It’s happened to the best of us and, unfortunately, we all know the feeling: Waking up the next morning, feeling like death warmed up and swearing you’ll never drink again. But what exactly is a hangover and what in wine causes hangovers?

For those who don’t know, common features of hangovers include headaches, nausea, fatigue, dehydration and weakness, even mild depression. I must admit I didn’t realize hangovers are that complex until I started to research them. It gets a little technical, I know, but hang in there – it’s pretty interesting!

The most common cause of a wine hangover is dehydration. Alcohol causes the body to lose water through a complex pathway, resulting in the brain temporarily shrinking. This puts the membranes under strain, causing a headache. This goes hand in hand with a very dry mouth. Furthermore, alcohol causes glycogen (your medium-term energy store) to be converted into glucose and excreted along with salts and minerals, causing you to feel tired the next day. Are you ready to open the next bottle of Chenin yet?

Another major cause of hangovers is biogenic amines, specifically histamine, a chemical we usually associate with allergic reactions. Almost all alcoholic beverages contain some histamine, especially red wine, as it is made from whole grapes. Some people are more sensitive to histamine than others, which can lead to allergic reactions. Symptoms may vary from rosy cheeks to bad headaches. This has nothing to do with the vast amount of wine they knocked back the previous night, of course… There are quite a few factors that can influence the histamine content of wine, and most of them are related to the microbial health of the wine. So, it is very possible that the red wine from one producer will be fine while the same variety from another producer will give you a splitting headache.

And then there is acetaldehyde, which is a by-product of the liver breaking down alcohol. The body can break down small quantities of acetaldehyde, but it cannot metabolize large quantities acetaldehyde, which adds to your hangover. Interesting to note here is that acetaldehyde is closely related to formaldehyde, the preservative that scientists use to store dodgy organs in jars. That really makes you reach out to your wine rack, doesn’t it?

Next is a group of molecules called congeners, which is commonly found in dark-colored drinks like red wine, brandy and whiskey. Very little is known about this chemical group, but apparently it is not very good for us, hence the hangovers.

Interestingly, in my research for this article, I found no mention of sulfur – one of the most popular culprits on which hangovers are pinned. Now you know what happens on the odd occasion when you lose the plot. Having said that, I still believe that moderate wine consumption will definitely add quality to your life and health. Cheers!

Boela Gerber is the winemaker of Groot Constantia wine estate in South Africa. This blog was originally published on www.conca.co.za.