Category: alternative medicine

Karela (Momordica charantia) and #diabetes

Right let’s see how Posterous manages to muck up my beautiful formatting. I should take a before and after screenshot 😉


I should add that I am not medically trained, the information below may be inaccurate (I wrote it, no-one else) and I really wouldn’t recommend using a non-standardised plant extract to treat a condition as complicated as diabetes. Speak to your doctor first or at least let them know that you are planning on using this. There’s a big difference between eating something as a foodstuff or food flavour and using it pharmacologically (using it at doses where it can have some significant effect on the body).




Karela (Momordica charantia) and diabetes

Karela (Momordica charantia), also known as bitter melon, bitter gourd, balsam pear, cundeamor and ampalaya, is a member of the cucumber family, grown for its edible fruit. Various parts of the plant (fruit, seeds and leaves) have also been used in traditional Asian medicines in the treatment of Type 2 diabetes.


Chemical analysis of karela indicates several compounds with plausible antidiabetic effects which have been demonstrated in cell-based assays. In laboratory tests on muscle and fat cells, karela compounds stimulated the ‘docking’ of a glucose transporter channel to the cell membrane, an essential step in the take-up of glucose. These compounds also stimulate a key biochemical pathway involved in fatty acid oxidation as well as glucose entry into cells (Tan 2008). The compounds may lower glucose levels in the blood via other mechanisms, for example by suppressing the liver???s production of glucose from scratch (Dans 2007).


Several case reports and small studies have demonstrated that using karela can lower blood glucose levels in the short term and improve glucose tolerance. Healthcare professionals should be aware that ‘patients may possibly be using karela as well as more orthodox drugs to control their diabetes’ and that karela can have an additive effect when taken with prescribed medication; this may increase the risk of hypoglycaemia. Additionally ‘irregular consumption of karela as part of the diet could possibly contribute to unexplained fluctuations in diabetic control’ (Aslam 1979, Baxter 2009).


Although karela’s blood glucose lowering capacity is established there is a dearth of evidence from well conducted human studies. One randomised controlled trial (a small pilot study in 40 people with Type 2 diabetes who were either newly diagnosed or had poorly controlled diabetes) compared the effects on HbA1c levels of M. charantia capsules versus inert capsules, over a period of three months. There was a very small effect in favour of the use of karela however the authors acknowledge that the study was insufficiently powerful to detect any significant effects and that ‘the results of this study can be used to estimate the sample size for bigger studies’ (Dans 2007).


In addition to any changes in HbA1c the researchers looked at karela???s effects on fasting blood glucose, serum cholesterol levels and weight. Safety endpoints were also measured including liver enzyme tests however there were no significant differences between the treatment and control group (Dans 2007).


Preparations used

In addition to its culinary use as a vegetable in many Asian dishes it is used therapeutically as dried powdered fruit (eg in capsule form), fried fruit, juice or liquid extracts from the fruit. The leaves are also used to prepare a tea.


Safety risks

Although karela is well tolerated as a foodstuff and is noted for its bitter taste there can be safety issues around using plant material therapeutically. A case study of two young children, who did not have diabetes, reported that they experienced hypoglycaemic coma and seizures after drinking karela tea (Hulin 1988); additionally it is known that the red coating of the seeds is also toxic to children.


Several of the patients in the trial reported gastrointestinal problems with the use of karela, including diarrhoea (Dans 2007).


Karela may interact additively with other diabetes medications increasing the risk of hypoglyclaemia and it may be appropriate to monitor blood glucose levels more frequently in someone using karela alongside prescribed antidiabetic medications (Aslam 1979, Baxter 2009).


Use in women who are pregnant

Animal studies in rabbits indicate that karela juice can cause uterine bleeing in pregnant rats and rabbits (Raman 1996) and the plant has been traditionally used to induce abortion (Grover 2004) therefore it is not recommended for use in pregnant women.


Recommendations for people wishing to use karela

The use of karela in managing diabetes is not currently recommended as there is insufficient data to suggest an appropriate dose and its use may increase the risk of hypoglycaemia when taken with other prescribed diabetes medications. Anyone wishing to try karela should discuss this with their healthcare team.



Aslam M and Stockley IH (1979) Interaction between curry ingredient (karela) and drug (chlorpropamide). Lancet 1 (8116): 607.


Baxter K (2009) Antidiabetics and karela (Momordica charantia) in Stockley’s Drug Interactions [online] London: Pharmaceutical Press. (subscription required) 


Dans AM, Villarruz MV, Jimeno CA et al (2007) The effect of Momordica charantia capsule preparation on glycemic control in Type 2 diabetes mellitus needs further studies. Journal of Clinical Epidemiology. 60 (6): 554-559.


Grover JK and Yadav SP (2004) Pharmacological actions and potential uses of Momordica charantia: a review. Journal of Ethnopharmacology. 93 (1): 123-132.


Hulin A, Wavelet M and Desbordes JM (1988) Intoxication aigu?? par Momordica charantia (sorrossi). A propos de deux cas. Sem Hop Paris 64, 2847???8.


Raman A and Lau C (1996) Anti-diabetic properties and phytochemistry Momordica charantia L. (Cucurbitaceae) Phytomedicine 2: 349-362.


Tan MJ, Ye JM, Turner N et al (2008) Antidiabetic activities of triterpenoids isolated from bitter melon associated with activation of the AMPK pathway. Chemistry & Biology. 15(3): 263-273.

St John’s wort, depression and #diabetes

Am putting together a brief document on the use of St John’s Wort in people who have diabetes and depression. What have I missed? Does anything sound ridiculous, poorly argued or plain ignorant? Rip it to shreds so that it’s better when I share the final version with my colleagues (ie, please do a little bit of my work for me ho ho) 😉

I’ve not found information about any possible effect of SJW on insulin metabolism – I’ve assumed that this is because insulin is largely metabolised by the kidney whereas some of the other diabetes drugs are dealt with more by the liver…?? I might be wrong. I have enough knowledge of pharmacology to be aware of the possibilities but insufficient knowledge to deal with it effectively!


St John???s wort, depression and diabetes

St John’s Wort (Hypericum perforatum) is a flowering herb popularly used in treating depression (Linde 2009). A Cochrane review of 29 trials, with over 5,000 participants, found that extracts of St John’s Wort were more effective than placebo in treating mild to moderate pervasive depression, however the effects are relatively small (Linde 2009). The studies also showed that St John???s wort is similar in effectiveness to antidepressants but has fewer side effects.

The authors of this review concluded that the use of St John???s wort may be justified but only on the advice of a healthcare professional. While side-effects from the plant are minimal there can be problematic interactions with other medications that people may be taking.

People with diabetes are at greater risk of developing depression (Diabetes UK) and they may also be taking medication for other health conditions in addition to any medication for diabetes.

Preparation used

The flowering tops of the plant are used and the resulting extract (which can vary considerably in quality) is sold in tablet or capsule form. The plant contains a variety of bioactive compounds such as hypericin and hyperforin however the exact mechanism of action is not known. Hyperforin is considered to be more active than hypericin (Shane-McWhorter 2007) however the total plant extract is more effective (Linde 2009).

Adverse effects and interactions with prescribed medication

Taken in isolation St John???s wort generally has some minor side effects including photosensitivity (skin sensitivity to light) in some people, cause gastric upset, sleeping disturbances and withdrawal-like symptoms if stopped suddenly (Shane-McWhorter 2007).

When taken with other prescribed medications St John???s wort preparations can alter the effectiveness of these drugs and should not be taken in combination (Barnes 2008). People taking St John???s wort should be advised to gradually taper the dose of St John???s wort rather than stopping suddenly.


Medications that can be affected by St John???s wort include oral contraceptives, warfarin, triptans (sumatriptan, naratriptan, rizatriptan and zolmitriptan) and Selective Serotonin Reuptake Inhibitors (citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline).

People who treat their diabetes with gliclazide (Xu 2008) or rosiglitazone (Hruska 2005) should take particular care if they are also using St John???s wort as it can reduce the effectiveness of these prescribed medications.

Use in women who are pregnant or breastfeeding

There is a lack of toxicity data for St John???s wort and therefore its use is not recommended in pregnancy or when breastfeeding (Barnes 2008).

Recommendations for people wanting to use St John???s Wort

Depression is serious and may need to be monitored. People with depression and diabetes should seek professional advice and discuss with their doctor any other medications that are currently being taken before considering using St John???s wort. The use of the herbal remedy for mild to moderate depression is justified but only when high quality extracts are used, on the advice of a healthcare professional (Linde 2009).


Barnes J, Anderson L and Phillipson JD (2008) Herbal Medicines on Medicines Complete [online]

Hruska MW, Cheong JA, Langaee YT et al (2005) Effect of St. John???s Wort administration on CYP2C8 mediated rosiglitazone metabolism. Clinical Pharmacology & Therapeutics; 77:

Linde K, Berner MM and Kriston L (2009) St John’s wort for major depression, Cochrane Database of Systematic Reviews, issue 4. Available from web

Shane-McWhorter, L (2007) Complementary & Alternative Medicine (CAM) supplement use in people with diabetes: a clinician???s guide. American Diabetes Association, Canada.

Xu H, Williams KM, Liauw WS et al (2008) Effects of St John???s wort and CYP2C9 genotype on the pharmacokinetics and pharmacodynamics of gliclazide. British Journal of Pharmacology; 153 (7): 1579-1586.

Further reading

Diabetes UK [online] Depression and diabetes.