Does that glass of red wine you enjoy with dinner affect your testosterone levels? A study published in the Nutrition Journal suggests that it may help prolong testosterone’s effects by slowing down how fast the body metabolizes it.

Testosterone is broken down in the liver by a process known as glucuronide conjugation. The enzyme involved in this process is called UGT2B17, and belongs to the UDP-glucuronosyltransferase (UGT) enzyme family. Certain medications—such as non-steroidal anti-inflammatory drugs (NSAIDS) which include ibuprofen and naproxen—and flavonoids (catechins in certain teas) have been shown to inhibit UGT2B17 when used with testosterone, thus increasing the availability of testosterone in the body.

A British study evaluated the inhibitory nature of the common phenolic components found in wine on the activity of the UGT2B17 enzyme. In a laboratory setting, Carl Jenkinson, et al. measured initial testosterone levels and then added evaporated red wine at concentrations varying from 2-8%. The study’s aim was to determine the extent to which wine inhibited the UGT2B17 enzyme in the body.

One and two hours after the addition of the red wine, Jenkinson, et al. analyzed the remaining testosterone to determine if there was any increase in testosterone concentration. The results from this portion of the testing showed glucuronidation through the UGT2B17 enzyme was reduced to 10-70% of normal activity levels. The highest level of reduction was seen after measuring testosterone levels two hours after adding 8% red wine.

The main phenolic components of red wine were found to be gallic acid, chlorogenic acid, caffeic acid, and quercetin. The reduction of glucuronidation of testosterone by the UGT2B17 enzyme was statistically significant for quercetin and caffeic acid, which reduced glucuronidation activity by 28.01% and 78.9%, respectively.

Even though these results were statistically significant, it is difficult to know if they are clinically significant because we do not know to what extent testosterone concentrations were altered. The results are promising, showing that testosterone metabolism was reduced by a wide margin from what is normally seen. Perhaps one day practitioners may recommend a glass of wine with a patient’s testosterone supplement, or (more likely) a quercetin supplement, which could lead to better testosterone availability for patients.