If Manaus is the gateway to the Brazilian Amazon, the herbal shops at the municipal market are essential attractions. At the bustling Mercado Antonio Lisboa, marble floors are worn down by a century of footprints. The medicine shops deliver a variety of medicinal barks, leaves and roots. Among the herbal treasures displayed there are legendary sex-enhancers.

Even before visiting Manaus, I had learned that the use of catuaba and muirapuama together to increase libido and improve sexual function was very popular. Putting these plants together was exemplary of the ingenious way in which natives figure out how to combine plants to achieve specific health effects. Few reputed health-enhancing plants are as popular or as widely consumed among the natives of the northern Amazon river basin as the barks of two trees, catuaba Erthyroxylum catuaba and muirapuama Ptychopetalum olacoides. Both have been widely used by natives and non-natives for centuries, to increase libido and improve sexual potency, and the harvesting and sale of these two plants has become big business throughout Brazil.

Though modern science on catuaba and muirapuama is still modest, reports in scientific journals and at conferences have affirmed their sexual enhancing properties, and have broadened interest in their use. In catuaba, a group of alkaloids dubbed catuabine A, B and C are believed to enhance sexual function by stimulating the nervous system. In muirapuama, chemists have identified a group of sterols including beta-sitosterol, thought to be responsible for the herb’s aphrodisiac effects. In one study using muirapuama, 51 percent of men with erectile problems reported improvement, and 62 percent experienced an increase in libido.

Staying at a small hotel before heading up the Amazon River to work with shamans gave me an opportunity to inquire further into catuaba and muirapuama, and to check out the use of another popular Amazonian plant. I had seen dozens of guarana products at Antonio’s shop, and guarana sodas were everywhere. Throughout Manaus, dozens of guarana stands serve mixed fruit smoothies with herbs. Brazil may be a huge coffee producing nation, but guarana is the most adored caffeine-bearing plant of the country. Guarana is a dried paste made from the seeds of Paulinia cupana, a bushy tree which grows both wild and cultivated in the upper Amazon basin. Guarana seed paste contains 2.5 to 5 percent caffeine, and is used in soft drinks, syrups and guarana sticks. The sticks, which look like brown dynamite, are scraped on a grater, and the powder is put into beverages. At guarana stands, powdered guarana seed paste is added to blends of exotic fruits like acai, cupuacu, buriti, mango and papaya, resulting in sweet, energizing fruit smoothies.

In addition to the natural lift imparted by guarana–fortified shakes, many customers who frequent guarana stands also seek sexual stimulation. Every stand offers an herbal “super sex drink” which contains about a heaping teaspoon of powdered catuaba and muirapuama barks combined with another teaspoon of guarana. The people who work at the stands have countless anecdotes to share. My favorite was about the one hundred year old man who consumed a sex drink and then went home and chased his equally aged wife around the bedroom. Though surely apocryphal, the story spoke to the place that these herbs hold in popular Brazilian culture. At guarana stands, couples buy sex drinks together, and smile at each other suggestively as they drink. Men and women individually consume the herbal elixirs on the spot, and take more home in plastic bottles to their partners.

I asked a young man behind the counter of one guarana bar if the herbal sex drinks really worked. “Oh man,” he replied. “You better have a date. These drinks make the sexual feelings very strong, and you can just go and go all night long.” He took down jars of powdered guarana, catuaba and muirapuama from a shelf, and scooped a little of each onto a plate for me to taste.

A young woman making blender drinks behind the bar piped in. “We get so many people, especially couples, who come back here all the time for the sex drinks. They wouldn’t keep coming back if the drinks didn’t work for them.” The conversation spread to a couple of men and a woman waiting for blender drinks at the counter. One man told us “You know, with the catuaba, you get very potent.” The woman remarked that the barks in the sex drinks were very special gifts from the rainforest, and that we had to take care of the forest. A lot of trees were being cut down, and a lot of native people were getting pushed out of their ancestral homes. “The forest must be protected, and the native people must be helped. Be sure to tell that to the people back in the United States.”

If you want to experience the uplifting effects of catuaba, muirapuama and guarana for yourself, my pick of the week is Rainforest Nutrition. They have these herbs, and they know what they are doing. You can also find these remedies at natural food stores, including Whole Foods.