“There was a sheep on the grassland, and suddenly a wolf came”, guess a fruit.
The answer is: Carambola (Sheep Escape)
Carambola is a tropical fruit that is common in Southeast Asia and Lingnan, but relatively rare in the north, and is eaten less often. Many people may have learned about carambola from the elementary school Chinese textbook “Drawing Carambola”.
Carambola, also known as pentagonal fruit, pentagonal fruit, etc., is named for its unique pentagonal cross-section and is called “star fruit” abroad. It has a unique shape and tastes sweet and sour. It can be eaten directly or made into juice or jam.
So what nutrients does carambola have? What should we pay attention to when eating it?
Low in calories and sugar
Compared with other tropical fruits, carambola is not high in calories and sugar. If you want to lose weight, carambola is a good fruit. Carambola has only 31kcal per 100g, which is lower than plums (38kcal/100g) and peaches (42kcal/100g).
The carbohydrate content is even lower, only 7.4g in 100g. In addition to sugar, there is also some dietary fiber. According to the data from the United States Department of Agriculture, the sugar content in carambola is only about 4%.
Data source: Food Composition Table (6th Edition/Standard Edition)
In addition, some foreign literature points out that carambola has strong antioxidant and anti-inflammatory capabilities and is also beneficial to the stability of blood sugar. In China, carambola polysaccharides are the most studied. Similar to other oat glucans and polysaccharides from fungi and algae, carambola polysaccharides have certain effects on immune regulation, anti-tumor, and lowering blood sugar and blood lipids.
However, the existing research data on carambola polysaccharides mostly focuses on how to effectively extract them. However, the research results on the content and specific structure of carambola polysaccharides are relatively limited, and there is relatively little understanding of this aspect. Therefore, we cannot expect to achieve these effects by eating carambola.
Try this, star fruit is more delicious
Star fruit has a unique taste, sweet and sour, with a unique aroma. However, people often have different opinions about the taste of star fruit. Some people think it is sweet and crispy, while more people complain that it is sour and difficult to swallow.
This difference mainly comes from factors such as the maturity and variety of the carambola.
1. Maturity
Unripe carambolas contain higher levels of organic acids and oxalic acid, so they naturally taste sour and astringent. If you buy the kind that is slightly green, let it ripen at room temperature, turning it occasionally, until it turns yellow and emits a fragrant “aroma”.
But if it is allowed to over-ripen, it will turn yellow or even have some brown spots, the taste will become bland and the texture will become limp.
When purchasing, choose carambolas with yellow skin and slightly brown ridges at the five corners, which means the carambolas are just the right ripeness.
2. Variety differences
Different varieties of carambolas also vary in taste and sweetness. There are two main types of carambolas: slightly sour and very sweet. The very sweet variety is naturally sweet and suitable for direct consumption, while the slightly sour variety may be more sour and astringent, making it more suitable for processing into drinks or desserts.
To make carambola more delicious, you can try the following methods:
● Processing: When eating, cut off the head, tail and spine to remove the parts that are most likely to have a bitter taste.
● Seasoning: Slice the carambola and sprinkle it with chili pepper, salt or sour plum powder before eating, or squeeze it into juice and add honey for seasoning, which can effectively improve the taste. For example, the chili powder mixed fruit sold on the streets of southern regions such as Guangxi and Yunnan is made in this way.
● Food combination: Eating star fruit with other sweet fruits or ingredients, such as making star fruit salad or sweet soup, can also neutralize its sour taste.
● As a cooking ingredient: Some friends use carambola when cooking fish or stewing meat.
Is carambola poisonous and inedible? These are the people you should really watch out for!
For friends who like to eat carambola, although carambola is good, they should also pay attention to two “uneasy” ingredients in carambola: carambola toxin and oxalic acid.
So can eating carambolas really cause poisoning? Let me first state the point: healthy people don’t need to worry.
1. Carambotoxin
Carambotoxin is actually a special amino acid named Caramboxin. Its structure is similar to phenylalanine and can directly stimulate the nerve cells in our brain.
What’s more serious is that carambola toxin can make the glutamate receptors in the brain become particularly active, which can cause the nerves to become extremely excited and even cause convulsions, and may cause damage to the nerves in the long run.
For healthy adults, small amounts of toxins can be excreted through the kidneys. However, for people with kidney disease, due to impaired kidney function, these toxins cannot be excreted and will accumulate in the body. Mild poisoning manifests as hiccups, vomiting, confusion, and epilepsy, but in severe cases it can even lead to death.
2. Oxalic acid
In general, fruits are low in oxalic acid (total oxalic acid content <30mg/100g). However, carambolas contain high oxalic acid content, more than 100mg per 100g, especially in low-acid varieties and unripe carambolas.
Image source: Zhong Yun et al. Study on quality analysis and oxalic acid content determination of different carambola varieties
When kidney disease patients consume too much oxalic acid, the kidneys cannot effectively remove oxalic acid from the body due to impaired filtration function. Oxalic acid accumulates in the blood and combines with calcium to form calcium oxalate crystals, which may deposit in the kidneys to form stones or block the renal tubules, further impairing kidney function and even leading to acute renal failure.
Some high-content even half a carambola can cause poisoning, and symptoms of poisoning may appear in as fast as half an hour. Therefore, it is not recommended to consume large amounts of carambola or carambola juice on an empty stomach, even for people with normal kidney function.
Based on the above two reasons, the recommendations for eating carambola are different for different groups of people.
Healthy adults:Be sure to choose sweet carambolas that are ripe, and do not eat more than 2 carambolas a day. Do not eat carambolas (products) on an empty stomach or when you are dehydrated.
Special Populations:If you have any of these conditions, please do not eat carambolas or carambolas products (dried carambolas, carambolas juice, carambolas wine, etc.), as they may cause allergies or poisoning:
1. Kidney disease patients with impaired kidney function
2. Infants and the elderly with imperfect renal function
3. People who are allergic to carambola may experience itching and rashes after eating carambola
4. People who are taking certain medications. If you are taking drugs such as Bosutinib, Panobinostat, and Venetoclax, you must avoid carambolas.
In short, patients with kidney disease, especially those with renal insufficiency, should not eat carambola or carambola products. For healthy people, there is no need to worry, but they should be eaten in moderation.
references
[1]ZHU Yin-ling, TAN Zhu-jun, ZHU Yin-ling, et al. Purification and identification of polysaccharide components from carambola[J]. Modern Food Science and Technology, 2008, 24(2):4.DOI:10.3969/j.issn.1673-9078.2008.02.017.
[2]Yang Yuexin. Chinese Food Composition Tables 6th Edition Volume 1 and 2[M].Peking University Medical Press, 2018.
[3]Chinese Nutrition Society. Encyclopedia of Chinese Nutrition Science (2019). Beijing: People's Medical Publishing House, 2019.
[4]Zhu Yinling, Tan Zhujun, Li Weicai, et al. Study on the extraction of carambola polysaccharides[J]. Food Industry Science and Technology, 2008(3):3.DOI:CNKI:SUN:SPKJ.0.2008-03-039.
[5]wikipedia.Carambola.https://en.wikipedia.org/wiki/Carambola
[6]WebMD.Star Fruit: Nutrition and Health Benefits.https://www.webmd.com/diet/star-fruit
[7]Muthu N, Lee SY, Phua KK, Bhore SJ. Nutritional, Medicinal and Toxicological Attributes of Star-Fruits (Averrhoa carambola L.): A Review. Bioinformation. 2016 Dec 22;12(12):420-424. doi: 10.6026 /97320630012420. PMID: 28405126; PMCID: PMC5357571.
[8]Zhong Yun, Jiang Bo, Jiang Nonghui, et al. Study on quality analysis and oxalic acid content determination of different carambola varieties[J].Guangdong Agricultural Science, 2009(12):3.DOI:10.3969/j.issn.1004-874X.2009.12.024.
[9]Salgado N, Silva MA, Figueira ME, Costa HS, Albuquerque TG. Oxalate in Foods: Extraction Conditions, Analytical Methods, Occurrence, and Health Implications. Foods. 2023 Aug 25;12(17):3201. doi: 10.3390/foods12173201. PMID: 37685134; PMCID: PMC10486698.