Cordyceps without the 'worm'

Cordyceps without the 'worm'

Herbs used in traditional Chinese medicine (TCM) come either from plants, animals or minerals.

Wild cordyceps, however, are a hybrid of plant and animal sources, which is why the herb's Chinese name of dongchong xiacao is loosely translated as "winter worm, summer grass".

The capless mushrooms are grown from caterpillars at high altitudes of 4,500m, with those from Tibet and Qinghai in China known to be of premium quality, said Ms Daphne Ong, a TCM physician in Eu Yan Sang's department of product development.

When the cordyceps spores land on the body of the batmoth caterpillar, the spores feed on the nutrients from the animal.

Mycelia, or mushroom spawn, invades and eventually replaces the host tissue, causing the caterpillar to die. What is left is the exoskeleton of the caterpillar, Ms Ong added.

The fungus then sprouts from the head of the caterpillar, like a grass in summer.

They are collected in the summer months, from April to August, by harvesters who go down on their hands and knees to dig them from the soil, she said.

Cordyceps are ideally harvested before the sporangium (case or sac in which spores are produced) matures to release spores, or else the caterpillar will be so shrivelled that it has little market value.

To ensure that the caterpillar is still plump and big, the herb is dug out after the sporangium has barely sprouted into a shoot.

The irony is that doing so reduces the number of mature cordyceps in the wild that can produce spores to infect other caterpillars, said Ms Ong.

Consumers should note that the bigger and fuller the body of wild cordyceps, the pricier it will be.

Also look out for the presence of four prominent pairs of legs on the herb to check if it is authentic.

Cordyceps are among the most prized herbs in TCM and demand for it far outstrips its supply.

The challenge of harvesting wild cordyceps prompted researchers to reproduce them in the laboratory, with attempts to make them as similar to the wild herb as possible.

Different strains of cordyceps were isolated in the laboratory with the hope of finding one suitable for replication.

Many of the earlier cultures obtained in China, such as Cs-4, and marketed as cordyceps turned out to be incompatible with the wild ones when genetically analysed.

It was only in 2001 that scientists confirmed one strain, the hirsutella sinensis, has more than 99 per cent genetic similarity to wild cordyceps. The China Food and Drug Administration has certified that hirsutella sinensis is the anamorph (the asexual stage) of cordyceps sinensis, one of more than 400 species of cordyceps.

Producing cordyceps through biotechnology makes the product suitable for vegetarians, as no caterpillars are involved.

Ms Ong said in producing cultivated cordyceps, the manufacturing plant makes sure that factors, such as temperature, humidity and water, mimick those in the wild.

The product, fermented in a proprietary nutrient broth, is then freeze-dried to increase its purity and active ingredients.

Eu Yan Sang sells seven grades of wild cordyceps, which cost from $1,998 per tael (37.5g) to more than $4,000 per tael.

In contrast, a bottle of 90 capsules of cordyceps, made from 100 per cent hirsutella sinensis, costs $113.

joanchew@sph.com.sg


This article was first published on Oct 23, 2014.
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