Kiwi Fruit
Scientific Name(s): Actinidia chinensis Planch.
Common Name(s): China gooseberry, Chinese gooseberry, Kiwi fruit, Kiwi fruit extract, Kiwifruit, Tara fig, Tengligen
Medically reviewed by Drugs.com. Last updated on May 22, 2024.
Clinical Overview
Use
Limited small clinical studies have examined the role of kiwi fruit in relieving constipation. Immune system and antioxidant effects are being investigated. However, clinical trial data are lacking to recommend use for any indication.
Dosing
Clinical trials are lacking to inform therapeutic dosing. One kiwi fruit contains approximately 100 mg of vitamin C, which is approximately the same as the recommended US daily intake.
Contraindications
Contraindications have not been identified.
Pregnancy/Lactation
Kiwi has generally recognized as safe (GRAS) status when used as food.
Interactions
None well documented.
Adverse Reactions
Allergic reactions may occur in sensitive individuals. Cross-sensitivity with various pollens, latex, banana, and avocado is possible. Diarrhea has been reported following consumption of large quantities of kiwi fruit.
Toxicology
No data. Kiwi has GRAS status when used as food.
Scientific Family
- Actinidiaceae (Chinese gooseberry)
Botany
A. chinensis, the plant source of kiwi fruit, is native to China and Taiwan but is cultivated worldwide. Major producers include New Zealand, the United States (California), and Italy, but a considerable harvest is obtained from several other countries, including France, Israel, and Spain. The Hayward variety is the most commonly grown commercial cultivar because of its superior hardiness and long shelf life, but several other varieties, including one bearing a yellow-fleshed fruit, are cultivated. The plant is a vigorous, deciduous climber that grows to approximately 9 m in height, tolerating full sun or semishade. The scented flowers are pollinated by insects and appear in summer. Individual flowers are dioecious, with male or female flowers on separate plants. The egg-shaped fruit has a furry, brown skin and firm, translucent, emerald-green flesh with numerous small, edible, black seeds at the center. When ripe, the fruit is very juicy with an acidic flavor, often described as a mixture of strawberry and pineapple. "Tara fig" (Actinidia arguta) is a related American species grown domestically.(Akinnifesi 2007, Choudhary 2010, Duke 2002, USDA 2022)
History
Kiwi fruit was originally known as Chinese gooseberry, but after aggressive marketing by New Zealand fruit growers, it became known as the kiwi fruit, partly because of its resemblance to the small, brown, flightless bird. It has been used in China as the basis for flavorful wine and has a long tradition of use as a beverage. Kiwi juice has been used in some cultures as a traditional meat tenderizer. Other reported traditional uses include the treatment of urinary calculi and use as a diuretic, febrifuge, and sedative.(Akinnifesi 2007, Choudhary 2010, Duke 2002)
Chemistry
Kiwi fruit is a good source of triterpenoids, polyphenols, vitamin C, carbohydrates, amino acids, and minerals.(He 2019) Kiwi fruit also contains high concentrations of folate, potassium, magnesium, copper, and carotenoids, such as lutein and zeaxanthin. Isoflavones and vitamin E are also present. The main protein component of kiwi fruit is actinidin, a thiol protease, which accounts for approximately 50% of the fruit's soluble protein content and is also its major allergen. The gene for actinidin has been sequenced. The proteolytic activity of actinidin is similar, but not identical, to that of papain. A glycoprotein inhibitor specific for pectin methylesterase has also been isolated from the fruit; it is ineffective against other polysaccharide-degrading enzymes, such as polygalacturonase and amylase.(Balestrieri 1990, Duke 2002, Fu 2011, Lahlou 2001, Naylor 1989, Pastorello 1996, Pastorello 1998, Podivinsky 1989, Varughese 1992, Wang 2002)
The aroma profile and the aroma-active components of kiwi fruit have been extensively investigated.(Naylor 1989) More than 80 compounds have been identified in the volatile fraction of kiwi fruit; approximately 35 components appear to contribute to the aroma of kiwi fruit puree. The composition of the volatile fraction changes rapidly as the fruit matures from fresh, mature, to overripe, with a decrease in C6 compounds such as hexanal, hexenol, and ethyl butyrate, as well as an increase in terpene esters. The major compounds isolated from fresh puree include 3-methyl-2-butanone, 3-hydroxy-2-butanone, (E)-2-hexenal, ethyl 3-hydroxybutyrate, phenylethyl alcohol, alpha-terpineol, and geraniol. None of the flavor compounds are unique to kiwi fruit.(Jordán 2002, Santoni 2013)
Several antimicrobial compounds have been isolated from kiwi fruit. Seven phytoalexins were isolated from a methanol extract of the unripe fruit that had been previously wounded and inoculated with a fungus. The isolated antimicrobial agents included a novel triterpene phytoalexin (actinidic acid), as well as arjunolic acid, asiatic acid, and 23-hydroxytormentic acid. A single-chain, antifungal, thaumatin-like protein, thought to be the only defense protein present in kiwi fruit, has also been identified.
Kiwi seed oil has a high content of omega-3 fatty acids. The roots, which are used in traditional Chinese medicine, contain triterpenoids that are weakly cytotoxic in vitro.(Cravotto 2011, Xu 2010)
Uses and Pharmacology
Anti-inflammatory activity
Animal data
Anti-inflammatory activity of A. chinensis has been demonstrated in vivo in mouse models. Anti-inflammatory potential of A. chinensis seeds mainly depends on the synergetic effect of polyphenols; a potential preventive role in a variety of inflammation-related diseases has been suggested.(He 2019)
Antimicrobial activity
In vitro data
In vitro experiments using skin, pulp, seed, and stem extracts showed bactericidal activity against Staphylococcus aureus, Streptococcus pyogenes, Streptococcus faecalis, Salmonella typhi, Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonia. Polyphenols from the seeds of A. chinensis showed significant bactericidal activity against Bacillus cereus, B. subtilis, Shigella flexneri, and S. typhi and were bacteriostatic against Bacillus thuringiensis.(He 2019)
A thaumatin-like antifungal protein isolated from kiwi fruit showed modest activity against Botrytis cinerea and weaker inhibitory activity against Mycosphaerella arachidicola, Coprinus comatus, and Physalospora piricola.(Wang 2002)
Antioxidant activity
In vitro and in vivo data
In a study evaluating total antioxidant and ascorbic acid content of various commonly consumed fruits and vegetables, kiwi fruit was found to have the highest concentration of ascorbic acid as well as strong antioxidant activity.(Szeto 2002) A study comparing the carotenoid content of a variety of foods showed a higher proportion of lutein and zeaxanthin (the major carotenoids found in the human eye) in kiwi fruit than in spinach.(Sommerburg 1998) In vitro and in vivo studies have shown antioxidant activity of kiwi fruit.(Iwasawa 2011, Karlsen 2011) Assays based on superoxide dismutase, glutathione, ALT, AST, oxidative DNA damage, and lipid oxidation have confirmed that A. chinensis possesses antioxidant capacity. Appropriate extraction methods, genotypes, and plant parts can be screened to maximize the antioxidant properties of A. chinensis.(He 2019)
Cancer
A critical literature review investigated 8 published studies (5 in vitro studies, 2 human intervention trials, 1 in vivo study, and 1 in-human study). Results suggest that kiwifruit supplementation may be associated with direct and indirect anticancer effects. Direct effects are likely due to ascorbic acid−mediated reduction of DNA oxidative injury and cytotoxic effects on cancer cell lines, while indirect effects are more likely attributable to enhanced daily bowel movements and increased intestinal fecal content of lactic acid bacteria, which would ultimately contribute to lowered risk of malignancies, especially colorectal cancer.(Lippi 2020)
In vitro data
Kiwi plant roots are used in traditional Chinese medicine and contain triterpenoids that have weak inhibitory effects against growth of several human cancer cell lines in vitro.(Xu 2010) A. chinensis root extracts have attenuated proliferation and metastasis of hepatocellular carcinoma cell lines by inhibiting epithelial-mesenchymal transition.(Fang 2019) A. chinensis has also prevented the proliferation and migration of gastric cancer cell lines associated with apoptosis, ferroptosis activation, and mesenchymal phenotype suppression.(Gao 2020) Further in vitro experiments demonstrated that the root of A. chinensis inhibits hepatocellular carcinoma cells through Laminin subunit beta-3.(Hou 2018)
Cholesterol-lowering activity
Animal data
Studies in hypercholesterolemic mice fed preparations containing kiwi fruit and hawthorn have shown positive results.(Xu 2009)
Clinical data
Among healthy volunteers in a randomized crossover study, 28 days of kiwi fruit consumption reduced platelet aggregation (P<0.05) and plasma triglyceride levels (P<0.05) compared with controls. No effects on HDL or LDL cholesterol were observed.(Duttaroy 2004, Skinner 2011)
GI effects
Clinical data
The fiber content of kiwi fruit is suggested to be approximately 3.5 g per 100 g of fruit.(Chan 2007, Duke 2002) A small, unblinded clinical trial evaluated the effect of kiwi fruit on colon transit time and defecation frequency in healthy adults and in those with irritable bowel syndrome. Improved bowel function with kiwi fruit consumption compared with placebo was observed.(Chang 2010) Further small studies support anecdotal reports of the laxative effects of kiwi fruit.(Chan 2007, Rush 2002) In a randomized controlled crossover trial in mildly constipated adults (N=32), daily consumption of 3 gold-fleshed kiwifruit was associated with a significant increase of 2 complete spontaneous bowel movements per week and a reduction in GI discomfort. Number of complete spontaneous bowel movements was significantly greater with kiwifruit compared with baseline and comparator treatment (Metamucil) (P<0.05 for both comparisons).(Eady 2019) In a pilot randomized crossover trial in healthy adult men (N=10) examining effects of kiwifruit on satiety and measures of gastric comfort, results suggested that green kiwifruit (containing actinidin) may reduce bloating and other measures of gastric discomfort.(Wallace 2017)
Other studies reporting upper GI effects as secondary outcomes were identified in a systematic review that explored the effects of kiwifruit in healthy participants as well as patients with constipation (ie, functional constipation, IBS). Limitations included variations in study protocols, product form (ie, whole fruit, powder, extracts), study duration (1 to 28 days), controls (ie, prunes, psyllium, glucose, maltodextrin, none), and participant characteristics (ie, healthy versus constipated); study populations ranged from 10 to 184. Overall, sparse evidence reflected positive effects of kiwifruit on upper GI health. Specifically, evidence of benefit was noted for dyspepsia (high quality), abdominal discomfort/pain (good quality), and distention/bloating (good quality) particularly with consumption of 2 or 3 whole kiwifruit per day.(Bayer 2022)
Immune function
Animal data
Effects of kiwi fruit extracts on immune function have been studied in mice.(Edmunds 2012, Lin 2011, Skinner 2011)
Clinical data
Limited preliminary clinical studies suggest that consumption of kiwi fruit may assist in upregulating the immune system.(Skinner 2011) A small study in elderly patients found that kiwi fruit consumption reduced the severity and duration of symptoms associated with upper respiratory tract infections. However, indicators of immune function (natural killer cell activity and phagocytosis) did not differ from those of the comparator banana group.(Hunter 2012)
Dosing
Clinical trials are lacking to inform therapeutic dosing. One kiwi fruit contains approximately 100 mg of vitamin C (approximately the recommended US daily intake).(Szeto 2002)
In humans, the bioavailability of vitamin C from skinless kiwi fruit consumption was equal to that of a synthetic chewable vitamin C tablet.(Carr 2013a, Carr 2013b)
Pregnancy / Lactation
Kiwi has GRAS status when used as food. Dosages higher than amounts found in foods should be avoided; safety and efficacy have not been established.
Interactions
None well documented. The serotonin concentration of the fruit is approximately twice that of tomatoes and one-third that of bananas. Therefore, ingestion of kiwi fruit can increase urinary excretion of 5-hydroxyindoleacetic acid and may interfere with laboratory analyses of this serotonin byproduct.(Feldman 1985)
The 90% ethanol extract of A. chinensis root (50 mcg/mL) exhibited inhibitory activities on CYP2C9, CYP2D6, and CYP3A4 in human liver tissue. The inhibitory effect of the crude extract could be largely attributed to the presence of triterpenoids. It should be noted that the combination of crude extracts of these triterpenoids with other medicinal herbs or drugs may lead to drug interactions with CYP enzymes at pharmacokinetic and pharmacodynamic levels; caution is warranted when consuming A. chinensis fruit when taking other herbal or drug products.(He 2019)
Adverse Reactions
Allergy to kiwi fruit and the kiwi vine is well documented. This includes oral allergy syndrome, contact dermatitis, Kounis coronary syndrome, and anaphylaxis. Trace amounts of kiwi fruit have been responsible for some of these reactions.(Gázquez 2010, Guler 2014, Mancuso 2001, Mempel 2003, Rademaker 1996, Shimizu 1995, Veraldi 1990) Although acute pancreatitis in the course of an allergic reaction to a food substance is rare, a case report describes a patient with repeated attacks of acute pancreatitis secondary to kiwi fruit ingestion.(Gastaminza 1998)
Cross-reactivity of kiwi fruit with several other allergens, including birch and meadow fescue grass pollens, latex, avocado, and banana has also been reported.(Alemán 2004, Gavrović-Jankulović 2002, Möller 1998, Voitenko 1997) The major allergen appears to be the proteolytic enzyme actinidin. Industrial heating and homogenizing techniques appear to diminish the likelihood of allergic reactions.(Fiocchi 2004)
Consumption of relatively large quantities of kiwi fruit may result in diarrhea.(Skinner 2011)
Toxicology
Information is lacking. Kiwi has GRAS status when used as food.
Index Terms
- Actinidia arguta
- Tara Fig
References
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