What is a kumquat?
Kumquat is a fruit that is the smallest in the citrus family. It is a golden-yellow oval-shaped fruit that is native to China and has been grown for over 1600 years. Countries like Japan, India, North America and Southeast Asia have also started cultivating the fruit. It bears the botanical name Citrus japonica and falls under the genus Fortunella, named after Robert Fortune, who introduced the fruits to Europe.1
Kumquat has the appearance of a mini orange with a sweet yet tangy flavour. Otherwise known as Fortunella, the name kumquat is believed to have got its roots from the Chinese word “chin kan” which means gold orange. Other sources attribute its name to the coining of the two words “kum” and “quat” which means golden and good fortune in Cantonese Chinese.
This fruit is not your regular citrus fruit. It has a unique quality that distinguishes it from other citrus plants. Its peel is edible in addition to its sensory and aromatic characteristics. Also, it has few seeds, making it possible to eat the fresh kumquats whole and spit out the seeds if you like.
Despite its unpopularity, kumquat is a highly nutritious, low-calorie fruit. It has several types and is identified by their shape, colour and taste. Some of them include:
Also known as round kumquat, this is the ancient Chinese kumquat that is round or slightly oval. It has smooth, golden-yellow skin with notable oil glands. They have very few seeds (one to six), and the pulp is sour and juicy. This species is often used to prepare jams, jellies and marmalades.
Known as the oval kumquat because of its shape, it has a sour pulp, a sweet peel and only a few seeds (2 to 5). It also has a sub-variety known as ‘centennial variegated’ because of the yellow and green stripes on its peel.
- Meiwa Kumquat:
This species, also known as Fortunella crassifolia, is considered to be a natural hybrid between Marumi and Nagami kumquats. It’s an oval or round shape. The fruit is very thick and sweet and is regarded as the best for eating fresh.
- Hong Kong Kumquat:
This is the tiniest and most primitive variety of kumquat. It is bitter and has more seeds and a limited amount of pulp. The kumquat tree is mainly cultivated as an ornamental plant. Some regard it as the ‘golden bean kumquat’.2
This variety of kumquat has a powerful citrus flavour and several nutrients that make it ideal for an appetizer as well as a snack. Generally, kumquats are eaten fresh or processed foods such as pastries, candies and preserved fruits. They are often used in the preparation of kumquat juice, jams, jellies, fruit salad and vinegar.
Other varieties include hybrids from any of the above species. Some include the Indio mandarinquats, Fukushu kumquats, Nordmann seedless kumquats, the calamondin, etc.
Health benefits of the kumquat
As tiny as this fruit is, it is packed with plant compounds that are rich in antioxidant and anti-inflammatory properties.3
Below are some of the health benefits of kumquat:
- Promotes dietary/gut health:
Kumquats are great sources of dietary fibre that aid digestion. Not only does this fibre help to alleviate disease conditions such as constipation, gastritis, abnormal bowel movements, diarrhoea, colitis, etc., but it also helps to promote gut health and immunity by acting as food for the good bacteria in the intestines.
- Lowers cholesterol and prevents heart disease:
Sometimes, free radical-damaged low-density lipoproteins (LDL) cause an inflammatory reaction that can lead to the building up of cholesterol in the blood vessels. If cholesterol reacts with toxic free radicals in the arteries, it can cause a condition known as atherosclerosis. Such high levels of cholesterol can also lead to stroke, heart failure and other heart problems. The antioxidants present in kumquats help to reduce cholesterol levels and blood pressure. In a study conducted on rats placed on high-fat diets, kumquat was found to reduce blood fat and cholesterol levels.8
- Fights cancer:
Along with other antioxidants found in kumquat fruit, apigenin, which is a type of flavonoid, may fight against cancer.9 It acts on cancer cells, killing them stopping their growth and spreading to other cells. The antioxidants in kumquat aim to kill free radicals that promote the growth of cancer cells.
- Boosts immunity:
Our immune system is made up of a variety of cells that ensure the body performs optimally. Cells like macrophages and lymphocytes play a vital role in protecting the body from diseases caused by bacterial and viral infections. They act by attacking and killing the pathogens that enter our bodies.
A toxic type of lymphocyte known as natural killer cells targets and destroys cancerous cells or cells affected by viruses. A study11 showed that the active phenolic compounds10, beta-cryptoxanthin and limonene, when extracted from raw kumquat, heightened the ability of the natural killer cells in an in vivo model and mediated the anti-stress effect.
Kumquats also contain high vitamin C content, which helps them build white blood cells, support the immune system, and protect it from the noxious effect of free radicals.
- Helps in lowering blood sugar
The fibre content present in kumquat helps to slow the absorption of sugar from food, slow digestion, and reduce further craving for food. This plays a role in limiting the number of calories you consume, which is great for controlling your insulin levels and managing diabetes in patients with diabetes. It equally has low sugar and zero glycemic index, making it a great choice of fruit for people at risk of developing type 2 diabetes. When kumquat extract was used on obese and diabetic mice, it was observed to lower blood sugar levels and insulin resistance.4
- Helps with anti-inflammatory effect:
The presence of any harmful pathogen in our body triggers our immune system to react and kill the threatening pathogen in a process known as inflammation. Among the several compounds that kumquat fruit contains, flavonoids and concern are the ones with anti-inflammatory properties. This has made it possible to extract essential oil for topical application to relieve arthritis pain and inflammation.
Flavonoids found in kumquat include naringenin, hesperidin, kaempferol, quercetin, luteolin, and DGPP, a C-gylcoside. DGPP is the major flavonoid, a derivative of phloretin, which has been found to reduce inflammation in mice with autoimmune chronic diseases such as arthritis and ulcerative colitis. It also reduces inflammatory responses in asthma.5 A high consumption of kumquat fruit may play a huge role in reducing the production of free radicals and combating some chronic inflammatory conditions as well as some autoimmune diseases.
- Helps in weight management:
As a rich source of dietary soluble fibre, eating kumquat fruit is great for managing your weight and preventing obesity. Their slow movement through the gut allows you to feel full, thereby reducing your appetite and preventing overfeeding. Furthermore, poncirin, one of the flavonoids found in kumquat, has been shown to contribute to weight management by blocking the pancreatic enzyme responsible for digesting fat in the gut. Pocirin also stops fat cells from maturing and increases PPAR-a, a protein that assists in lipid metabolism.6
- Promotes skin health:
Kumquat is a good source of vitamin C, which is a major antioxidant. Antioxidants work to destroy harmful free radicals that have a negative effect on our skin. The effect of these free radicals ranges from fine lines and wrinkles to saggy and blemished skin. Eating a good amount of kumquat will help to reduce the amount of damage caused by these free radicals and stress. They also increase collagen production that ensure your skin stays firm, wrinkle-free and radiant.12 Also, kumquat peels have been discovered by scientists to possess a tyrosine inhibition effect (responsible for preventing skin discolouration), which plays an anti-ageing role. Hence, if you want to have glowing skin, kumquat is a good option to include in your diet.
- Improves bone health:
In order to develop strong bones and stay healthy, you need an adequate intake of dietary calcium. Kumquat contains a good amount of calcium, which is essential for bone formation. Eating kumquats will help strengthen your bones, increase your bone density and reduce your risk of sustaining a fracture. Its vitamin C content also plays a vital role in maintaining healthy bones.
- Healthy eyes:
Some compounds in kumquat such as vitamin A and its precursor, beta carotene, have been found to contribute to healthy eyesight. Our eyes contain rhodopsin, a protein responsible for converting light into an electric signal, which makes it possible for us to see at night. Vitamin A is essential for the production of rhodopsin and helps prevent night blindness7, while beta-carotene fights oxidative stress in macular cells and prevents macular degeneration.
- Gallstone prevention:
People with gallstones are usually encouraged to add a lot of fruits and vegetables to their diet, especially citrus fruits. Some compounds found in them, such as ascorbic acid and limonene, have been discovered to help in the management of gallstones. In a study carried out on a female patient with gallstones, ascorbic acid was found to be a useful therapeutic agent.13
Ripe kumquats are remarkably rich in vitamin C, antioxidants and dietary fibre. A 100g serving of kumquats comprises the following:
- Calories: 71kcals
- Carbohydrates: 15.9g
- Proteins: 1.88g
- Fats: 0.86g
- Water: 81g
- Fibre: 6.5g
- Vitamin A: 290 IU (10% of recommended daily nutritional value)
- Vitamin C: 43.9mg (73% of recommended daily value)
- Riboflavin: 0.009mg (8% of RDV)
- Choline: 8.4mg (2% of RDV)
- Calcium: 62mg (6% of RDV)
- Magnesium: 20mg (6% of RDV)
- Iron: 0.87mg (7% of RDV)
- Zinc: 0.17mg (2% of RDV)
- Manganese: 0.13mg (6% of RDV)
To achieve the nutritional value of 100g serving of kumquats, roughly 4 to 5 kumquat fruits are required.
Side effects and other concerns
Just as with every other food that is consumed in excess, kumquats have a few side effects when you overeat them. This is often due to its high fibre content, which can cause gastrointestinal issues such as flatulence, bloating and abdominal cramps. It is best to avoid any fruit that is discoloured, mushy and unfresh. You can store them in the refrigerator for as long as 2 weeks and in the freezer for as long as 6 months to keep them fresh.
Also, eating your kumquats without properly washing them can cause gut infections as a result of some bacteria that can be found on the surface of the fruit. People who are allergic to citrus fruits may also develop allergies such as swelling, rashes and itching when they eat kumquat fruit.
Kumquat fruit is a highly nutritious fruit unique for its oval shape and sweet, edible peel. It is rich in antioxidants as well as other compounds that contribute to reducing blood sugar, improving skin, bone and eye health, and boosting immunity. Its anti-microbial and anti-cancer properties make kumquat a useful addition to your diet. Due to their anti-inflammatory properties, kumquats can be used in the production of essential oil that relieves arthritis pain as well as boosts skin texture. Aside from eating it whole, you can make kumquat into jams to be used as spreads, bake them into cakes, jellies or add them to your salad.
- Kumquat. [Internet] [Cited 3rd July 2023] Available from: https://gardeningsolutions.ifas.ufl.edu/plants/edibles/fruits/kumquat.html
- Varieties of kumquats, hybrids - Los Angeles Times. [Internet] [Cited 3rd July 2023] Available from: https://www.latimes.com/style/la-fow-kumquatside25-2009feb25-story.html
- Jayaprakasha GK, Murthy KC, Etlinger M, Mantur SM, Patil BS. Radical scavenging capacities and inhibition of human prostate (LNCaP) cell proliferation by Fortunella margarita. Food chemistry. 2012 Mar 1;131(1):184-91.
- Jilie L. Effect of kumquat flavone on blood glucose in mice. PHARMACOLOGY AND CLINICS OF CHINESE MATERIA MEDICA. 2007;23(3):42.
- Huang WC, Lai CL, Liang YT, Hung HC, Liu HC, Liou CJ. Phloretin attenuates LPS-induced acute lung injury in mice via modulation of the NF-κB and MAPK pathways. International immunopharmacology. 2016 Nov 1;40:98-105.
- Zeng H, Miao S, Zhang Y, Lin S, Jian Y, Tian Y, Zheng B. Isolation, preliminary structural characterization and hypolipidemic effect of polysaccharide fractions from Fortunella margarita (Lour.) Swingle. Food Hydrocolloids. 2016 Jan 1;52:126-36.
- The Mechanism for Vitamin A Improvements in Night Vision. [Internet] [Cited 3rd July 2023] Available from: https://www.ebmconsult.com/articles/vitamin-a-eye-vision-mechanism
- Tan S, Li M, Ding X, Fan S, Guo L, Gu M, et al. Effects of Fortunella margarita Fruit Extract on Metabolic Disorders in High-Fat Diet-Induced Obese C57BL/6 Mice. Miele C, editor. PLoS ONE. 2014 Apr 4;9(4):e93510.
- Sung B, Chung HY, Kim ND. Role of Apigenin in Cancer Prevention via the Induction of Apoptosis and Autophagy. Journal of Cancer Prevention. 2016 Dec 30;21(4):216–26.
- Ho CT. Phenolic Compounds in Food. ACS Symposium Series. 1992 Jul 23;2–7.
- Terao R, Murata A, Sugamoto K, Watanabe T, Nagahama K, Nakahara K, et al. Immunostimulatory effect of kumquat (Fortunella crassifolia) and its constituents, β-cryptoxanthin andR-limonene. Food & Function. 2019;10(1):38–48.
- Wu M, Crane JS. Biochemistry, Collagen Synthesis [Internet]. Nih.gov. StatPearls Publishing; 2019. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507709/
- Chekroune M, Benamara S. Gallstones-dissolving capacity of lemon ( Citrus limon ) juice, Herniaria hirsuta L. extract and lemon juice-based natural vinaigrette in vitro [Internet]. Semantic Scholar. 2017 [cited 2023 Sep 1]. Available from: https://www.semanticscholar.org/paper/Gallstones-dissolving-capacity-of-lemon-(-Citrus-)-Chekroune-Benamara/9db848672eda1abc329dc88f73dcc78332f710e