Carambola (Star Fruit) – Averrhoa Carambola

Carambola fruit is a unique fruit because of its star-like shape and attractive flavor. Carambola is commonly known as star fruit and KUMRAKH in Hindi. Since a long time, it has been used as a traditional medicine in Brazil. Carambola fruit juice or tea prepared from carambola leaves are extensively used to lower high blood sugar levels and high blood pressure. It also stimulates the appetite and has anti-diarrheal effects. Carambola leaf extract also possesses heart-protective effect. Some studies have even found that carambola fruit has a life-threatening effect on people with kidney diseases. Some negative effects on the brain of such patients have also been discovered.

Health Benefits of Carambola (Star Fruit)

Leaves of carambola are anti-pyretic (treats fever or lowers body temperature), antipruritic (reduces itching) and anthelmintic (expels parasites out of the body). It is also useful in the treatment of scabies, different types of poisoning, fractured bones, intestinal worms and fever. In Brazil, carambola leaves are used for lowering high blood sugar levels. In India, to counteract fever, ripe carambola or its juice is used. The fruits are also used for the treatment of vomiting, diarrhea, hemorrhoids, acidity and piles.

Overall Nutrient Composition of Carambola

Carambola fruit contains a number of health promoting compounds such as flavonoids, alkaloids, tannins and saponins. In addition to this, the fruit also contains GALLIC ACID, ASCORBIC ACID, PROANTHOCYANIDINS and EPICATECHIN. Edible portion of carambola fruit is a good source of minerals, dietary fiber and antioxidants.

Carambola is an excellent source of natural antioxidants that helps to reduce oxidative stress. It is low in calories and a good source of minerals such as calcium, iron, phosphorus and potassium. It also contains carotenoids, thiamine (vitamin B1) and riboflavin (vitamin B2) and vitamin C.

Extremely Rich in Antioxidants

Important antioxidants present in carambola include:


Low concentration of antioxidants in the body increases the level of oxidative stress, which further causes damage to the body. Carambola fruits, leaves as well as bark are rich sources of antioxidants. Carambola contains phenolic compounds and flavonoids that possess strong antioxidant and radical scavenging properties. It is very well recognized that foods with antioxidant content have a beneficial effect on the body.

Antioxidants present in carambola can prevent or delay oxidative damage to lipids and proteins caused by free radicals. An interesting study observed that carambola fruit has high antioxidant level, which is similar to banana, guava and papaya. With ripening, the antioxidant capacities of carambola fruit increased significantly. The antioxidant content of ripe carambola fruit pulp was 3.3 times higher than unripe fruit pulp. PROANTHOCYANIDINS present in carambola fruit is a strong antioxidant that protects against free radical damage. EPICATECHIN, a health-promoting compound present in carambola fruit, stabilizes the free radicals and suppresses its harmful action.

The study further found that carambola fruit peel exhibits high antioxidant capacity than pulp. Therefore, it is important to eat whole carambola fruit in order to get a higher dose of antioxidants.

Abundant In Phytochemicals

Phytochemicals are health-promoting compounds that are present in plants. Research has found that carambola is abundant in these healthy compounds. The most important phytochemicals present in carambola include:


These phytochemicals exhibit strong antioxidant properties too. Studies have shown that phytochemicals protect the body against various harmful diseases and disorders such as high blood sugar levels or hyperglycemia, cancer, cataract, cardiovascular diseases, arthritis and inflammatory diseases.

Therapeutic Advantages

Many studies claim that carambola fruit (starfruit) as well as its other plant parts have been used as a folk medicine. Such a therapeutic potential of carambola is due to the presence of various health promoting compounds in it. Let’s have a look at how carambola plays an important role in the treatment and prevention of various diseases:

Type 2 Diabetes Mellitus

Since a very long time, in Chinese culture, the roots of carambola have been used to treat diabetes. Such anti-diabetic or hypoglycemic effect of carambola is due to its potent pharmaceutical activities. Treatment with carambola root extract lowered high blood sugar levels and protected the pancreatic beta cells against death. It reduces high fasting blood sugar levels, reduces the production of glucose by the liver and increases the uptake of glucose by the muscles. Hence, more glucose is used as a source of energy and less is present in the blood.

Carambola fruit also contains high amount of insoluble dietary fiber (a part of plant that is not digested by humans). The presence of this, fiber helps to control blood sugar levels after meals. Flavonoids present in carambola serve as natural agents for diabetes control. Thus, carambola fruit, its plant’s leaves, healthy plants compounds present in them help in the management of type 2 diabetes mellitus.

High dietary fiber contents slow down the release of glucose from starch upon digestion. It also inhibits the enzyme that converts starch into glucose during the process of digestion. Therefore, it can be suggested that carambola can be added to diabetic diet to help control blood sugar concentration.

High Cholesterol Level

Research has shown that carambola has hypolipidemic effect and it prevents the development of non-alcoholic fatty liver disease. It was observed that treatment with carambola lowered the level of total cholesterol and triglyceride. Such effect was due to high content of dietary fiber. High dietary fiber levels present in carambola increased the excretion of total fat, cholesterol and bile acids. In addition to this, carambola contains PHYTOSTEROLS that help in lowering high cholesterol levels.

PHYTOSTEROLS are health-promoting agents that are obtained from plants. These sterols are similar to cholesterol and it occurs in plants only. Many studies have claimed that phytosterols reduce the level of LDL- low-density lipoprotein cholesterol (unhealthy) and thus, reduces the overall risk of cardiovascular diseases. Phytosterols compete with cholesterol absorption in gut. They replace cholesterol and thus increase its excretion.

Another research showed that health promoting compounds present in carambola fruit such as phytochemicals, flavonoids, Phytosterols, saponins, ascorbic acid and dietary fiber either increase the use of fat as a source of energy or increase excretion of excess cholesterol out of the body or thus, reduces its storage in the body in the form of cholesterol. Thus, carambola fruit can be made an important part of cholesterol lowering diet.

Pain Reliever

Scientific studies have found that carambola has analgesic property and it helps to relieve pain. Carambola’s extract works by suppressing the formation of pain mediators in the tissues. It also inhibits pro-inflammatory markers that increase the pain. Furthermore, research has also shown that carambola extracts act similar to MORPHINE, a drug used to relieve pain. Thus, carambola extracts can be used to treat painful inflammatory diseases. However, more studies are required to find out the efficacy of carambola.

High Blood Pressure

A direct positive link is found between high blood pressure and the risk of cardiovascular diseases. Research found that carambola leaf extract inhibits the contraction of blood vessels and prevents rise in the blood pressure. On the other hand, carambola extract also widens the blood vessels, which ensures smooth blood flow all throughout the body. Various flavonoids have also been identified in carambola fruit that have blood pressure-lowering effect. Thus, carambola leaf can be used in the treatment of high blood pressure.

Also Read: Ayurvedic Medicine for High Blood Pressure

Antimicrobial Properties

Research has found that carambola exhibits anti-microbial, anti-bacterial and anti-fungal properties. Green or unripe carambola fruit has a higher ability to inhibit microbes as compared to ripe or mature carambola fruits. Carambola leaves also possess anti-microbial activity against gram-positive and gram-negative bacteria. A comparative study showed that carambola leaf extract had higher anti-microbial and anti-bacterial activity as compared to passion fruit and papaya leaf extract. Furthermore, the effect of carambola leaf extract was also compared to streptomycin, a drug used to inhibit the action of bacteria. It was found that the anti-bacterial activity of carambola leaf extract was higher than streptomycin drug. Besides this, carambola bark also has the ability to kill some of the bacteria.

An interesting research showed that carambola plant extract showed anti-bacterial activity against –

  1. typhi
  2. coli
  3. aeruginosa
  4. megateriu

Such an inhibitory effect against various bacteria is due to the presence of phytochemicals such as flavonoids, alkaloid, saponins and steroids.

Antidotal Effect

Antidotal means a medicine or a remedy, which is used to counteract the harmful effects on overall health. Toxic agents enter the body and affect the metabolism of carbohydrate, protein and fat. Such alteration in the metabolism may further induce high blood glucose and high cholesterol levels. An interesting research showed that supplementing the diet with carambola powder helped to normalize blood glucose and total cholesterol levels. Such beneficial effect of carambola was due to the presence of PHENOLIC ACIDS, ANTIOXIDANTS, SAPONINS, PHYTOSTEROLS and FLAVONOIDS. Carambola powder increased the excretion of toxins and thus, helped to reduce the harmful effects, which were caused by toxin overload. Higher the dose of carambola powder greater was the positive and beneficial effect on the body.

A link was also found between excess toxin overload and increase in the levels of oxidative stress. These harmful toxins lower the level of antioxidants and in turn raise the level of oxidative stress. It is very well known that carambola is an abundant source of natural antioxidants. These antioxidants reduce oxidative stress and increase the activity of antioxidant enzymes in the body. Therefore, it can be concluded that carambola powder (supplement) is very effective in the treatment of diabetes mellitus, altered lipid profile and diseases and disorders associated with high level of oxidative stress.


Carambola plays a very important role in improving digestion and it keeps many digestive disorders at bay. The presence of health promoting compounds in carambola fruit helps in the treatment of diarrhea, dysentery and vomiting. Ripe carambola fruit also reduces pain and abdominal cramps associated with diarrhea. Research showed that decoction of carambola leaves can be used to treat inflammation of the inner lining of the stomach. Carambola leaves increase the excretion of toxins and bacteria that cause inflammation of stomach and intestines. It also relieves bleeding hemorrhoids. Carambola also serves as a digestive tonic and improves the overall digestion. Thus, in simple words, it can be concluded that ripe carambola fruit and leaves are gut-friendly and they keep digestive disorders at bay.

Gastric Ulcer

Many studies have claimed that carambola leaves possess anti-ulcer activity. Carambola leaf extract inhibited excess gastric acid secretion, which causes damage to the inner lining of the gut. It further increased the mucus production, a viscous substance that protects the inner lining of the stomach against harmful effects of acid. Furthermore, it reduced the pro-inflammatory markers and overall inflammation and maintained the cellular integrity of stomach lining. Carambola leaves also increased the production of bicarbonate that further helped to neutralize the effect of acid and protected against gastric lesions and ulcers. Such anti-ulcer effect of carambola is due to the presence of TRITERPENES and FLAVONOIDS. These compounds prevent contact between the inner lining of the stomach and necrotizing agents. Thus, carambola leaves are very useful in the treatment of stomach and duodenal (part of intestine) ulcers.


An overload of reactive oxygen species plays an important role in cancer. Reactive oxygen species promote the formation of tumor and this further increases the spread of cancer to other parts of the body. Therefore, foods rich in antioxidants, which can scavenge these reactive oxygen species and lower the level of oxidative stress, are required for the treatment of cancer. Carambola is one such fruit, which is completely packed with natural antioxidants. A study observed that treatment with carambola increased the level of antioxidant enzymes such as CATALASE, SUPEROXIDE DISMUTASE and GLUTATHIONE. Such increase raised the activity of antioxidants and protected the body against oxidative stress.

Free radicals cause oxidative degradation of fatty acid, which may lead to the production of several toxic products. These toxic products attack the DNA, which may further lead to development of cancer. Carambola is a good source of Phytosterols that inhibits the oxidative degradation of fatty acid. Hence, carambola plays a protective role against cancer.

How to Select & Store Carambola Fruit

As the fruit ripens, it increases in size. Therefore, select a larger fruit with a sweet and sour taste versus a smaller fruit with sour taste.

  1. Make sure that the fruit is free of blemishes, cuts and spots.
  2. Green carambola fruits are sour and acidic whereas, yellow carambola fruits are fully ripe and sweet. As they both have different tastes and flavors, pick accordingly.
  3. Carambola fruit can be stored for a few days at room temperature.
  4. If you want to store them for a long period, store it in a plastic bag and place them in the refrigerator.

Quick Medicinal Uses

  1. Ripe carambola fruit or fruit juice is used to stimulate appetite. It is also used as a laxative, so it helps to relieve constipation.
  2. In lactating mothers, carambola fruit increases lactation and breast milk production.
  3. Crushed leaves are applied externally in the treatment of ringworm and chickenpox.
  4. Decoction of carambola leaves is used to relieve gastritis (inflammation of stomach) and angina (pain in the chest).
  5. Boiled carambola flowers are used in the treatment of malaria and fever. These flowers are also used for the treatment of dermatitis in Southeast Asia.
  6. Carambola roots are used to treat muscle pain and headaches.
  7. Decoction of crushed carambola seeds is used as a galactagogue that is it increases the production of breast milk in lactating mothers.
  8. Powdered seeds are very effective in relieving pain and asthma attacks.
  9. Carambola leaf extract and supplements are also available in the market.

Different Ways to Eat Carambola

  • Carambola fruit can be sliced and eaten or it can be added to salads.
  • Carambola fruit is used in the preparation of tarts and pudding.
  • It can also be added to curries and stews.
  • In Malaya, carambola fruit is commonly stewed with sugar and cloves or alone or in combination with apples.
  • In China, carambola is usually cooked with fish.
  • In Thailand, unripe carambola fruits are sliced and cooked with shrimp.
  • Unripe carambola fruit can also be made into jam, pickles or other types of preserves.
  • Carambola fruit is also cooked as a vegetable in Queensland.
  • A very refreshing sherbet is made out of carambola in Hawaii.
  • Jellies can be prepared with fresh carambola fruit.

Safety Profile

However, Carambola or star fruit is POSSIBLY SAFE to eat in food amounts, but it may have side effects or contraindication in some health condition, as discussed below.

Drugs & Carambola

Anti-diabetic drugs

So far, no interaction has been observed between carambola fruit and a drug. But some source of evidence has shown that carambola leaves and anti-diabetic drug when taken together may lead to hypoglycemia. Carambola leaves are very effective in lowering blood glucose levels. A diabetic individual should not consume both as a part of his/her treatment. If both are taken together, there are high chances that blood glucose levels may fall beyond normal range.

Who Should Avoid Carambola?

Uremic Patients

Uremia is a state in which ‘urea’ a waste product gets accumulated in the blood. Such condition is common in people with kidney disease. A research showed that when carambola was consumed by such patients it gave rise to a number of symptoms such as intractable hiccups, decreased muscle power, vomiting, mental confusion, insomnia (inability to fall asleep at night), limb numbness and seizures. In such patients, dialysis was required for the intoxication of carambola fruit. If these patients are not treated on time, it may even lead to death. Therefore, it is very important that individuals with kidney disease should strictly avoid consuming carambola.


Over-exposure to toxins alters the normal activity of the nervous system and thus, causes damage to the body. Toxins are harmful substances that may come in contact with the body through food, air and water. Consuming foods high in oxalate causes neurotoxicity. Carambola fruit contains high concentration of oxalates. High consumption of carambola suppresses the normal function of a part of brain. It causes some functional as well as structural changes. However, such effects are mainly observed in individuals with kidney diseases. This is because the ability to excrete oxalate is lowered in individuals with kidney diseases. Such a harmful effect is not found in healthy individuals.

About Carambola Plant

Carambola is widely cultivated in Malaysia and Southeast Asia. It is believed that carambola was first cultivated in the Moluccas and Ceylon. Today it is widely cultivated across different parts of the world such as Taiwan, Thailand, Florida, Israel, China, Philippines, Indonesia, Australia, and Bangladesh and in warmer regions of India.

Carambola is a multi-stemmed, small and attractive slow growing tree with a short trunk. It is usually 5 to 7 meters tall and it can be even be 10 meters tall, but it is quite rare. Carambola leaves are oblong in shape and they have a medium-green color. The leaves are 2 to 9 centimeters long and 1 to 4.5 centimeters wide. Carambola’s leaves tend to fold at night and are very reactive to light. Carambola flowers are arranged in small clusters, which have beautiful purple color.

During unripe stage, carambola fruits are green in color and small in size. As they mature, they turn yellow or orange in color and increase in size. Carambola fruits are oblong in shape and they have a length of 15 centimeters and 9 centimeters of width. These fruits are star-shaped when cut in cross section and they have a very crisp texture. The inner flesh is translucent and very juicy. Its taste varies from mildly sweet to very sour.

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Sneha Sadhwani

Dt. Sneha Sadhwani Sewlani (B.Sc. Food Science & Nutrition, PG in Clinical Nutrition & Dietetics) is Clinical Nutritionist & Certified Diabetes Educator and Certified Lifestyle Coach. She has expertise in clinical nutrition and 4 years’ experience working as Clinical Nutritionist and Dietician. She has been associated as a nutritionist with LTMG Hospital and S. L. Raheja Fortis Institute in Mumbai.She has also her own private practice where she offers a wide range of different programs, including weight loss, weight gain, diabetes management, diet plan according to diseases and much more through her in-person and online consultation.Sneha strongly believes that a healthy diet and lifestyle modifications are the best ways to prevent and treat diseases. She says, “Eating healthy is an art, be an artist of your own mind and body”.

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