250 mg of 10% extract ×2 in the studies.
Barely affects weight; some change in body composition in men, not replicated.
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Forskolin is a diterpene extracted from the root of Coleus forskohlii, a plant in the mint family native to India and East Africa, whose pharmacological discovery in the 1970s opened an interesting avenue in cell biology: forskolin directly activates adenylate cyclase, the enzyme that produces cyclic AMP (cAMP), a universal second messenger that mediates the action of many hormones inside the body's cells.
This universal pharmacological action explains the theoretical appeal of forskolin as a supplement (activating lipolysis via cAMP, modulating thyroid function, improving cardiac contractility) but also its Achilles' heel: what is elegant in cell cultures translates poorly to humans by the oral route, where its bioavailability is low and its systemic effect is modest compared with the expectations the supplement industry has generated.
The most marketed indication for forskolin is fat loss, based on its ability to increase cAMP in adipocytes, which in theory should enhance lipolysis and energy expenditure; the available clinical trials are few and with modest results: one study in overweight men showed an increase in lean mass and a reduction in fat with 250 mg twice a day for 12 weeks, but another study in overweight women found no significant effect on body composition.
The clinical reality is that the effect on fat loss is small and heterogeneous, clearly lower than what the advertisements for commercial products suggest; anyone seeking to lose fat will get much better results with a moderate calorie deficit and strength training than with any forskolin supplement, however elegant the cellular theory may be.
The most solid clinical indication is topical use in glaucoma: eye drops with 1 percent forskolin reduce intraocular pressure comparably to ophthalmic beta-blockers such as timolol, with good local tolerability and without some of the systemic effects of beta-blockers; this indication is approved in some countries such as India and is used as an alternative or adjunct to conventional treatments.
In asthma, inhaled forskolin has been studied as a bronchodilator (activation of cAMP in bronchial smooth muscle is bronchodilatory) with modest results; in heart failure, intravenous forskolin improves cardiac function in selected cases but its oral use in this context has not shown clear benefit; in subclinical hypothyroidism, the data are anecdotal.
The doses studied range from 250 to 500 milligrams per day of extract standardized to 10-20 percent forskolin, divided into two doses with or without food; products with clear standardization and brand backing (ForsLean is the trademark with the most studies) are the most reasonable, whereas cheap generic products may have actual contents far below what is declared on the label.
Generally well tolerated orally; the most frequent adverse effects are digestive discomfort, occasionally hypotension (especially if combined with antihypertensives), and palpitations in sensitive people; people taking anticoagulants, antihypertensives, nitrates, or cardiac medication should be cautious because of additive interactions; it is contraindicated in active peptic ulcer (forskolin increases gastric secretion via cAMP) and should be avoided in pregnancy and breastfeeding because of limited data on reproductive safety.
Information, not medical advice. Scientific evidence reflects the quality of the studies.