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Health Effects of Coleus Forskohlii

The Ayurvedic botanical offers many health benefits including cardiovascular wellness and enhanced lean muscle mass.

Coleus (Coleus forskohlii) is an herb used in Ayurvedic medicine for promoting healthy cardiovascular, eye, respiratory and digestive function.¹ Its active principle is a diterpene known as forskolin.² Forskolin stimulates and activates the enzyme adenylate cyclase in the heart and smooth muscle. This causes increased production of cyclic AMP (cAMP), which causes calcium channels to open and intracellular calcium concentrations to increase, resulting in increased contractility of heart muscle and relaxation of smooth muscle.^3,4,5,6 cAMP is one of the most important regulators of endocrine health, brain chemistry and oxidative metabolism. Researchers speculate forskolin might also activate adenylate cyclase in other cells of the body, such as platelet cells and cells in the thyroid, pancreas, adrenal or pituitary glands.⁷

While coleus offers many health effects, it is currently best known for its impact on weight management. Forskolin has been shown to promote lipolysis (the breakdown of fat in the fat cells) and weight loss. In one study, six significantly overweight women were given 250 mg Coleus (standardized for 10-percent forskolin), twice daily for eight weeks, while maintaining previous exercise and diet habits.⁸ Intervention yielded an average weight loss of 9.17 pounds, almost an 8-percent reduction in percentage body fat, and a 4.23-percent increase in percentage of lean muscle—with no side effects. In a longer (12-week) study in mildly overweight women (n=19), providing 250 mg Coleus twice daily had no effect on weight loss; however, subjects taking Coleus experienced less hunger and less fatigue, and were more successful and preventing weight gain.⁹

The effects are certainly not gender dependent. In a double blind, randomized study, 30 overweight and significantly overweight men were given 250 mg Coleus (10 percent forskolin) twice daily, or a placebo, for 12 weeks.¹⁰ The men taking Coleus had a significant decrease in body fat percentage (11.23 percent) and 6-percent increase in lean mass, compared to a 1.73 percent decrease in body fat and less than 3-percent lean mass increase in placebo group. Further, there was a 17-percent increase in total testosterone and a 3.47-percent increase in free testosterone in the Coleus group, with a decrease in both measures in the placebo group. Again, there were no side effects.

In considering the three studies, it appears 250 mg Coleus (standardized for 10 percent forskolin) given twice daily is effective in the treatment of overweight and significantly overweight individuals, but not mildly overweight individuals. The data seems to indicate, therefore, Coleus is indicated for substantial weight loss, not just for five or ten pounds.

Cardiovascular Health

Both animal and clinical studies demonstrate forskolin significantly promotes healthy blood pressure levels within a normal range.^11,12 A clinical trial in patients with suboptimal heart function found intravenous forskolin significantly promoted diastolic blood pressure within a healthy range without increasing myocardial oxygen consumption; left ventricular function also improved.¹³ In a similar study, intravenous forskolin given to patients with suboptimal heart function resulted in healthy vascular resistance and left ventricle contractility.¹⁴ Subjects also exhibited a healthy level of arterial pressure accompanied by symptomatic flush. Forskolin’s ability to reduce platelet aggregation is of additional benefit in cardiovascular health.^15,16 In animal research, forskolin has also demonstrated a direct effect on cerebrovascular vasodilation via cAMP activation.¹⁷

It is important to note consumers taking anticoagulant or antihypertensive medications should use Coleus with caution, as forskolin could potentiate the effects of those drugs.^18,19

Additional Health Benefits

In vitro research indicates forskolin has potent immune stimulating properties.^20,21 In addition, forksolin seems to support anti-mutagenic functions in the body. Proliferation of mutated cells induces platelet aggregation, which stimulates the platelets to release substances that further promote the growth of mutated cells.²² In animal research, forskolin reduced the proliferation of mutated lung cells by 70 percent.²³ This may be a result of forskolin’s ability to reduce platelet aggregation.^24,25

Further, forskolin appears to stimulate thyroid hormone release and increase the production of thyroid hormone production.^26,27 In addition, forskolin has been shown to stimulate digestive secretions, including hydrochloric acid, pepsin, amylase and pancreatic enzymes, suggesting a potential benefit for digestive disorders.²⁸