Why red wine gives some people headaches?

A recent study from the University of California, Davis, published in the journal "Scientific Reports," has shed light on a long-standing mystery that has perplexed both consumers and scientists: Why does red wine cause headaches in some individuals? Traditionally, sulfites, histamines, or simply an excess of alcohol have been cited as likely culprits. However, this new research suggests that quercetin, a healthy polyphenol found in red wine, might be responsible for slowing down the metabolization of alcohol in certain people, leading to discomfort and headaches.

Quercetin: A Healthy Flavanol

Quercetin is a type of polyphenol known as flavanol, naturally present in fruits and vegetables, including grapes. This antioxidant, also available in supplement form, has been linked to several health benefits attributed to red wine.

How Can a Healthy Component of Wine Cause Headaches?

The process of alcohol metabolization in the human body is a two-step sequence. First, alcohol is converted into acetaldehyde by an enzyme called alcohol dehydrogenase (ADH) in the liver. Then, another enzyme, aldehyde dehydrogenase (ALDH), breaks down acetaldehyde into acetate. Excessive and rapid consumption of alcohol can lead to an accumulation of acetaldehyde before it can be converted, resulting in adverse effects. However, some people experience these conditions with just a small amount of red wine, including many individuals of East Asian descent.

In the study, Devi and her colleagues investigated how various polyphenols present in red wine interact with the enzymes that metabolize acetaldehyde. They discovered that quercetin showed the highest inhibitory activity. "When quercetin enters the bloodstream, the body converts it into a different form called quercetin glucuronide," explained Andrew Waterhouse, a wine chemist and the study's lead author. "In this form, it blocks the metabolization of alcohol."

As a result, individuals may end up accumulating toxic acetaldehyde, leading to headaches, facial flushing, and an overall unpleasant experience.

Scientists at the Headache Center plan to launch the next phase of this research. The goal is to compare red wines containing high amounts of quercetin with those having very little, to test their theory about red wine-induced headaches in people. This clinical trial is funded by the Wine Spectator Scholarship Foundation, dedicated to supporting education in wine, food, and hospitality industries.

Waterhouse and Devi acknowledge that there are still many unknown factors behind red wine-induced headaches, particularly why some people seem to be more susceptible. "If our hypothesis is correct, then we will have the tools to start addressing these important questions," Waterhouse stated.