The letters CF can stand for a few different things in the medical and nutrition world. Chronic fatigue and cystic fibrosis are two that spring to mind immediately. Let’s explore a third item that can be abbreviated CF: Coleus forskohlii. 

Coleus forskohlii is a perennial plant in the Lamiaceae family which also includes mint oregano marjoram basil rosemary and sage. The plant also goes by the name Plectranthus barbatus or Indian coleus and it grows primarily in the subtropical temperate climates of India Nepal Sri Lanka and Thailand. The root portion has a long tradition of use in Hindu and Ayurvedic medicine as well as folk medicine in Brazil China and tropical Africa. However the active constituent found in the roots forskolin wasn’t identified by Western scientists until 1974.

Forskolin is believed to be responsible for virtually all the pharmacological activities attributed to Coleus forskohlii. It is a lipid-soluble diterpene that penetrates cell membranes and activates the enzyme adenylyl cyclase (also called adenylate cyclase) which increases intracellular levels of cyclic AMP (cAMP). Activation of adenylate cyclase by forskolin is rapid and reversible which distinguishes forskolin from other compounds (e.g. hormones pathogens) that also activate this enzyme. cAMP is an important messenger compound for the proper biological response to hormones and other extracellular signals. It’s required for proper cellular communication in the hypothalamus and pituitary gland and for regulating feedback control of hormones. For this reason forskolin is sometimes included in supplements intended to support healthy thyroid function. 

Pharmacological activity associated with forskolin results primarily from this compound’s influence on cAMP. The many diverse effects of elevating cAMP may be why coleus forskohlii has been used for intestinal and liver conditions respiratory disorders heart disease nervous system disorders and more. There are few tissue systems not affected by cAMP. cAMP inhibits basophil and mast cell degranulation and histamine release lowers blood pressure and intraocular pressure inhibits platelet aggregation promotes vasodilation and bronchodilation stimulates lipolysis in adipose tissue and promotes thyroid hormone secretion. Conditions associated with reduced levels of cAMP include asthma cardiovascular disease psoriasis hypertension and obesity.

Regarding obesity adipocytes from obese women have lower adenylate cyclase activity than those of non-obese women. Promoting enzyme activity and stimulating cAMP production may be helpful in the seemingly unwinnable battle of the bulge. Animal and in vitro studies also support a potential role for coleus forskohlii in enhancing lipolysis and reducing body weight and fat accumulation.

Fortunately human studies also support a modest effect of forskolin for fat loss. And considering how mightily some people struggle to reduce their body fat modest effects are better than nothing! In a small but promising study of six overweight but otherwise healthy women twice daily supplementation with 250 mg of coleus forskohlii extract (standardized to 10% forskolin) for eight weeks resulted in significant decreases in body fat percentage without changes in diet or exercise habits. A separate study concluded that forskolin may not be a home run for fat loss but it could be helpful for preventing fat gain and it does so in the absence of any observed adverse effects on hematological profile. Studies in men are slightly more promising. A randomized double-blind placebo-controlled study showed that overweight and obese men who took 250 mg of 10% forskolin extract twice daily for twelve weeks experienced a decrease in body fat with increases in bone mass and free testosterone. Forskolin may also help boost thyroid function which could augment its fat loss effects for individuals whose stubborn fat loss is due to sluggish thyroid activity.

Aside from being marketed primarily as a “fat burner” these days forskolin also has anti-spasmodic effects and inhibits platelet aggregation. It may be especially helpful for asthma. In a small study comparing the effects of forskolin capsules and inhaled sodium cromoglycate for prevention of asthma attacks in patients with mild or moderate persistent asthma forskolin supplementation resulted in significantly fewer attacks than did the inhaler during the six-month study period. Among the forskolin group 40% (8/20 subjects) experienced an attack compared to 85% (17/20 subjects) in the sodium cromoglycate group. Another possible use for forskolin is in glaucoma and other conditions resulting from increased ocular pressure. Eyedrops containing forskolin have been shown to reduce ocular pressure with the length (but not magnitude) of the effect being dose-dependent. (The effects of a suspension containing 1% forskolin lasted 7 hours compared to 4 and 5 hours for 0.3% and 0.6% suspensions respectively.)