Digestion and Wine
There is a reason that cultures around the world have made it a standard practice to enjoy wine along with food. Yes, it tastes wonderfully together - but there is a more encompassing reason. The ingestion of wine helps the food digest more easily.
The first thing to understand is how the stomach digests. When you eat food - let's say a 1" cube of steak - it doesn't plunk down into an empty stomach and just sit there, waiting to fall apart over time. Your stomach senses the presence of a food item and starts to release very powerful gastric acids. Those acids eat away at the food item, in this case the steak cube. The acids break down the steak into tiny protein and fat pieces, which then move through the stomach lining and into the blood stream. The blood moves those nutrients around through the body so they can reach their proper destinations. The fats might help the brain work more smoothly. The proteins might help to rebuild a leg muscle.
The issue is that a given food item is not 100% full of beneficial items. So for example turkey can have lipid hydroperoxides in it. So your body wants to take in the many great healthy aspects of turkey - but NOT take in the lipid hydroperoxides. The antioxidants naturally found in wines attack those lipid hydroperoxides, helping to break them down. So the end result is that the body does not have to deal with these harmful chemicals, and therefore is much less likely to get certain cancers as a result.
In addition to the very powerful action of the antioxidants in the wine, wine is also, naturally, an acidic beverage. The measure of an acid or base is called a "pH scale". A neutral measurement on a pH scale is 7. The further you get from 7 - either high or low - is an ever escalating thing. That is, if you go from 7 to 6, and then from 6 to 5, the 5 measurement is many times more acidic than the 6 was. It's like the Richter scale for earthquakes. Wine usually has a pH of around 3.5, which is very acidic. This high level of acidity helps to digest any food items sitting in it. A healthy stomach has an even higher level of acidity - usually around a pH of 1.5 to 2.5. So the wine helps to digest the food and stimulate the production of acid, while still being milder than the stomach's own "juices".
Some people who have weak stomach acids can have trouble properly digesting their food. The wine helps give them that extra "boost" to ensure their food is thoroughly digested.
Sources: Journal of Agricultural Food Chemistry
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Wine and Health