Sweet potato

What is a sweet potato?

The sweet potato is a starchy, sweet-tasting root vegetable. They have a thin, brown skin on the outside with coloured flesh inside – most commonly orange in colour, but other varieties are white, purple or yellow. You can eat sweet potatoes whole or peeled, and the leaves of the plant are edible too.

They may both be called ‘potatoes’, but sweet and white potatoes are not actually related. Botanically, the sweet potato belongs to the bindweed or morning glory family, whereas the white potato sits in the nightshade family.

Nutritional value of sweet potato

Sweet potatoes are a rich source of fibre as well as containing a good array of vitamins and minerals including iron, calcium, selenium, and they’re a good source of most of our B vitamins and vitamin C. One of the key nutritional benefits of sweet potato is that they’re high in an antioxidant known as beta-carotene, which converts to vitamin A once consumed.

80g of sweet potato, or about one medium potato, counts towards one of your five-a-day, unlike white potato which does not.

Fruit and vegetables are high in antioxidants, compounds that help defend the body against damage by ‘free radicals’.

Are sweet potatoes good for digestion?

Sweet potatoes are high in fibre, which has been shown to promote a healthy digestive system. Research so far has only been conducted on animals, but it would appear that the high phytosterol content of sweet potatoes does have a protective effect on the digestive system and may be important in the prevention and management of duodenal and gastric ulcers, including those due to NSAIDS (non-steroidal anti-inflammatory drugs such as ibuprofen).

Are sweet potatoes safe for everyone to eat?

On the whole, sweet potatoes are an excellent addition to a balanced diet. However, they do contain something known as oxalates which binds calcium and other minerals. Too many oxalates in the diet may cause kidney stones and so should be eaten in moderation if you have existing kidney stones or are at high risk of developing them. If you are concerned, check with your GP.

How does cooking affect the nutritional value of sweet potato?

Cooking sweet potato does reduce its beta-carotene levels, although boiling appears to have a higher retention compared to baking. The good news however, is that cooking sweet potato appears to increase its vitamin C content.

Information on this page came from nutritionist Nicola Shubrook, via BBC Good Food.