Karonda benefits and side effects

In a study at Nagpur University, Prakash R. Itankar tested whether the extract of unripe Karonda fruit could reduce blood sugar in lab mice that had been given alloxan to induce diabetes.

The researchers reported that depending on whether it was a methanol extract or an ethyl acetate soluble fraction, at a dose level of 400 mg per kilogram of mouse weight karonda fruit extract reduced blood glucose levels in mice by 48% or 64.5%, respectively, compared with diabetic mice that were not given karonda fruit extract.

The scientists attributed this effect to the polyphenolic and flavonoid compounds present in karonda fruit.

(Read more: Diabetes diet)

Another animal study on the effect of methanolic extract of karonda fruit for diabetic nephropathy found that it increased antioxidant activity in the kidney, thereby reducing oxidative stress and biomarkers of nephrotoxicity (kidney damage) in the blood and urine. From this, the researchers surmised that 200-400 mg per kilogram of weight given to Sprague Dawley rats (injected with gentamicin antibiotic to create nephrotoxic conditions) over eight days exerted a protective influence over the kidneys. The research was published in the Journal of Acute Disease in 2015.

(Read more: Exercises for Diabetes)

Another study on the effects of the leaf extract of karonda and ramphal (Annona reticulata L. or bullock’s heart fruit) on lab mice found that:

• Karonda leaf extract nearly halved artificially increased blood glucose in mice when given at 400 mg per kilogram of mouse weight
• Ramphal leaf extract achieved similar results at 200 mg per kilogram.

It is important to note that much more research (including human clinical trials) is needed to confirm the effects of the leaves and fruit of these plants in humans. The authors of this study admitted as much when they wrote: "However, the exact mechanism of reduction in the concentration of serum glucose remains to be elucidated. The antihyperglycemic activity of extracts of leaves from both plants (Carissa carandas L. and Annona reticulata L.) suggests that further scientific studies need to be conducted towards the discovery of possible new antidiabetic compounds.”

(Read more: Ayurvedic herbs for diabetes)

A study published in the Asian Journal of Pharmaceutical and Clinical Research in 2015 states that karonda has been used to treat digestive issues like constipation and diarrhoea for many years in India as per Ayurvedic, Unani and Homeopathic systems of medicine. Modern medicine and research prove these benefits, crediting them to the presence of phytonutrients like alkaloids, flavonoids, saponins, glycosides, triterpenoids, phenolic compounds and tannins. Another study published in the journal J Ethnopharmacol in 2011 also says that karonda may help improve digestion and may also be used as a medication against intestinal worms due to its anthelmintic and antimicrobial properties.

Current research shows that karonda has analgesic properties which ensure that it can aid in pain relief. A study published in the journal Natural Products and Bioprospecting in 2017 suggests dose-specific consumption of the extract of the wild species of karonda, Carissa spinarum, may help manage chronic joint pain associated with rheumatoid arthritis and arthritis. Another study, also published in 2017 in the journal Medicines, shows that consuming karonda extract may help relieve muscle pain and fever due to pain. However, the dosage of the extract required to manage pain should be decided by a naturopathic doctor.

(Read more: Homeopathic treatment for joint pain)

A 2009 study with Swiss mice in a lab found that an ethanolic extract of the root of karonda plant could:

• Reduce the duration of a seizure induced by maximal electroshock in mice when it is administered at 100-400 mg per kilogram weight
• At 200 mg/kg and 400 mg/kg, this extract could provide some protection against seizures
• These dosages also delayed the onset (latency) of chemically induced seizures in mice

The researchers also found that the crude extract of karonda root contains “small quantities of alkaloids, flavonoids, saponins and large amounts of cardiac glycosides, triterpenoids, phenolic compounds and tannins”. These are all plant compounds, and many of them have been separately shown to have antioxidant or antimicrobial properties.

Another study on the anticonvulsant and sedative effects of karonda focused on the leaves of the plant—it suggested that an extract of karonda leaves may be used in the treatment of epilepsy. The researchers found alkaloids, glycoside, tannins and terpins in the leaf extracts, and found that the extract could offer some protection against chemically induced seizures in mice at about 400 mg/kg. They also said that at this dosage, the extract could help reduce two of the symptoms of seizures: extensor (in which the muscles extend and tense up; for example, a pronounced arching of the back for several seconds) and stupor.

Many more studies need to be done to confirm or deny any benefits of karonda roots or leaves for seizures including epilepsy seizures, as this seems to be an under-researched area.

(Read more: Ayurvedic treatment for epilepsy)

Studies show that consuming karonda extract may have hepatoprotective effects, meaning that it can prevent liver damage and keep this vital organ healthy too. One particular study published in the Indian Journal of Experimental Biology in 2009 explains that extract of the roots of Carissa carandas protects the liver against toxicity and inflammation by reducing the activities of liver enzymes and bilirubin and the oxidation of lipids. At the same time, this extract can significantly increase the levels of uric acid, glutathione, superoxide dismutase, catalase and protein in such a way that the weight of the liver is well maintained and the risk of liver disease is significantly reduced. This evidence also supports the role played by karonda in liver health as indicated in Ayurvedic texts.

Ayurveda supports the use of karonda in treating, as well as preventing, skin infections and skin diseases. A study published in BioMed Research International in 2014 reveals that consuming the dried fruits of Carissa carandas can reduce skin inflammation and prevent skin rashes and infections. Another study published in the Journal of Pharmacy and Pharmacology in 2020 says that karonda contains a wide variety of flavonoids, phenolic acids, steroids, volatile oils, lignans, alkaloids and other phytonutrients that provide it with antioxidant, anti-inflammatory, antimicrobial and antifungal properties. This suggests that consuming dried or juiced karonda can prevent fungal infections and bacterial infections associated with the skin. Although there is only limited research currently, some studies also suggest that karonda may help manage skin disorders such as eczema and psoriasis.