Kudzu Extract Not Found to Intensify Alcohol Intoxication


A placebo-controlled study tested the assumption that isoflavones contained in kudzu extract could lengthen or strengthen the effects of alcohol, thereby postponing the urge to take the next drink. Participants’ consumption response remained unchanged by the kudzu extract in spite of a short duration of rise in plasma concentration of ethanol in the initial 10 to 15 minutes following alcohol consumption. Thus the study’s assumption was not proven and the mechanism of action of kudzu extract is still unknown.


Kudzu is a vine belonging to the pea family. Several clinical and preclinical study reports have shown that kudzu root extract in achieving substantial decrease in alcohol consumption. A human trial in 2005 recorded a significant reduction in beer drinking when the participants were given the extract of kudzu root, which is rich in isoflavones, before drinking. The possible reason for this effect was tested but the correct mechanism has not been discovered yet. Hence, this study was designed to check whether kudzu extracts affected post-alcohol behavior involving psycho-physiological cognition and why these occurred.


  • Capsules of either kudzu or placebo were administered to 12 healthy volunteers for a study period of nine days.
  • On the eighth day, participants were required to drink three cups of orange juice about two to two-and-a-half hours after having the capsules; while on the ninth day they were given three cups of either a low-dose or a high-dose alcoholic drink after similar pretreatment with capsules.
  • Concurrently, physiological (heart rate, body sway, physical stance) and behavioral (feelings of clumsiness, slurred speech, confusion) parameters were recorded and periodic blood sampling was done for ethanol concentrations in the plasma.
  • A second round of similar treatment and alcohol/orange juice ingestion was carried out after a one-month “washout” period.


  • No effect was seen due to pretreatment with kudzu on dizziness, body sway and lesser cognitive reflex.
  • Kudzu increased heart rate and skin temperatures as compared to placebo with readings of 77.3 bpm versus 66.7 bpm, and 30.7 C versus 28.8 C, respectively.
  • Pretreatment with kudzu was seen to increase ethanol levels in plasma of the high-dose alcohol group for a short period.

Shortcoming/next steps

The sample size in the current study was inadequate. The singular effects of kudzu (without a simultaneous drink) were not investigated in detail. Future research using “magnetic resonance spectroscopy” to measure the change in concentration of alcohol due to kudzu treatment may give some clues as to the mechanism of kudzu extract’s effect.


The earlier presumption of kudzu adding to the intoxication or to the compromised psychological parameters of alcohol has been dismissed now. A dose-response relation between alcohol and kudzu is suggested by recurrent findings of elevation in heart rate, skin temperature and plasma ethanol level with kudzu pretreatment at higher alcohol doses. However, the present study did not contribute anything new with regard to understanding the relationship between the role of kudzu root extract and the intake of alcohol. The study authors believe that until more advanced studies are performed on this subject, “the mechanism of action of this herbal preparation to reduce alcohol consumption remains elusive.”

For More Information:

Kudzu Extract Treatment Does Not Increase the Intoxicating Effects of Acute Alcohol in Human Volunteers

Alcoholism: Clinical and Experimental Research, April 2011

By David M. Penetar; Robert R. MacLean; Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School, Belmont, Massachusetts

*FYI Living Lab Reports Are Summaries of the Original Research.
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