Superfoods: Kiwi

Kiwifruit, also known as Chinese gooseberry, is a nutrient-dense berry known for its fuzzy brown skin and bright green flesh.

Beyond their appearance, the most noteworthy feature of kiwis is their exceptionally high vitamin C content, with golden varieties providing up to three times that of oranges. One medium green kiwifruit provides about 85 mg of vitamin C per 100 grams, while the golden varieties can deliver up to 161 mg of vitamin C per 100 grams.^1,2

This high vitamin C content could contribute to meaningful improvements in vitamin C blood levels. A study of 36 young men with below-optimal vitamin C status found that consuming half or two gold kiwifruit per day for 6 weeks significantly increased plasma vitamin C concentrations, with the higher dose raising levels to adequate status (>50 µmol/L).³

In addition to vitamin C, kiwis contain carotenoids, polyphenols, and dietary fiber—all of which can potentially benefit the immune system. Evidence from in vitro studies and animal models suggests that the compounds in kiwifruit may exert immune-modulating effects. Human intervention trials further indicate that regular consumption may reduce the severity of upper respiratory tract infections.⁴

Research also links regular kiwi consumption to improvements in digestive health.² For example, a systematic review and meta-analysis of 7 randomized, controlled trials found that kiwifruit or its extracts increased the frequency of spontaneous bowel movements, while reducing abdominal pain in individuals with constipation, compared to placebo.⁵

In addition, observational data link habitual kiwifruit intake with favorable metabolic markers. In a study of 1,469 participants, those who ate at least one kiwi per week had higher HDL cholesterol, lower triglycerides, reduced fibrinogen levels (a marker related to blood clotting and inflammation), and lower HOMA-IR values (indicating better insulin sensitivity), compared to those who ate less than one kiwi per week.⁶

Complementing these findings, a randomized controlled trial demonstrated that individuals with high-normal blood pressure or stage 1 hypertension who ate three kiwifruit per day for eight weeks experienced greater reductions in 24-hour systolic and diastolic blood pressure compared to those consuming one apple per day.⁷

While kiwifruit is typically eaten peeled and sliced, eating it with the skin on can further increase fiber intake. If consuming with the skin, wash the fruit thoroughly and bite into it like an apple.

References

1. Sivakumaran S, Huffman L, Sivakumaran S, et al. The nutritional composition of Zespri(R) SunGold Kiwifruit and Zespri(R) Sweet Green Kiwifruit. Food Chem. 2018 Jan 1;238:195-202.
2. Richardson DP, Ansell J, Drummond LN. The nutritional and health attributes of kiwifruit: a review. Eur J Nutr. 2018 Dec;57(8):2659-76.
3. Carr AC, Bozonet SM, Pullar JM, et al. Human skeletal muscle ascorbate is highly responsive to changes in vitamin C intake and plasma concentrations. Am J Clin Nutr. 2013 Apr;97(4):800-7.
4. Stonehouse W, Gammon CS, Beck KL, et al. Kiwifruit: our daily prescription for health. Can J Physiol Pharmacol. 2013 Jun;91(6):442-7.
5. Eltorki M, Leong R, Ratcliffe EM. Kiwifruit and Kiwifruit Extracts for Treatment of Constipation: A Systematic Review and Meta-Analysis. Can J Gastroenterol Hepatol. 2022;2022:7596920.
6. Recio-Rodriguez JI, Gomez-Marcos MA, Patino-Alonso MC, et al. Effects of kiwi consumption on plasma lipids, fibrinogen and insulin resistance in the context of a normal diet. Nutr J. 2015 Sep 15;14:97.
7. Svendsen M, Tonstad S, Heggen E, et al. The effect of kiwifruit consumption on blood pressure in subjects with moderately elevated blood pressure: a randomized, controlled study. Blood Press. 2015 Feb;24(1):48-54.