Coleus forskohlii is a perennial plant, with a strong, camphor-like odor. It is in the mint family. It grows well in warm temperate or subtropical areas. The plant is native to areas of India, Myanmar, Nepal, and Sri Lanka. Coleus has long been used in traditional Indian (Ayurvedic) medicine, but gained popularity when a chemical extract of the root called forskolin demonstrated properties that make it a potential treatment for asthma, bronchitis, glaucoma , congestive heart failure, and other conditions. Forskolin was first identified by Western researchers in the 1970s, but the effects of the whole coleus plant and its extracts have not been as well studied or understood.
Another species of coleus, Coleus kilimandschari, is found in parts of Africa and has been used in Rwandan folk medicine to treat infections and autoimmune diseases. Recent studies of Rwandan coleus indicate that it is effective against a variety of disorders involving destruction of red blood cells. As of 2002, however, Rwandan coleus has not been studied as intensively as Coleus forskohlii, and its extracts await further analysis.
Chinese research indicates that several diterpenoids found in the leaves and stems of coleus may be effective against leukemia cells. These recently discovered compounds, however, require further study and analysis.
Forskolin increases the levels of a cell-regulating compound called cyclic adenosine monophosphate (cAMP). This property allows it to stabilize mast cells, which contain histamine and other inflammatory substances. Preventing the release of these compounds could make forskolin valuable in the treatment of diseases with an allergic component, such as asthma and eczema .
Another benefit of the increase of cAMP is forskolin's ability to relax smooth muscles. The bronchioles, uterus, arteries, gastrointestinal tract, and bladder all contain smooth muscle that is responsive to the antispasmodic effects of forskolin. As an antispasmodic, it has potential applications for conditions that involve cramping or smooth muscle contraction. These include asthma, painful periods, angina, irritable bowel syndrome , bladder infections, and high blood pressure.
People suffering from asthma may benefit from the use of forskolin in its capacity as an antispasmodic. During an asthma attack, the smooth muscle within small passageways of the lungs (bronchioles) constricts and makes breathing difficult. The action of forskolin is similar to that of some standard inhalers containing such medications as albuterol, a beta agonist bronchodilator. Both substances relax the smooth muscle, and improve the person's breathing ability. Studies of forskolin for the treatment of asthma have shown positive results in both oral and inhaled preparations, although it is not commercially available in an inhaled formula at this time. Other allergic conditions, including eczema, may also respond well to forskolin. Levels of cAMP are reduced in the bronchioles and skin of people suffering from asthma and eczema. The lack of cAMP causes histamine release and subsequent allergic symptoms, including bronchoconstriction and local reaction. Forskolin may be able to prevent the onset of symptoms in susceptible people by increasing cAMP levels. It can theoretically be helpful for any condition that is caused, wholly or partially, by an allergic reaction. Professional help should be sought to use forskolin for this indication, particularly because of potential interactions with other medications used for asthma.
Psoriasis can be treated by taking forskolin supplements. In this condition, skin cells multiply at a rate much greater than normal. Itchy, silvery patches are formed on the skin. This may be due to an imbalance of cell regulating chemicals, including cAMP, that can be normalized by forskolin.
Cardiovascular diseases, such as congestive heart failure, angina, and high blood pressure, have the potential to be treated by forskolin. The extract appears to increase the contractility of the heart, and relax the smooth muscles in the walls of the arteries. The relaxation of the arteries decreases blood pressure, pain due to angina, and strain on the heart. Maximum benefit may be achieved in conjunction with other botanicals or medications, such as dobutamine.
Blood vessels in the brain are dilated by forskolin, which could have clinical applications for patients who are at risk of, or recovering from, stroke . Forskolin also decreases the risk of abnormal clotting. This is another desirable effect for stroke patients and those with other cardiovascular conditions that cause, or result from, increased susceptibility to blood clots .
The high pressure inside the eye that occurs with glaucoma has been reduced in research studies with the use of forskolin drops. Eye drops made with forskolin are not yet available to the consumer, but oral preparations have the potential for beneficial effects.
An infusion of the leaves of Coleus forskohlii has traditionally been used in Indian medicine for the treatment of gas and bloating. This effect has not been subjected to study.
Other potential applications for forskolin, which are not yet adequately studied, include treatment for weight loss, hypothyroidism , malabsorptive conditions, depression, cancer metastasis, and immune dysfunction.
Crude preparations of Coleus forskohlii may not contain enough forskolin to exert a clinical effect. Forskolin extracts are available. One recommended dose is 50 mg two or three times daily of a preparation containing 18% forskolin. A health care provider knowledgeable in the clinical use of botanicals should be consulted before undertaking treatment with this extract.
Forskolin can be a powerful medication, and has effects on many systems of the body. It has been described as a central nervous system depressant. It should not be taken for an indication without a person being aware of potential effects on other parts of the body. For this reason, professional supervision is recommended.
People with low blood pressure or gastric ulcers may wish to avoid forskolin due to potential exacerbation of these conditions. Children, or women who are pregnant or breastfeeding, should also avoid this substance due to the current lack of data about potential risks. Similarly, those who have chronic liver or kidney disease should use great caution in taking this medication, particularly if other herbs or medications are being used.
Forskolin does not appear to be toxic based on studies done on animals; however, it has been reported by veterinarians to lower the blood pressure of cats and dogs. As of 2002, the most common side effect reported for coleus leaves is contact dermatitis (skin rash) in people who are allergic to the plant. The overall safety and side effects of forskolin, however, have not yet received an in-depth analysis.
Forskolin may intensify the effects of other medications taken concurrently. Caution should be used when taking any botanical or prescription medication. Forskolin should not be taken in conjunction with anti-asthmatic, anticoagulant or antihypertensive medications without the supervision of a health care provider.
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National Institute of Ayurvedic Medicine. 584 Milltown Road, Brewster, NY 10509. (845) 278-8700. <www.niam.com>.