Studies have shows that symptoms of intolerance in drinkers were more frequently reported after drinking red wine than white wine. Wine contains small amounts of proteins, which mainly come from grapes but can also be introduced by bacteria and yeast.
One of the proteins found in wine is the lipid transfer protein (LTP), which has been shown to come from grapes and is a recognised allergen. It is found on grape skins and in the must during the fermentation of red wine. LTP can sometimes lead to serious symptoms such as anaphylaxis. However, it has been shown that drinking wine on a regular basis can lead to the development of tolerance to LTP and reduce the risks. In contrast, the must used to produce white wine is fermented without grape skins. This may explain why red wine causes more intolerance symptoms more frequently than white wine.
Other proteins that have also been discussed as potential allergens, such as thaumatin-like proteins, endochitinases, and glucanases, are present in equal amounts in red and white wine.
In addition to these allergens, other ingredients or chemicals involved in wine production, such as sulfites or the biogenic amines of histamine and tyramine, may also cause reactions.
It is proposed that the mechanism of general intolerance to wine could be as a result of the following:
- polar and hydrophobic ingredients in wine could be dissolved in alcohol, thereby promoting their absorption into the body;
- alcohol promotes the permeability of the intestinal mucosa, which could increase the absorption of wine ingredients;
- alcohol-induced vasodilation could also be responsible for some symptoms of wine intolerance, such as skin flushing;
- alcohol inhibits the enzyme diaminooxidase, which degrades histamine and other biogenic amines. This would increase histamine concentrations and could lead to symptoms such as vascular dilation in the nose region
In the Mainz study 2012, only 3 out of 30 participants with self-reported wine intolerance and 6 out of the total of 68 wine-intolerant individuals identified in the study additionally reported grape intolerance, supports the assumption that wine intolerance is very rarely caused by true allergy to grapes.
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