Researchers have found that a natural flavonol compound in red wines can interfere with the metabolism of alcohol which leads to a headache.

The University of California team in Davis say it's all about quercetin, which is naturally present in many fruits and vegetables, including grapes. It's a healthy antioxidant that is even available in supplement form—but when mixed with alcohol, it can be problematic.

"When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide," said Professor Andrew Waterhouse. "In that form, it blocks the metabolism of alcohol."

They also report, in the study published in the journal Scientific Reports that different wines had different amounts of the pain-inducing flavanol depending on how much sunlight the grapes absorbed.