Root vegetables

| 19 November 2016
minute reading time
Root vegetables

Root vegetables are responsible for storing water and important nutrients for the leafy part of plants above the soil, and we get all these nutrients when we eat them! There’s even evidence to suggest that it may have been the tubers and roots in our ancestor’s diet that drove our intelligence.



Many people avoid high carb foods in the fear that they will cause weight gain, which is only a problem if you provide your body with more than it needs. Many dieters avoid carbs and replace them with protein sources – despite carbohydrate and protein both providing four calories per gram (fat provides nine calories per gram).

Some assume carbs to just mean sugars, but carbohydrates also include starch and fibre. Foods containing lots of simple sugars are easily absorbed and used by the body to produce a quick spike in blood sugar – known as high glycaemic index (GI) and high glycaemic load (GL). GI measures how quickly a food converts to glucose and GL measures how much it converts to glucose. These foods are great for when you need a quick supply of energy, but eating too much can make it hard for people with type 2 diabetes to control their blood sugar. High GI and GL foods include some processed foods, fizzy drinks, sauces, sweets, cakes and biscuits.

Cooked starchy root vegetables take longer for the body to break down and so give a slower, steadier supply of energy to the body.  These can help you feel fuller for longer, which in turn can help you to lose and maintain a healthy weight. Root veg is also full of fibre, which helps to reduce the impact of the carbohydrates on your blood sugar, and plays an important role in looking after your gut bacteria and lowering your risk of bowel cancer.



We should all be aiming for a minimum of 30 grams of fibre per day, and on average the UK is falling short. We all know that fibre is important for ‘regularity’, but many are less aware of its importance to our gut microbiota – the bacteria that live in our gut. Prebiotics are types of soluble fibre that bacteria in our gut are able to use, producing short-chain fatty acids. These provide energy to the cells of our intestines, but also have strong anti-inflammatory and anti-cancer properties. Diets high in fibre reduce the risk of bowel cancer significantly – this is one reason why vegans have a lower cancer risk overall.

Garlic contains a prebiotic compound called allicin, shown to have anti-inflammatory effects, which may help to lower blood pressure and blood cholesterol levels. Other prebiotics include inulins and galactans, found in root veg such as onions, garlic, Jerusalem artichokes and sweet potatoes.

When you cook a starchy vegetable such as potatoes and allow them to cool, this creates resistant starch. Resistant starch is not broken down by the body and does not cause a large spike in blood glucose – but it can be used as a prebiotic by your gut bacteria.

Incorporating more root veg into your diet is an easy and delicious way to boost your fibre intake. For example, just one cup of parsnip as a side dish provides 28 per cent of your recommended intake of fibre!



Polyphenols are plant chemicals that have beneficial health effects for us when we consume them. If you’re eating a healthy, varied vegan diet full of fruit and veg, you’ll be getting plenty!



Phytochemicals are compounds found in plant foods, many of which have positive health effects for us when we consume them. Carotenoids are found in – yep, carrots! They are found in other yellow, orange and red fruit and vegetables such as sweet potato, but in green leafy vegetables too. The consumption of carotenoids such beta-carotene has been linked to a reduced risk of diabetes, cardiovascular disease, lung cancer and bowel cancer. Beta-carotene is an antioxidant and is thought to protect the body from harmful molecules called free radicals which can cause damage to our cells. It can also be converted by the body into vitamin A, which is vital for the immune system, healthy skin and eyesight, protecting against age-related macular degeneration which is the leading cause of vision loss. To get more carotenoids in your diet, try accompanying a dish with sweet potato or carrot and swede mash instead of white potato.



Flavonoids are another class of plant chemicals found in many fruits and vegetables including red onions, white onions, celeriac, beetroot and radishes. Certain flavonoids have been shown to reduce the risk of breast, ovarian and bowel cancer, and to promote the healing of stomach ulcers that can sometimes become cancerous. They have also been shown to improve the control of blood sugar levels in people who are at risk of type 2 diabetes, prevent blood clots, and to inhibit the inflammation associated with asthma. Top tip – the flavonoids in red onion are concentrated in the outer layers, so avoid over-peeling when preparing them!


Vitamins and minerals

Root veg store water, vitamins and minerals for the plant, so they are packed full of goodness!

Vegetable% daily recommendation, per cup
Vitamin ACarrot400
Vitamin B6White potato30
Vitamin CWhite potato30
IronJerusalem artichoke28
PotassiumWhite potato20


The root of our intelligence

The processing and transmitting of information that occurs in our brain is very energy demanding – consuming up to 25 per cent of your body’s total energy, and up to 60 per cent of its glucose! Research suggests that it may have been the consumption of starchy tubers and roots such as potatoes that allowed the advancement of our intelligence. Humans have six genes for digesting starch while other primates just have two. This paired with the introduction of cooking would have made dietary glucose available in abundance for our growing brains!


Final word

In conclusion, we shouldn’t be avoiding these veg – we should be embracing them for all their earthy, knobbly goodness! They’re key to making a filling, homely meal and they’re packed full of vitamins, minerals, fibre and polyphenols.

About the author
Dr. Justine Butler
Justine joined Viva! in 2005 after graduating from Bristol University with a PhD in molecular biology. After working as a campaigner, then researcher and writer, she is now Viva!’s head of research and her work focuses on animals, the environment and health. Justine’s scientific training helps her research and write both in-depth scientific reports, such as White Lies and the Meat Report, as well as easy-to-read factsheets and myth-busting articles for consumer magazines and updates on the latest research. Justine also recently wrote the Vegan for the Planet guide for Viva!’s Vegan Now campaign.

View author page | View staff profile


Scroll up