There are several hypotheses regarding the causes of "red wine headaches." According to scientists, one leading theory is that some people lack the enzymes needed to break down the high concentrations of certain chemicals commonly found in grapes, particularly in the skin, writes IFLScience.

Red wine ferments with the grape skins, unlike white wine, which is produced after removing the skins, notes Фокус. As a result, red wine contains higher amounts of compounds found in the skins, particularly histamine and tannins.

High levels of histamine in the blood are known to dilate blood vessels and cause headaches, while tannins can activate neurotransmitters associated with pain. Thus, claims that red wine can trigger headaches do have some basis, although definitive evidence is still lacking.

Some people who suffer from headaches also blame sulfites, preservatives added to prevent fermentation. However, scientists note that sulfites are present in many foods and drinks, and some sources suggest that white and sweet wines may contain several times more sulfites than red wine.

Quercetin is mainly found in grape skins, which is why red wines contain significantly more of it than white wines. Interestingly, quercetin develops when grapes are exposed to sunlight during growth, a process usually associated with higher-quality wines. This may mean that more refined and expensive wines are more likely to trigger headaches than cheaper ones.

However, scientists have not yet determined why some people are more prone to red wine headaches than others. They intend to continue their research to find the answer to this question.

Approximately 8% of the world’s population, mainly of East Asian descent, have a deficiency in the ALDH2 enzyme, which can cause headaches and flushing after drinking wine. Even individuals with a mild ALDH2 deficiency may experience increased acetaldehyde levels from the additional quercetin in red wine, pushing it above the threshold that triggers headaches.