Kwao Krua

Tubers of Thai Medicine

Written by Kamal Patel
Last Updated:

Two plants have been added to Examine's database, both of which are traditional Thai medicines and both of which have their tubers used for medicine. Their bioactivities are interesting but for the most part still being researched, but their existence and usage is somewhat poetic.

The two herbs in question are the confirmed estrogenic Pueraria Mirifica and androgenic Butea Superba. These tubers are called White Kwao Krua and Red Kwao Krua respectively, are visually similar unless otherwise disturbed (in which case, Butea Superba secretes a red liquid owing to its common name), and both have a history of usage in Thai medicine for revitalizing older individuals (of which the benefits are gendered; 'Kwao Krua' in general is a term given to revitalizing agents it seems while White and Red are recommended for women and men respectively).

Both of these tubers appear to actually contain compounds that act directly on the receptors in question, circumventing the need to actually increase the hormone by acting as phytohormones themselves (phytoestrogens are well talked about, phytoandrogens are next to never talked about).

White Kwao Krua has a cluster of basic phytoestrogens including soy isoflavones in high quantities, yet these are not the reason for its estrogenicity. Estrogenic effects of this tuber come from a class of molecules called Chromenes; the 'main' chromene, Miroestrol, has been noted to be about a quarter as potent as the most powerful endogenous estrogen (17β-Estradiol). The related compound, Deoxymiroestrol, is about ten-fold more potent than Miroestrol and likely more potent than 17β-Estradiol itself on a weight basis (they haven't been directly compared, but the math leads to that conclusion). It has been shown numerous times to have estrogenic effects in both rats and primeapes, although the human studies currently using White Kwao Krua are less than optimal in study design.

Butea Superba (Red Kwao Krua) is not as well researched. It shares similar historical renown as White Kwao Krua except for men, but the androgenic molecule has not yet been confirmed; the androgenic effects per se have been confirmed in mouse and rat models of both genders and seem to work via the receptor itself rather than increasing testosterone. No study has attempted to compare the potency of Butea Superba on the receptor against more well known agonists such as testosterone itself (so such a nice conclusion on 'X as potent as testosterone' cannot be made right now).

As for the third Kwao Krua, known as Black Kwao Krua and bearing the botanical name of Mucuna collettii (not Mucuna Pruriens; totally different plant) is incredibly underresearched and no conclusions can be made on the third member of this party at this time.

Overall, we have two hormonally active tuber vegetables that are also common supplements; their history is intertwined in Thai medicine and they both appear to have efficacy in hormonal signalling. Their existence is somewhat poetic, and their bioactivities are understudied but potentially worth looking into more.