Kiwi – unpeeled: How two a day may be key to fresher skin and better sleep… and whether or not you really need to eat the skin

Tart, green and fuzzy, they may not always seem the most appealing snack. 

But experts say the humble kiwi comes with a whole host of benefits – for our mood, digestion and even skin. 

Native to China since the 12th century, kiwi were traditionally used for medicinal purposes. 

The fruit was administered for stomach issues as well as to aid digestion, ancient records show. 

In the early 20th century, after horticulturists brought the plant’s seeds to New Zealand – where it was renamed for its resemblance to the country’s furry, brown national bird – the kiwi became a popular snack amongst stationed US servicemen.

Today, the fruit is one of New Zealand’s defining agricultural products – making more than NZ$1billion in export revenue. 

And recent research shows the kiwi can benefit more than just the digestive system. 

Experts speaking to the Daily Mail say that kiwis can help with a range of health issues. 

‘They’re rich in fibre, vitamin C, potassium and plant compounds known as polyphenols – all of which play supportive roles in overall health when included as part of a balanced diet,’ explained nutritionist and founder of the Rhitrition Clinic Rhiannon Lambert.

‘Kiwis are one of the most underrated fruits out there!’

So, read on for our expert-led guide on the myriad health benefits of the kiwi – and how to harness them…

Do kiwis help with constipation?

Packed with fibre, kiwis are amazing at helping digestion – and keeping you regular. 

In fact, two to three kiwis a day is actually a recommended treatment for people suffering with constipation, according to British Dietary Association guidelines.

Clinical trials have also shown that kiwis can help reduce side effects like bloating. 

The fruit does this because of its impressively high quantities of both soluble and insoluble fibre, explains registered dietician Nichola Ludlam-Raine. 

‘Soluble fibre, which you find in the fleshy part of the fruit, is good for heart health and cholesterol,’ she said. 

‘Insoluble fibre, meanwhile, helps with digestion and keeping you regular.’ 

Fibre helps the digestive system by adding bulk and softening stool. 

Soluble fibre, meanwhile, dissolves into a gel which feeds good bacteria in the gut, making it better able to digest food in the future, and providing the body with essential nutritents.

And just one kiwi contains up to 3g of fibre.  

To up the dose of fibre even more, says Ms Ludlam-Raine, eat the kiwi’s skin. 

‘This should increase the fibre content by 50 per cent. And if you gently rub off some of the furry coating, tastes great too,’ she explained.

Ms Ludlam-Raine advises chopping a kiwi – skin on – into your fruit salad, or have it on top of yoghurt, with a handful of similarly high-fibre linseeds. 

So kiwis help you sleep?

Kiwi fruits may even help improve sleep length – and quality – say experts. 

Researchers from Northumbria University’s Sleep Research Centre, the University of Limerick and the Sports Ireland Institute in Dublin found that eating two kiwis a night an hour before bed led to better quality and less interrupted sleep. 

This was likely due to the fruit’s high seratonin content – used by the body to create melatonin, the hormone responsible for sleep regulation – they concluded. 

Antioxidants in the fruit may also help by reducing stress levels and helping people to drop off, further research has shown. 

A Taiwanese study made similar findings. 

The same strategy – two nightly kiwis – helped middle-aged people with self-reported sleep disturbances to get to sleep more quickly and then sleep for longer. 

‘Kiwis are increasingly being discussed in relation to sleep and recovery due to their high levels of nutrients that are linked to sleep regulation and recovery processes in the body,’ said nutritionist Rhiannon Lambert.  

‘While this area of research is still developing and larger studies are needed, including kiwis as part of an evening snack may be a simple, food-first approach worth trying for those looking to support their sleep routine.’ 

So kiwis improve mood? 

Daily consumption of kiwis can also help boost your mood, studies show. 

A team of researchers from the University of Otago, New Zealand, conducted an eight-week study looking at 155 adults with low vitamin C.

Participants took either a vitamin C supplement, placebo, or two kiwi fruit daily then reported their vitality, mood, sleep quality and physical activity via smartphone surveys.

The results, published in the British Journal of Nutrition, showed that kiwi fruits improved vitality and mood within four days, with the effect of the boost peaking at around 14-16 days.

Vitamin C supplements, on the other hand, marginally improved mood until day 12.

‘Kiwis are one of the most underrated foods when it comes to vitamin C,’ says registered dietician Nichola Ludlam-Raine. 

‘Just one fruit contains double the daily recommendation for the nutrient.

‘It’s great for the immune system, and for plant-based iron absorption – as the body needs vitamin C to be able to process and use iron from non-meat sources.’ 

‘Vitamin C deficiencies are also associated with higher rates of depression, and the vitamin has been shown to improve mood.’ 

Do kiwis improve skin? 

Want youthful-looking skin? Try a kiwi or two. 

At least, that’s the advice of researchers at the University of Otago, based on a recent study published in the Journal of Investigative Dermatology. 

Eating two kiwis can provide enough vitamin C circulating through the blood as to have a beneficial effect on the skin, they concluded, reaching even the outermost layer, and boosting collagen production.

This, in turn, helps the skin renew to create thicker, healthier skin, explained the study. 

‘The body can’t produce vitamin C on its own, so kiwis are a great way to get your daily dose,’ says Ms Ludlam-Raine.

‘This will support collagen production – which slows down after we reach 25 – which helps keep the skin plump and elastic.’