Contents
What it is
The kiwifruit is the fruit of a climbing vine native to the Yangtze valley in China, which is why its original name was Chinese gooseberry. It was taken to New Zealand in the early twentieth century and renamed there after the country's bird. Green and gold varieties are both common, the gold less acidic and sweeter. It contains actinidin, a protein-digesting enzyme, which stops gelatine from setting and can turn dairy bitter if the two sit together. That same property makes it useful for tenderising meat.
Scientific name Actinidia deliciosa
Kiwi holds nearly twice the vitamin C of an orange. But recent research has focused elsewhere.
In randomised trials on chronic constipation, two kiwifruit a day matched or beat prunes and psyllium for improving bowel movements, with less abdominal discomfort. The explanation is its unusual fibre structure, which holds on to water.
Key benefits
- Moderate evidence
It improves bowel frequency and comfort
This comes from a meta-analysis of 7 randomised trials (399 participants). The firmest finding is relief of abdominal pain, rated moderate certainty. Weekly bowel movements rose by 1.36 over placebo, but the confidence interval crossed zero — the result was not statistically significant — and the certainty was rated low. Against psyllium, kiwifruit did slightly better on both frequency and stool softness. Unlike stimulant laxatives, it is not habit-forming.[1]
- Nutrition data
Exceptionally dense in vitamin C
93 mg per 100 g, 1.8 times an orange (53 mg). But one green kiwi is only about 70 g, so around 65 mg — just short of the 75–90 mg adult requirement. Two clear it comfortably, and gold kiwi is concentrated enough that one will do.
- Early research
Actinidin aids protein digestion
In lab and animal work, kiwi's protease actinidin speeds the breakdown of meat and dairy proteins in the stomach — the same principle behind using kiwi to tenderise meat. In a randomised human trial, however, only the timing of amino acid appearance shifted: the total amount of essential amino acids absorbed was no different.[2]
- Early research
It appears in sleep quality research
A small trial found better sleep duration and efficiency after four weeks of eating two kiwifruit an hour before bed. The sample was small, so treat it as preliminary.[3]
How to eat it well
- The skin is edible and substantially increases the fibre. Scrub it, or choose gold kiwi if the fuzz bothers you.
- Do not let it sit in dairy. Actinidin breaks down milk protein and turns it bitter. Add it to yoghurt right before eating.
- To ripen a hard one, put it in a paper bag with an apple.
- Do not marinate meat longer than 30 minutes or the texture collapses.
- For constipation, follow the studied protocol: two a day, consistently.
How to read the grades
Each benefit carries a label showing how far research on people supports it. Grades differ between items even within the same ingredient.
- Nutrition data
- A fact verifiable from food composition databases or health authorities. This is a different kind of statement from a clinical effect.
- Strong evidence
- Consistently confirmed across randomised controlled trials or meta-analyses.
- Moderate evidence
- Human studies exist, but effect sizes are small or results are mixed.
- Early research
- Cell or animal work, or small preliminary studies.
- Not established
- Commonly claimed, but not confirmed in studies on people.
What to watch out for
- With latex, avocado or banana allergy, cross-reaction is possible. Kiwi is among the more common food allergens in children.
- It contains oxalate, so avoid large amounts with a history of calcium oxalate stones.
- Actinidin can make the tongue tingle or sting. Cooking removes this.
- On warfarin, keep vitamin K intake steady.
Nutrition
Approximate values per 100 g edible portion.
- Calories
- 61 kcal3%
- Carbohydrates
- 14.7 g5%
- Fiber
- 3.0 g11%
- Sugars
- 9.0 g
- Protein
- 1.1 g2%
- Vitamin C
- 93 mg103%
- Vitamin K
- 40 µg33%
- Vitamin E
- 1.46 mg10%
- Potassium
- 312 mg7%
Percentages are of the US FDA Daily Value for adults and children 4 and over. National reference intakes differ by sex and age.
Calculate this alongside other ingredients →
Key nutrients
By health concern
Compare with
Sources
The databases and health authorities this article's nutrition figures and health statements draw on.
- 1Kiwifruit and Kiwifruit Extracts for Treatment of Constipation: A Systematic Review and Meta-AnalysisMeta-analysisEltorki M, et al. Can J Gastroenterol Hepatol 2022PMID 36247043
- 2The impact of Hayward green kiwifruit on dietary protein digestion and protein metabolismClinical trialPark S, et al. Eur J Nutr 2021PMID 32970234
- 3Acute effects of fresh versus dried Hayward green kiwifruit on sleep quality, mood, and sleep-related urinary metabolites in healthy young men with good and poor sleep qualityClinical trialKanon AP, et al. Front Nutr 2023PMID 36998905
- 4USDA FoodData CentralFood composition database
- 5NIH Office of Dietary SupplementsHealth authority
- 6PubMedResearch literature
