Kiwifruit - A True 'Superfood'

We're shining light on the humble kiwifruit! 

These nutrient-packed wee gems are in season, and we think they deserve a little more love! There are plenty of reasons to pop a few into your trolley this week, one of which is that they're currently super affordable. As for the other reasons? We get into those below. 

Historically known as Chinese gooseberries (native to China), kiwifruit are rich in fibre, vitamin C, folate, potassium, vitamin E, phytonutrients, and contain a proteolytic enzyme called actinidin. 

Kiwifruit have long been used in Chinese Medicine for gastrointestinal complaints, and Western science is supporting these benefits. 

Both green and gold kiwifruit contain a unique combination of soluble fibre, insoluble fibre, and polyphenols. Green kiwifruit, in particular, have higher amounts of actinidin (compared to golden kiwifuit), a proteolytic enzyme that helps break down protein in the stomach and small intestine. Some studies suggest that actinidin may help with symptoms of functional gastrointestinal disorders (like bloating and constipation), likely due to its action as a digestive enzyme. 

Interestingly, this enzyme is also what makes kiwifruit a natural meat tenderiser (also worth noting - it's the main allergen in kiwifruit!) 

Kiwifruit are rich in dietary fibre (another factor contributing to their gastrointestinal benefits), containing 2-3g per fruit - more if you eat the skin. Fibre recommendations are 25-30g per day, so adding one or two kiwifruit to your daily eating pattern is a simple and effective way to boost your intake. Fibre consists of carbohydrates that are unable to be digested in the small intestine. As a result, they pass to the large intestine, where they're broken down by the gut microbiota. Essentially, fibre acts as fuel for your microbes, generating by-products like short-chain fatty acids that support gut health and other body systems. Fibre also helps to bulk and soften the stool. Increasing fibre in the diet has various benefits, including enhanced satiety and reducing the risk of constipation and bowel cancer.

Research Highlights (all references for this newsletter are listed below):

• Eating two to three kiwifruit daily may improve stool frequency, consistency, and comfort in people with functional constipation and IBS-C.

• One study using MRI found that consuming two green kiwitruit per day increased water retention in both the small and large bowel in healthy individuals. This may explain the softer, more frequent bowel movements observed. 

Vitamin C Powerhouse

Kiwifruit are excellent sources of vitamin C, especially the golden variety.

• Gold kiwifruit: ~160mg of vitamin C per 100g

• Green kiwifruit: ~85mg per 100g

Vitamin C is water-soluble, and our bodies can't produce it, so we need to get it from our diet.

Why do we need vitamin C?

• It acts as an antioxidant, protecting cells from free radical damage

• It supports collagen production (important for wound healing)

• It enhances iron absorption from plant-based sources

• It plays a key role in our immune function

Our Take-Home Tip

• Make the most of kiwifruit while they're in season! Aim for 1-2 kiwifruit per day to support digestion, regularity, and overall nutrition. Enjoy them in smoothies, with your cereal, on yoghurt, tossed into salads, or as they are!

References 

Wilkinson‐Smith, Victoria, et al. "Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers." Alimentary pharmacology & therapeutics49.6 (2019): 759-768.

Eady, Sarah L., et al. "The effect of ‘Zesy002’kiwifruit (Actinidia chinensis var. chinensis) on gut health function: A randomised cross-over clinical trial." Journal of nutritional science 8 (2019): e18. 

Richardson, David P., Juliet Ansell, and Lynley N. Drummond. "The nutritional and health attributes of kiwifruit: a review." European journal of nutrition 57 (2018): 2659-2676. 

Chan, Annie On On, et al. "Increasing dietary fiber intake in terms of kiwifruit improves constipation in Chinese patients." World journal of gastroenterology: WJG 13.35 (2007): 4771.

Chang, Chun-Chao, et al. "Kiwifruit improves bowel function in patients with irritable bowel syndrome with constipation." Asia Pacific journal of clinical nutrition 19.4 (2010): 451-457.

Gearry, Richard, et al. "Consumption of two green kiwifruit daily improves constipation and abdominal comfort–results of an international multicentre randomised controlled trial." Official journal of the American College of Gastroenterology| ACG (2022): 10-14309