.

Does sweet potato really have a lower glycaemic index?

Partly, but not always. The GI depends heavily on the variety and how it's cooked. Boiled sweet potatoes can come out moderate, baked or mashed ones sometimes higher. The whole meal matters more than a single value from a table.

Can you eat the skin?

Yes, as long as the sweet potato is scrubbed well and has no spoiled spots. With the skin on, you also get extra fibre.

Which colour has the most nutrients?

Orange varieties contain a particularly large amount of beta-carotene. Purple varieties provide anthocyanins. White or yellow varieties usually taste milder but generally contain less of these colour-specific plant compounds.

Summary

The sweet potato is a versatile storage root with interesting nutrient profiles, especially the orange- and purple-fleshed varieties. It isn't better than the ordinary potato on every count, but it's a useful addition to varied meals, with fibre, carotenoids and an easy everyday source of carbs.