Sweetcorn

Originating from Central America, studies suggest that corn or maize (Zea mays) was domesticated in Mexico as early as 10,000 years ago. Archaeologists have found the remains of smaller plants with the characteristic rows of kernels on the cob. Selective breeding over the years has enabled farmers to cultivate larger varieties which are now grown all over the world. Maize has become the leading global staple cereal, with annual production exceeding one billion tonnes.

Sweetcorn and maize – what’s the difference?

An ‘ear’ of corn is made up of kernels on a cob, wrapped in a husk. ‘Sweetcorn’ refers to the kernels or the whole cob when eaten as a vegetable – when the kernels are still tender. It is grown in the UK as a very small-scale horticultural crop.

Maize, on the other hand, generally refers to crops grown in fields. In warmer climates, like that of the US, Mexico and China, maize may be harvested when fully mature and dry, when it is regarded as a grain rather than a vegetable. Ground into flour, it becomes cornmeal or maize flour and can be used to make tortilla wraps, grits, polenta and many other foods.

In the UK, US and many other countries, the majority of maize is used for animal feed. In the UK, it is often turned into silage, especially for dairy cattle, while much of the remainder is used in energy generation by anaerobic digestion. UK production rose to 228,000 hectares in 2019 from just 8,000 in 1973, and much of that was grown in the Southwest. Maize is a high-risk erosion crop as the plants leave soil exposed during much of the growing season and where maize replaces grassland, the risk of erosion is even higher, especially when planted on slopes.

A largescale shift towards a vegan diet could stop the continual expansion of animal feed crops, require far less land and enable a restoration of forests and grassland.

What are the nutritional benefits?

Corn sometimes gets a bad rap because it is rich in starchy carbs that release natural sugars when digested. Despite the amount of sugar in sweetcorn, it is not considered a high-glycaemic food because it is also rich in fibre which slows the release of its sugars. This fibre can help you feel fuller for longer between meals and supports healthy bacteria in your gut and this provides protection against bowel cancer and some other diseases.

A 2018 study suggests that regular consumption of whole grain corn [sweetcorn or maize flour as opposed to corn oil or syrup] lowers the risk of developing chronic diseases such as cardiovascular disease, type 2 diabetes and obesity and improves digestive health.

Sweetcorn is a good source of B vitamins and is rich in folate (vitamin B9), both essential for wellbeing, especially during pregnancy. Just one portion (85 grams) of tinned sweetcorn can provide almost a fifth of your daily folate needs. It’s also a good source of vitamin C, essential for normal growth and repair, supports your immune system and increases iron absorption. Vitamin C is an antioxidant, which means it helps protect our cells from damage that can lead to cancer and other diseases.

In case you’re wondering, tinned sweetcorn may lose some of its vitamin C, but it delivers the same amount of fibre as fresh corn and is often a cheaper alternative that’s available all-year-round. Research suggests that the antioxidant activity in sweetcorn increases significantly after being heated during processing, despite the decline in vitamin C content.

Carotenoids are the yellow, orange and red organic pigments that give the characteristic colour to pumpkins, carrots, parsnips, sweetcorn, tomatoes etc. Sweetcorn is a good source of lutein and zeaxanthin, which can benefit eye health and help protect against macular degeneration and cataracts. One study of middle-aged and older adults found a 43 per cent reduction in the risk of macular degeneration in those with the highest intakes lutein and zeaxanthin, compared to those with the lowest.

Corn also contains smaller amounts of vitamins E and K, along with minerals like magnesium and potassium and offers a small amount of protein too (over three grams in 100 grams, adults need 45 to 55 grams a day).

Blue corn benefits

Corn is usually yellow but there are white, blue and purple varieties. Darker varieties contain more health-beneficial phytonutrients (antioxidants) so look out for blue tortilla chips or buy blue maize flour to make homemade wraps or burritos – they have a lovely ‘nutty’ flavour.

How to cook it

Once sweetcorn is picked, its sugars start turning to starch so is best eaten soon after picking. If you are able to grow your own, put a big pan of water on, ready and waiting to cook the cobs as soon as you pick them. Failing that, buy the freshest corn you can find – its leaves pale over time so look for nice green ones and peek inside the husk to see if the kernels are bright yellow and plump – then store it in the fridge until you are ready to cook it.

Sweetcorn is easy to cook and can be steamed, boiled, baked or grilled on its own or drizzled with vegan butter and a pinch of paprika, chilli powder or black pepper. Whether you serve it whole on the cob or from a can, sweetcorn makes a delicious addition to many dishes, including creamy chowders, salsas, fritters, pizzas, salads and more. It also makes a great side dish at a barbecue. Maize flour can be made into corn tortillas for a Mexican meal and provides more fibre, nutrients and less fat than tortillas made with wheat flour. Popcorn can be made by heating dried kernels when its starchy centre, that holds some moisture, will expand and ‘pop’ when they’re heated!

A word of caution

Corn contains proteins known as zeins that are related to gluten. In rare cases, people with coeliac disease may experience problems but not usually as much as with gluten. It can also trigger symptoms in some people with IBS.

For most people, however, sweetcorn, is a versatile and nutritious addition to a healthy diet.