Forskolin extract from coleus forskohlii, benefit, side effects, review of medical uses and dosage

The diterpene forskolin directly activates adenylyl cyclase and raises cyclic AMP levels in a wide variety of cell types.

Where it is found
Forskolin is found in the Coleus plant (Coleus forskohlii), used by Ayurvedic doctors.

Mechanism of action
Forskolin is used to raise levels of cyclic AMP (cAMP) in the study and research of cell physiology. Forskolin activates the enzyme adenylyl cyclase and increasing the intracellular levels of cyclic Adenosine Monophosphate (cyclic AMP or cAMP). Cyclic AMP is an important signal carrier necessary for the proper biological response of cells to hormones and other extracellular signals. It is required for cell communication in the hypothalamus/pituitary gland axis and for the feedback control of hormones. It acts by activating protein kinase A.

Supplements over the counter
There are many companies that sell this herbal extract, either by itself, or as part of a coleus extract.

Forskolin 10 mg, from 98 % extract
Coleus Forskohlii Root Extract standardized to contain 18% forskolin (9 mg) 50 mg
Coleus forskohli (root) extract 100mg, providing 10 mg of forskolin
Coleus forskohlii Root 210 mg
Coleus Forskolli root extract 20:1 (Equivalent to 5,000 mg) 250 mg
Forskohlii Root Extract (Forslean) (20% forskohlin) 125 mg and Forskohlii Root 100 mg
Forskohlii (Coleus forskohlii) Root Extract (standardized for 1% forskohlin) 250 mg

Composition
This plant contains forskolin along with forskoditerpenoside C, D, and E and forskoditerpene A. Additional substances include 14-deoxycoleon U, demethylcryptojaponol, alpha-amyrin, betulic acid, alpha-cedrol and beta-sitosterol.

Studies on the chemical constituents of Coleus forskohlii
Zhong Yao Cai. 2009 Sep; School of Pharmacy, Fudan University, Shanghai 200032, China.
To study the chemical constituents in the aerial parts of Coleus forskohlii. The compounds were isolated by various column chromatographic methods, and their structures were identified by spectroscopic methods. Twelve compounds were isolated and identified as chamaecydin, 6 alpha-hydroxydemethylcryptojaponol, alpha-cedrene, oleanolic acid, forskolin G, forskolin J, 1,6-diacetyl-9-deoxyforskolin, forskolin A, forskolin H, 6-acetyl-1-deoxyforskolin, betulinic acid, beta-sitosterol. Compounds 1 - 3 are isolated from Coleus genus for the first time, and compound 4 is isolated from C. forskohlii for the first time.

Human studies
Clinical trials thus far indicate this substance may be useful for asthma and erectile function.

Asthma
Forskolin versus sodium cromoglycate for prevention of asthma attacks: a single-blinded clinical trial.
J Int Med Res. 2006 Mar-Apr; González-Sánchez R, Trujillo X, Trujillo-Hernández B, Vásquez C, Huerta M, Elizalde A. Servicio de Pediatría, Hospital del Instituto Mexicano del Seguro Social, Manzanillo, Colima, México.
To determine the efficacy of forskolin in preventing asthma attacks, we performed a single-blinded clinical study in children and adult out-patients at a public hospital in Mexico. Forty patients of either sex with mild persistent or moderate persistent asthma were assigned randomly to 6 months of treatment with forskolin at 10 mg/day orally (capsules) or with two inhalations of sodium cromoglycate every 8 h, i.e. three times a day. The number of patients who had asthma attacks during the treatment period was significantly lower among those receiving forskolin (8/20, 40%) than among those receiving sodium cromoglycate (17/20, 85%). Values of forced expiratory volume in 1 s and forced expiratory flow, mid-phase, A similar in the two groups during the treatment period. We conclude that forskolin is more effective than sod cromoglycate in preventing asthma attacks in patients with mild persistent or moderate persistent asthma.

Protective effect of forskolin in acetylcholine provocation in healthy probands. Comparison of 2 doses with fenoterol and placebo
Wien Med Wochenschr. 1986 Dec 31; Kaik G, Witte PU.
Forskolin, a potent adenylate cyclase activating diterpene-derivative, isolated from the Indian plant Coleus forskohlii, was tested double-blind and cross-over in 12 healthy volunteers (nonsmokers) by whole body plethysmography. All drugs were administered by metered dose inhalers. The bronchodilating effect (after 5 minutes) was as good as following fenoterol. At the beginning (after 3 and 5 minutes) the protective effect against inhaled acetylcholine was as good as following fenoterol while later on (after 15 and 30 minutes) fenoterol resulted in a stronger action.

Erectile function, impotence
Intracavernosal forskolin: role in management of vasculogenic impotence resistant to standard 3-agent pharmacotherapy.
J Urol. 1997 Nov; Mulhall JP, Daller M, Traish AM, Gupta S, Park K, Salimpour P, Payton TR, Krane RJ, Goldstein I. Department of Urology, Boston University School of Medicine, Massachusetts, USA.
We investigated forskolin, a direct adenylate cyclase activator, as an intracavernosal vasoactive agent in management of vasculogenic impotence. Concentration responses for forskolin and prostaglandin E1 induced relaxation of phenylephrine precontracted strips of human corpus cavernosum smooth muscle were constructed in vitro. Cyclic adenosine monophosphate (cAMP) synthesis was determined with papaverine, phentolamine, prostaglandin E1 and forskolin in human corpus cavernosum smooth muscle cell cultures. Dose-dependent hemodynamic responses to intracavernosal forskolin (5 to 20 micrograms) were evaluated in a New Zealand White rabbit model. Safety and efficacy outcome data were obtained in vasculogenically impotent patients who signed informed consent and met strict inclusion and exclusion criteria that included having had standard self-injection therapies fail. In vitro forskolin and prostaglandin E1 alone caused concentration dependent relaxation with an EC50 of approximately 200 nm. and 16 nm., respectively. When the 2 agents were combined, the concentration response curve for relaxation shifted to the left. cAMP production was highest in cells treated with prostaglandin E1 and forskolin and was unaffected by papaverine or phentolamine. In 3 animals, equilibrium intracavernosal pressure and duration of erection had a dose dependent increase. Clinical investigation in 31 patients showed no adverse events 18 months of followup. Overall 61% reported improvement in rigidity and/or erection duration using intracavernosal forskolin, papaverine, phentolamine and prostaglandin E1. Forskolin is a United States Food and Drug Administration nonapproved vasoactive agent that acts in synergism with prostaglandin E1 to induce smooth muscle relaxation. In combination with other vasoactive agents, forskolin has demonstrated preliminary safety and efficacy in patients with vasculogenic impotence resistant to standard 3-agent pharmacotherapy.

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Obesity
The results using forskolin supplements to help lose weight have been mixed, with one study showing weight loss benefits while another did not indicate any benefit.

Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men.
Obes Res. 2005 Aug; Godard MP, Johnson BA, Richmond SR. University of Kansas, Department of Health, Sport and Exercise Sciences, Applied Physiology Laboratory, Lawrence, KS 66045, USA.
This study examined the effect of forskolin on body composition, testosterone, metabolic rate, and blood pressure in overweight and obese (BMI > or = 26 kg/m(2)) men. Thirty subjects were studied in a randomized, double-blind, placebo-controlled study for 12 weeks. Forskolin was shown to elicit favorable changes in body composition by significantly decreasing body fat percentage (BF%) and fat mass. Additionally, forskolin administration resulted in a change in bone mass for the 12-week trial compared with the placebo group. There was a trend toward a significant increase for lean body mass in the forskolin group compared with the placebo group. Serum free testosterone levels were significantly increased in the forskolin group  compared with the placebo group. The actual change in serum total testosterone concentration was not significantly different among groups, but it increased 16% in the forskolin group compared with a decrease in the placebo group. Oral ingestion of forskolin (250 mg of 10% forskolin extract twice a day) for a 12-week period was shown to favorably alter body composition while concurrently increasing bone mass and serum free testosterone levels in overweight and obese men. The results indicate that forskolin is a possible therapeutic agent for the management and treatment of obesity.

Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women.
J Int Soc Sports Nutr. 2005 Dec 9; Henderson S, Magu B, Rasmussen C, Lancaster S, Kerksick C, Smith P, Melton C, Cowan P, Greenwood M, Earnest C, Almada A, Milnor P, Magrans T, Bowden R, Ounpraseuth S, Thomas A, Kreider RB. Exercise & Sport Nutrition Laboratory, Baylor University, Waco, TX.
This study investigated the effects of Coleus Forskohlii on body composition, and determined the safety and efficacy of supplementation. In a double blind and randomized manner, 23 females supplemented their diet with ForsLean trade mark (250 mg of 10% Coleus Forskohlii extract, or a placebo two times per day for 12-wks. No significant differences were observed in caloric or macronutrient intake. Coleus Forskohlii tended to mitigate gains in body mass with no significant differences in fat mass, fat free mass, or body fat. Subjects in the Coleus Forskohlii group tended to report less fatigue, hunger, and fullness. No clinically significant interactions were seen in metabolic markers, blood lipids, muscle and liver enzymes, electrolytes, red cells, white cells, hormones (insulin, TSH, T3, and T4), heart rate, blood pressure, or weekly reports of side effects. Results suggest that Coleus Forskohlii does not appear to promote weight loss but may help mitigate weight gain in overweight females with apparently no clinically significant side effects.

Interaction with dietary supplements

Weight loss products
I just received my order for Diet Rx and forskolin supplements. My question: is it OK to combine the two? Example: taking 1 Diet Rx and 1 forskolin pill daily?
    We suggest taking each one separately for a week before combining. This way you can tell how each one is working by itself.