But first, what are they?
Let us begin by asking, what are kumquats? Well, they look like little oval oranges, but their polyphenols (magical plant properties including flavonoids, phenolic acids and lignans) are very different compared to other citrus fruits. They are an Asian fruit, with a mouth-puckering tart flesh and a sweet, edible exterior. You can pop the entire thing in your mouth.
Kumquats are a little elusive because they are not a New World fruit, but that doesn’t mean they don’t thrive here. I discovered them because my home had a mature kumquat tree in the backyard. My kids loved them immediately, but I was not quite sure what to do with them. Now, I slice them onto Greek yogurt, cottage cheese, salads, or I use them as a natural sweet-and-sour addition to my Indian and Asian dishes.
Once I started eating kumquats daily (yes, I am eating them now), I wanted to know more about what I was feeding my body. Of course, kumquats are fruits, so I knew they would be good for me, but given that I eat their peel, I was curious about what secrets were stored inside. This is what I found:
Fiber
Fiber is essential for our gut bacteria. It is the prebiotic food that feeds our probiotics (gut bacteria). The USDA recommends somewhere between 14 and 34 grams of fiber, depending on age (see table below). For any of you who pay attention to fiber intake, you know how challenging it is for the average person to meet their needs. For those who consume plenty of beans and lentils, this is more feasible, since a serving of legumes may contain as much as 12 grams of fiber!
Let’s bring the conversation back to kumquats. Kumquats, for as tiny as they are, are packed with fiber. Nearly 6% of their weight is fiber. That means for every 100 g serving– 9 kumquats, based on my scale– you are getting about 5.7 g of fiber. The USDA actually calculates it out to 6.5 g of fiber. Either way, this is a lot of fiber. For comparison:
- 6.5 g fiber/100 g kumquats
- 1.7 g fiber/100 g strawberries
- 1.8 g fiber/100g unpeeled Honeycrisp apple
- 2.4 g fiber/100 g orange*
Antioxidant and antimicrobial properties
I did not realize that kumquats and citrus fruits were used in traditional Chinese medicine. Often, the peels are dried or heated and used for respiratory infection treatment. Because kumquats are eaten along with the peel, I did a little search on what is known.
Relative to other fruits, there is very little research on kumquats. I did find some in vitro studies (in labs, not on animals or humans) that suggested the peel, more so than the flesh, has strong antioxidants properties, and these compounds are unique relative to other citrus fruits. Another in vitro study demonstrated inhibition of food-borne bacteria using essential oils extracted from kumquat peels. There is also some anti-cancer research looking at prostate cancer cells and their reduced growth in the presence of kumquat compounds.
I did find a human, observational study looking at cough duration in patients with non-severe COVID-19 in 2023. There were about 200 participants in each group and, on day 7, the group receiving the kumquot mixture had a 93% resolution in cough symptoms vs. 40% in the untreated group. This was not a blinded or controlled study, but it is nonetheless interesting, especially given the safety of the intervention. There were no significant adverse effects.
Metabolic Benefits
A mouse study compared three groups of mice: those fed standard chow, a high fat diet or a high fat diet plus kumquat extract. The mice given the kumquat extract had lower glucose levels, better glucose tolerance tests, and a better cholesterol profile. Call me up if you are interested in doing a human trial on kumquats!
Bite Sized Message: Kumquats are A-peeling
Sorry. I couldn’t resist.
Look for kumquats in your local grocery stores, instacart or farmers markets. Like I mentioned above, I love to slice them into salads, yogurt or cottage cheese while my kids love the zing of eating them whole. We also cut them in half and freeze them for a quick, healthy popsicle-like treat.
*100 g of strawberries is about 6 medium strawberries and 33 calories. 100 g of apple is about ¾ of a medium sized apple and 53 calories. 100 g of orange is 47 calories and about half of a peeled orange. 100 g of kumquats is about 71 calories and about 9 kumquats. I weighed the fruit on my calibrated home scale. Fiber content based on USDA sources listed below and Dietary fiber content and composition of fruits in Taiwan.
If you found this helpful or educational, please share, follow on your preferred platform or subscribe below. For coaching or consultations, please contact me at www.DrAngel.com.
References:
USDA. “Dietary Guidelines for Americans, 2020-2025.” U.S. Department of Agriculture, 2020, pp. 144–145.
https://fdc.nal.usda.gov/food-details/168154/nutrients (kumquat details USDA)
111895 – Apples, Honeycrisp, Fresh
https://fdc.nal.usda.gov/food-details/169097/nutrients (orange details USDA)
Chang, S C et al. “Dietary fiber content and composition of fruits in Taiwan.” Asia Pacific journal of clinical nutrition vol. 7,3/4 (1998): 206-10.Dietary fiber content and composition of fruits in Taiwan
Lou, Shyi-Neng, and Chi-Tang Ho. “Phenolic compounds and biological activities of small-size citrus: Kumquat and calamondin.” Journal of food and drug analysis vol. 25,1 (2017): 162-175. doi:10.1016/j.jfda.2016.10.024
Wang, Yong-Wei et al. “Chemical composition and antimicrobial activity of the essential oil of kumquat (Fortunella crassifolia Swingle) peel.” International journal of molecular sciences vol. 13,3 (2012): 3382-3393. doi:10.3390/ijms13033382
Jayaprakasha, G.K., K.N. Murthy, M. Etlinger, S.M. Mantur, and B.S. Patil. “Radical scavenging capacities and inhibition of human prostate (LNCaP) cell proliferation by Fortunella margarita.” Food Chemistry, vol. 131, no. 1, 1 March 2012, pp. 184-191.
Hua, Qiaoli et al. “Effectiveness of kumquat decoction for the improvement of cough caused by SARS-CoV-2 Omicron variants, a multicentre, prospective observational study.” Phytomedicine : international journal of phytotherapy and phytopharmacology vol. 120 (2023): 155008. doi:10.1016/j.phymed.2023.155008
Tan, Si et al. “Effects of Fortunella margarita fruit extract on metabolic disorders in high-fat diet-induced obese C57BL/6 mice.” PloS one vol. 9,4 e93510. 4 Apr. 2014, doi:10.1371/journal.pone.0093510
