Yohimbine is a drug derived from the bark of two types of trees found in Africa, the Pausinystalia yohimbe and Corynanthe
yohimbe. I call yohimbine a drug because it can alter the normal physiology of the body, which puts it in a different
category than most supplements. It's long been considered an aphrodisiac and erection aid by practitioners of traditional
medicine. In fact, before Viagra, yohimbine, the active ingredient of yohimbe bark, was the treatment of choice for
millions of impotent men around the world.
Yohimbine was first marketed to bodybuilders for its supposed ability to increase testosterone. After extensive animal
and human testing, however, scientists found it had no action on androgen production. The claim of increased testosterone
most likely came from those who heard it improved libido, which mistakenly led them to believe its mechanism of action was
via increased androgen production. Though their intentions were good, their science was very wrong.
Laboratory tests on yohimbine reveal it has potent effects on the nervous system and other non-neural tissues, such as
the heart, lungs, mucous membranes, eyes, penis and adipose. As far as its aphrodisiac properties, alterations in sex drive
are minimal while taking yohimbine; the main effect of the drug is on the penis itself. Yohimbine acts as a potent
vasodilator, increasing the blood supply to the penis. The actions on this tissue are complex, but you can think of it as
improved plumbing: opening the blood flow into the penis, and decreasing the flow leaving the penis.
Yohimbine blocks alpha-receptors, thus increasing stimulation of the parasympathetic nervous system (one function of which
is to open specific blood vessels). It also decreases the activity of the sympathetic system (one function of which is to
close certain blood vessels). In many instances, these systems oppose each other, thus keeping certain body functions in
Of interest to bodybuilders are yohimbine's effects on fat metabolism. Since yohimbine blocks the alpha receptors, an increase
in lipolysis may result due to increased levels of norepinephrine in the bloodstream. Norepinephrine has a marked effect on
fat utilization by the body because it directly stimulates a substance called hormone- sensitive lipase. By turning on this
enzyme, a rapid break-down of triglycerides and fatty acids occurs. Increased release of free fatty acids into the blood means
that you're burning stored fat - big time.
Though yohimbine, in theory, could be a potent lipolytic agent, we need to look at the human research on the topic to confirm
this hypothesis. To date, there are only a few studies looking at yohimbine and fat loss that, unfortunately, provide only a
piece of this complex puzzle. Fat loss is a product of several components, including genetic predisposition, various hormonal
factors, activity level and dietary habits. To posit that simply blocking certain receptors will make you lean is to
oversimplify an intricate chain of events. The research on yohimbine and fat loss reflects this dilemma.
One study done in France and published in the Journal of Pharmacology showed no effect on lipolysis or free fatty acid release
in subjects receiving 18 milligrams of yohimbine per day. But two recently conducted investigations demonstrated that yohimbine
supplementation does increase free fatty acid release and weight loss in obese subjects. While these studies look interesting,
more work is needed to establish dosages necessary for fat loss.
Should bodybuilders take this drug to get lean? While yohimbine does show some efficacy as a fat-loss agent, long- term use/abuse
may cause some nasty side effects, including chronic fatigue, muscle weakness, stomach discomfort, mild tremors, nausea, mental
disturbance and skin flushing. In addition, if you're on an antidepressant medication, yohimbine is a no-no.
A potential problem for supplement buyers is that some brands of yohimbine purchased over the counter are far from pure. Quality,
as well as potency, cannot be guaranteed because yohimbine is classified as a food supplement and, hence, unregulated. You can't
be sure about the dosages you're consuming, which could be an issue for some individuals with underlying or hidden medical
conditions, or hypersensitivity to alpha receptor blockade. Take too much and a serious medical emergency could ensue. You're
much better off with brands from well-established companies. Staying under a doctor's care while using yohimbine would be your