NEPAL

The prized tonic starts as a fungus that infects a caterpillar, hollows it out, and sprouts from its corpse.
Gram for gram it can cost more than gold, and the evidence for what it does is oddly thin.

Cordyceps  ·  Ophiocordyceps sinensis (yarsagumba)  ·  Mechanism: cordycepin (aerobic)

High on the Himalayan plateau grows one of the strangest and most valuable substances in all of traditional medicine. Cordyceps is a parasitic fungus that infects the larva of a moth underground, slowly kills it, mummifies it, and in spring sends a thin dark stalk up out of the dead caterpillar's head.

In Nepal and Tibet it is yarsagumba, loosely, winter worm and summer grass, and it has been gathered by hand for centuries and prized for stamina, breath, and vigor. Today it is so sought after, and so scarce, that the best wild specimens can sell for more than their weight in gold, a vital cash crop for whole mountain communities.

That astonishing value rests on a long reputation as a tonic for energy and endurance, the thing a worn body reaches for when it is exhausted and short of breath. It is the ultimate exotic vitality remedy, which is exactly why it deserves a good hard look.

There is a catch few buyers ever notice, hiding in plain sight in the supplement aisle. The cordyceps in almost every capsule is not the fabled wild fungus at all.

Because the wild caterpillar fungus is so rare and so costly, nearly all of the research, and nearly every supplement, uses a cultivated substitute grown in a lab, a fermented strain or a related species raised on grain. Those cultivated forms still carry the active compounds, chiefly one called cordycepin, which is thought to act on how cells produce and use their energy.

The human evidence for all that is real but modest and quite mixed. A handful of small trials suggest cultivated cordyceps can nudge up aerobic capacity and stamina, mostly in older or less-fit people, while trials in trained athletes tend to find nothing at all, so it may help the unfit breathe a little easier but is no engine for the already-fit.

The capsule is lab-grown. The gold-priced wild fungus is mostly a story.

So the honest verdict is a genuinely intriguing fungus with a small, uneven benefit for endurance, wildly oversold as an energy cure-all. If you do try it, the cultivated extract is the sensible and affordable choice, not the eye-watering wild kind, and treat it as a low-risk maybe rather than a real tonic, especially if you take immune-affecting medication, where its effects on the immune system are a good reason to ask your doctor first.

The how-to

If you are curious, buy the affordable cultivated extract, expect a small edge at most, and skip the wild fortune.

Skip the astronomically priced wild yarsagumba, which is endangered and largely absent from real supplements anyway, and choose a cultivated cordyceps extract, either a CS-4 fermentation or a Cordyceps militaris product standardized for cordycepin, from a reputable, tested brand. Quality and mislabeling are common problems here, so the source matters a great deal.
Trials generally used a gram or a few grams a day of cultivated extract over several weeks, so give it real time and judge it honestly by your stamina, not by how you feel on the first day. It is not fast-acting.
At most, expect a small lift in aerobic capacity and endurance, most noticeable if you are older or unfit and only just getting active, and probably nothing if you are already well-trained. It will not transform your energy.
Cultivated cordyceps is generally well tolerated, with occasional mild stomach upset. Because it can stimulate the immune system, ask your doctor first if you have an autoimmune condition or take immune-suppressing medication, be cautious alongside blood thinners or diabetes drugs, and stick to tested products, since wild and poorly made ones can carry heavy metals.

Tomorrow: Switzerland and butterbur
the root with real trials for preventing migraines, and the liver risk that complicates it.

See you then.