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Coleus
Common name: Makandi
Botanical name: Coleus forskohlii
© Martin Wall
Parts used and where grown
This attractive, perennial member of the mint (Lamiaceae) family originated in the lower elevations of India. It is now grown around the world as an ornamental plant. The root is used medicinally.
Coleus has been used in connection with the following conditions (refer to the individual health concern for complete information):
| Science Ratings | Health Concerns |
|---|---|
 |
Asthma (forskolin) Glaucoma (forskolin) |
 |
Cardiomyopathy (forskolin) Congestive heart failure Hypertension (forskolin) Obesity Psoriasis |
 Reliable
and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies
suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal
or no scientific evidence. For a supplement, little scientific support and/or minimal health
benefit. |
|
Historical or traditional use (may or may not be supported by scientific studies)
As recorded in ancient Sanskrit texts, coleus was used in Ayurvedic medicine1 to treat heart and lung diseases, intestinal spasms, insomnia, and convulsions.
Active constituents
Forskolin, a chemical found in coleus, activates the enzyme adenylate cyclase.2 This enzyme is a turnkey compound that initiates a cascade of critical events within every cell of the body. Adenylate cyclase and the chemicals it activates comprise a “second messenger” system that is responsible for carrying out the complex and powerful effects of hormones in the body. Stimulation of the second messenger system by forskolin leads to blood vessel dilation,3 inhibition of allergic reactions,4 and an increase in thyroid hormone secretion.5 Forskolin has other properties as well, including inhibition of the pro-inflammatory substance known as platelet-activating factor (PAF)6 and inhibition of the spread of cancer cells.7
Studies in healthy humans, including at least one double-blind trial, have shown that direct application of an ophthalmic preparation of forskolin to the eyes lowers eye pressure,8 9 thus reducing the risk of glaucoma. Direct application of the whole herb to the eyes has not been studied and is not recommended.
Forskolin may help dilate blood vessels and improve the forcefulness with which the heart pumps blood. A preliminary trial found that forskolin reduced blood pressure and improved heart function in people with cardiomyopathy.10 It is unknown if oral coleus extracts would have the same effect. A small double-blind trial found that inhaled forskolin could decrease lung spasms in asthmatics.11 It is unclear if oral ingestion of coleus extracts will provide similar benefits.
How much is usually taken?
Coleus extracts standardized to 10 to 18% forskolin are available. While some doctors expert in herbal medicine recommend 50–100 mg two to three times per day of standardized coleus extract, these amounts are extrapolations and have yet to be confirmed by direct clinical research.12 Most studies have used injected forskolin, so it is unclear if oral ingestion of coleus extracts will provide similar benefits in the amounts recommended above. Until ophthalmic preparations of coleus or forskolin are available, people with glaucoma should consult with a skilled healthcare practitioner to obtain a sterile fluid extract for use in the eyes.
Are there any side effects or interactions?
Few adverse effects of coleus have been reported. It should be avoided in people with ulcers, because it may increase stomach acid levels. Direct application to the eyes may cause transitory tearing, burning, and itching. The safety of coleus in pregnancy and breast-feeding is unknown.
Are there any drug
interactions?
Certain medicines may interact with coleus. Refer to drug interactions for a list of those medicines.
References
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.