Cable TV here is currently being flooded for commercials for a product called Zestra. The claims are intriguing - women who apply this oil to their genitals have an increase in sensation and sexual arousal, and this leads to better sex. The product supposedly works on normal women, as well as those experiencing decreased arousal. The Zestra ads and websites cite published scientific research to back up their claims. But do these claims stand up to scrutiny? Does Zestra really work? Aphrodisiology looks into it...

Zestra claims it "increases female sexual sensation,arousal and pleasure." It does so by increasing genital sensory nerve conduction velocity as well as genital blood flow, when topically applied".

As a scientific herbalist, I started by finding out what is in Zestra, and looking for possible effects the product might have.

Zestra contains the following ingredients:

• Borage Oil
• Evening Primrose Oil
• Angelica Extract
• Coleus Extract
• Vitamin C
• Vitamin E

Borage oil and Evening Primrose oil are both loaded with omega-3 fats like gamma-linoleic acid. There is increasing evidence that the modern diet is impoverished when it comes to these beneficial oils. Ray Sahelian has written about the general and sexual invigorating properties of omega-3 fish oils, and there is every reason to believe that that that borage and Primrose oil have a similiar effect.

The old adage that fish is brainfood has been confirmed by recent studies, which show that nerve function can improve when fish oils are added to the diet. And it isn't a stretch to suggest that a local application of these beneficial compounds might have a desirable local effect on nerves in the genital region, although this has been proven.

Angelica has long been a prominent female remedy among herbalists. Chinese Angelica, or Dong Quai, in particular, appears in many formulas for PMS and menopause difficulties. Angelica is rich in a compound called ostheole, which has estrogen-like properties.

Osthole has demonstrated an estrogen-like effect in two tests on osteoporosis, and in one test on spatial navigation in ovariectomized lab animals. (PMID:12081139, PMID: 9275709, PMID:15154281)

Coleus Extract is an ambiguous ingredient - there are so many different types of coleus plant. One particular type of coleus extract (from Coleus forshkolii) does have some remarkable chemicals, including forskolin. Over 17,000 scientific studies have been conducted that use forskolin in some way. Forskolin stimulates a particular set of energy pathways in the cells that involve ATP and AMP; caffeine is another herbal extract that affects ATP and AMP, although in a different way than forskolin.

About ten years ago, many thought that forskolin would be a new wonder drug for treating conditions as different as psoriasis and some types of heart diseases. Forskolin hasn't advanced as a therapeutic medicine for any condition, but remains a work-horse in biochemical studies, as it has some specific and unusual effects on energy in cells. Will coleus extract be the new female Viagra? Impossible to say with such limited evidence, but I will confidently predict that some therapeutic use will be found for forskolin, someday.

User Experiences with Zestra seem to be hit or miss - a review of 90 customer evaluations I saw on on drugstore.com indicated 50% were very satisfied and think it is the greatest thing since sliced bread, while about 30% said it didn't do anything at all. I'm not sure how accurate that information is, given the non-scientific way that the data was collected.

The most common complaints were over the smell. Some people really didn't like the smell, which they compared to bubble gum - other women (maybe the younger ones?) thought the smell was great.

A few women reported that it caused some irritation or burning sensations, which is not surprising for any oil applied to sensitive genital tissues.

One woman said that there were no effects with the first use, but that the second use saw a big response - perhaps the body chemistry had to be primed.

Aphrodisiology's Verdict is still out on Zestra. There is a theory on how it works, although the research is still weak. And the testimonials are mixed, and are not the same as a controlled study. The ingredients are fairly safe and don't seem to pose a big risk. The cost isn't negligble, but can be thought of as a movie with snacks, and it averages out to $3 per night of passion ... not bad, if it helps you.