Formulation:

The existing clinical trials have studied a variety of Dioscorea species and formulations. Powdered extractions of D. alata, D. batatas, D. nipponica, and D. esculenta were derived from the tubers or rhizomes and often processed into capsules or tablets before use.^{[10][11][12][13][14][15]} However, one study on D. villosa incorporated it into a vegetable-based cream that was applied topically.^[16]

Though the studies on traditional Chinese and multiherbal preparations included a species of Dioscorea, the specifics on the species and formulation of Dioscorea were not always provided or clear.^{[17][18][19][20][21][22][23]}

Range of dosages studied:

Human studies investigating various Dioscorea species have used a range of doses, formulations, and durations. Tuber and rhizome extractions of D. alata, D. batatas, D. bulbifera, D. esculenta, and D. villosa have all been studied in dosages ranging from 24 to 2,000 mg per day. Treatment durations have ranged from 4 to 52 weeks.^{[10][11][16][24][12][14]}

Other Considerations:

In the US, there are several species listed in dietary supplements, which include D. bulbifera, D. hypoglauca, D. japonica, D. nipponica, D. makino, D. opposita, D. villosa, and D. polystachya. However, it should be noted that many supplement labels do not specify the species used and tend to rely on common names (e.g., “wild Mexican yam”) when this information is available at all.^[25]