If you have read anything about wild yam, you have probably run into the word diosgenin within a paragraph or two. It gets mentioned the way people mention an ingredient they assume you already understand, and then the sentence moves on. Almost nobody stops to tell you what it is, where it was found, or why a root from the forests of southern Mexico ended up at the center of one of the stranger industries of the twentieth century.
If you heard wild yam come up on The Joe Rogan Experience, where a guest described pharmacy hormones being made from Mexican wild yam, this is the story behind it. It is worth your time. It has a stubborn chemist, a company started in a Mexico City lab, and tens of thousands of rural harvesters whose names never made it into the textbooks.
What Diosgenin Is
Diosgenin is a plant steroid — technically a steroidal sapogenin — found in the roots of several species of Dioscorea, the true yams, and in smaller amounts in plants such as fenugreek. In the living plant it is mostly bound to sugars as a larger molecule called a saponin; chemists free it by breaking those sugars off.
Its shape is what made it valuable. Diosgenin has the four-ring skeleton shared by every steroid, which meant that in the right hands it could serve as a starting point for building other steroid molecules. That is a property of the molecule on a lab bench, and it tells you nothing about what the root does on its own.
A Chemist Who Would Not Take No
In the late 1930s, steroid hormones were among the most expensive substances in medicine. They were extracted in tiny quantities from animal sources, and there was not nearly enough to go around.
Russell Marker, a chemist working at Penn State, developed a short sequence of reactions for turning plant sapogenins into progesterone. It is still known as the Marker degradation, and the American Chemical Society later designated his work a National Historic Chemical Landmark. That conversion is laboratory chemistry — deliberate, multi-step processing with industrial reagents — and the human body does not carry it out.
What Marker lacked was a plant rich enough to make the process pay. He went looking in Mexico and, in the state of Veracruz, found a large yam the locals called cabeza de negro, Dioscorea mexicana. Neither the drug companies he approached nor his own university would back a Mexican venture. So he went anyway.
Syntex and the Mexican Steroid Industry
In 1944 Marker co-founded a company in Mexico City called Syntex. He left within about a year after a falling-out with his partners, but the company outlasted the quarrel by decades. Under chemists including George Rosenkranz and a young Carl Djerassi, Syntex turned diosgenin into a range of steroid compounds, and Mexico became, for a time, the world's leading supplier of the raw material for them.
In 1951 a Syntex team that included Djerassi and a Mexican chemistry student named Luis Miramontes synthesized norethindrone, one of the compounds behind the first oral contraceptives. It is one of the few moments in modern pharmaceutical history where a Mexican lab, working from a Mexican plant, sat at the very front of the field.
Barbasco: The People Who Dug the Roots
Here is the part most tellings leave out. Cabeza de negro was soon replaced by a better-yielding relative, Dioscorea composita, known in Mexico as barbasco. It grew wild in the tropical forests of southern Mexico, especially in Veracruz and Oaxaca, and nobody farmed it at scale. Every root that reached a processing plant was dug by hand.
The people who dug it were campesinos — small farmers and their families, many of them Indigenous, who took up barbasco harvesting as a way to earn cash between crops. The historian Gabriela Soto Laveaga documents this in Jungle Laboratories, and her central point is hard to shake: an industry celebrated as a triumph of chemistry depended on rural labor and local knowledge of the forest that the chemists themselves did not have. The pickers knew where the plant grew and how to find it. Without them there was no raw material at all.
By the 1970s the Mexican government had stepped in with a state company, Proquivemex, to give harvesters a larger share of the trade. It arrived late. Drug makers were already moving to other starting materials and other countries, and the barbasco economy wound down over the following years.
Where That Leaves the Wild Yam in Your Cream
You may be wondering how much of this connects to a jar on your bathroom shelf. Less than the word “yam” suggests.
The industrial story belongs to the Mexican species, D. mexicana and D. composita. The wild yam in our cream is Dioscorea villosa, the North American woodland vine with the long folk record covered in The Ancient Roots of Wild Yam. They are related plants, and they have had very different careers.
So you can set the chemistry to one side. What you are choosing when you choose a wild yam topical is a plant with a long record of traditional use, in a cream you enjoy putting on your skin. That is a real reason, and a perfectly good one, even though it is a smaller one than the lab story implies. Whether it is for you is your call to make.
When a Label Is Not Enough
If you are managing a health condition, taking prescription medication, pregnant or trying to be, or dealing with symptoms that are disrupting your life, talk to a qualified healthcare provider before adding any botanical. You deserve an answer about your own body, not a history lesson.
Common Questions
What is diosgenin?
Diosgenin is a plant steroid, a steroidal sapogenin, found in the roots of several Dioscorea yams and in smaller amounts in plants such as fenugreek. From the 1940s it was used as an industrial starting material for making steroid compounds in a laboratory.
What is barbasco?
Barbasco is the Mexican name for Dioscorea composita, a wild yam from the tropical forests of southern Mexico. Its roots were hand-harvested by rural workers as the raw material for Mexico's mid-century steroid industry.
Who was Russell Marker?
An American chemist who developed the Marker degradation, a laboratory process for converting plant sapogenins such as diosgenin into progesterone, and who co-founded the Mexico City company Syntex in 1944.
Is Mexican wild yam the same as the wild yam in skincare?
Not necessarily. The steroid industry relied on Mexican species, D. mexicana and D. composita. Ours uses Dioscorea villosa, a related North American species, and the species name on any label is the thing to check.
Is diosgenin still used by drug makers today?
It is still one source among several, but it lost its central role decades ago as manufacturers moved to other plant materials and other supply countries.
The pickers never saw the inside of a laboratory, and most of the people who benefited from their work never heard the word barbasco. It is still a good thing to know, the next time you see a yam on a label.