Cordyceps

Cordyceps arrived in Western supplementation on the back of a 1993 Chinese distance-running story and has been sold on that anecdote ever since. The actual evidence is more modest but not empty, and the biggest practical issue is that most products do not contain what buyers think they do.

Three things get sold as cordyceps. Wild Cordyceps sinensis, the caterpillar fungus from the Tibetan plateau, is one of the most expensive biological commodities on earth and is essentially never what is in a capsule. CS-4 is a fermented mycelial strain isolated from it, grown in liquid culture — a legitimate ingredient with its own trials. And a great deal of retail product is mycelium grown on grain, dried and milled with the grain still in it, which is mostly starch with a modest beta-glucan content and little cordycepin. Cordyceps militaris, by contrast, is cultivated on a solid substrate, produces actual fruiting bodies, and contains far higher cordycepin — it is the sensible purchase.

Mechanistically, cordycepin is a 3-deoxyadenosine analogue that appears to act on adenosine receptors and support ATP regeneration, while cordyceps polysaccharides improve mitochondrial efficiency and antioxidant enzyme activity in animal models. Human exercise trials in older adults and in trained cyclists show improvements in VO2 max, ventilatory threshold and time to exhaustion at 1-3 g/day of CS-4 or a militaris-containing blend after three weeks, with effect sizes in the small-to-moderate range. Trials in young trained athletes have been less consistent. Beyond performance, there is preliminary work on fatigue, immune modulation and libido, none of it conclusive.

Tolerability is good. The main cautions are autoimmune disease, given immune stimulation, and anticoagulant therapy, given mild antiplatelet activity.