Kiwifruit have just come into season and you should start to see them everywhere. The sweet, yet tart, hairy fruits are delicious and fun to eat. They are packed full of vitamin C (perfect for supporting your immune system), vitamin K (great for bones, especially for those menopausal ladies), carotenoids (including lutein and zeaxanthin) and antioxidants (so many antioxidants). These green gems are healthy on so many levels.
Because I want to be specific, let’s look at the details.
Studies on the effect of kiwifruit and the cardiovascular system have been completed. Reports support kiwifruit consumption and suggest that the fruit positively impacts the platelet aggregation (or blood clot formation) and plasma lipids (or cholesterol). Two or three kiwifruit per day, for 28 days was found to reduce platelet aggregation response to collagen by 18% and lowered blood triglycerides by 15%[1]. Further to this, a different study found that 3 kiwifruits per day decreased blood pressure by 10 and 9nm Hg along with a 15% reduction in platelet aggregation[2].
The vitamin C content of kiwifruits is huge. Depending on various factors (including location of growth, maturity at harvest, time of harvest, fertilisers, etc.) kiwifruits contain 2-3 times more vitamin C than oranges or strawberries. This stack of vitamin C has the potential to significantly impact (and improve) your immune system, your oxytocin production, your skin health, the health of your DNA, and many other functions. Vitamin C is involved in both defending your body against invading pathogens and via supporting the first responders[3]. A study looking at elderly people with upper respiratory tract infections, found that 4 kiwifruit per day reduced the severity and duration of the infection[4]. The effect of kiwifruit has been reported to upregulate several immune and DNA and repair -related genes[5]. Recognising these benefits suggests a myriad of potential.
Due to the vitamin C content, kiwifruit has the ability to increase your iron absorption, aid your gum and teeth health, reduce free radical activity and provide protection from oxidative stress. Plus, a whole lot more.
Moving away from vitamin C and the immune benefits, kiwifruit is also great for sleep. Kiwifruits are rich in antioxidants and serotonin, and this may be the reason kiwifruits have been found to be beneficial in the treatment of sleep disorders. A 2011 study found that consuming 2 kiwifruits 1 hour before bedtime, nightly, for 4 weeks lead a 28% reduction in waking time after sleep onset, a 35% reduced sleep onset latency and a 13% increase in total sleep time[6].
More studies looking at the benefits of kiwifruits highlight the impressive bowel function benefits, particularly in those with IBS and/or constipation. The dietary fibre of kiwifruit is a mixture of both soluble and insoluble fibres, providing an increase in both water retention in the bowels, and colonic volume[7].
In addition to this bowel benefit, kiwifruit consumption was found to significantly improve overall gastric comfort and in particular bloating, when two kiwifruits were consumed with a high protein meal[8]. It does this via an enzyme found in kiwifruit that is believed to help digest protein[9]. Further to these digestive benefits, kiwifruit has been found to display an anti-inflammatory and antioxidant effect in the intestines[10], as well as providing a favourable benefit to the gastro microbiome[11] and supporting the integrity of the gut barrier[12]. If you are aware of the old saying ‘the gut is the seat to good health’, you can start to understand how these digestive benefits have the potential to create a wealth of health effects.
Enjoy kiwifruit this season and eat the skin too. Yes, it is hairy, but yes, it is so beneficial to your health!
[1] Duttaroy, A. K. and A. Jorgensen (2004). “Effects of kiwi fruit consumption on platelet aggregation and plasma lipids in healthy human volunteers.” Platelets 15(5): 287-292.
[2] Karlsen, A., et al. (2013). “Kiwifruit decreases blood pressure and whole-blood platelet aggregation in male smokers.” J Hum Hypertens 27(2): 126-130.
[3] Richardson, D. P., et al. (2018). “The nutritional and health attributes of kiwifruit: a review.” Eur J Nutr 57(8): 2659-2676.
[4] Hunter, D. C., et al. (2012). “Consumption of gold kiwifruit reduces severity and duration of selected upper respiratory tract infection symptoms and increases plasma vitamin C concentration in healthy older adults.” Br J Nutr 108(7): 1235-1245.
[5] Skinner, M. A., et al. (2011). “Gold kiwifruit ( Actinidia chinensis ‘Hort16A’) for immune support.” Proc Nutr Soc 70(2): 276-280.
[6] Lin, H. H., et al. (2011). “Effect of kiwifruit consumption on sleep quality in adults with sleep problems.” Asia Pac J Clin Nutr 20(2): 169-174.
[7] Wilkinson-Smith, V., et al. (2019). “Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers.” Aliment Pharmacol Ther 49(6): 759-768.
[8] Wallace, A., et al. (2017). “A Pilot Randomized Cross-Over Trial to Examine the Effect of Kiwifruit on Satiety and Measures of Gastric Comfort in Healthy Adult Males.” Nutrients 9(7).
[9] Kaur, L. and M. Boland (2013). “Influence of kiwifruit on protein digestion.” Adv Food Nutr Res 68: 149-167.
[10] Ciacci, C., et al. (2014). “The kiwi fruit peptide kissper displays anti-inflammatory and anti-oxidant effects in in-vitro and ex-vivo human intestinal models.” Clin Exp Immunol 175(3): 476-484.
[11] Ansell, J., et al. (2013). “Modification of the colonic microbiota.” Adv Food Nutr Res 68: 205-217.
[12] Moughan, P. J., et al. (2013). “Kiwifruit, mucins, and the gut barrier.” Adv Food Nutr Res 68: 169-185.
About The Author - Samantha Mainland
Samantha is a highly educated Naturopath having graduated from both Southern Cross University with a Bachelor of Naturopathy, and University of Tasmania with a Bachelor of Medicine Management with Professional Honours in Complementary Medicine.