Is wine gluten-free? Yes, for the most part.
Wine is made from grapes, not grains. That’s good news for celiacs, those suffering from a digestive disease that makes them intolerant to gluten. May is Celiac Awareness Month so I thought it would be worth addressing this issue, especially since I’m asked about it occasionally.
The boom in gluten-free foods makes me wonder why there hasn’t been wine labeled to that extent, though that is akin to labeling fresh fruit as trans-fat free.
I’ve read The Wheat Belly and have followed various experts on this matter, not because I am intolerant of gluten, but 
because I try to avoid it when there are alternatives.
There are a couple of rare instances during the winemaking process where gluten may be introduced.
The first is if the vintner uses flour paste to seal joints of the oak barrels in which some wines are aged. This is a very rare practice, and almost unheard of with North American-made wines.
Second is the practice of fining wine to clarify it. Protein, such as egg whites, is usually used to fine wine, but wheat gluten may be used as well.
However, this is also rare, and even when used, the gluten that results in the wine is far less than the suggested safety threshold of 20 ppm because the point of a clarifying agent is to attract unwanted sediment in a wine and fall to the bottom of the tank where it is removed before bottling.
Therefore, it’s considered safe for most celiacs to drink wine. If you want to err on the side of safety choose wines that aren’t barrel aged, like most New Zealand Sauvignon Blanc, Italian Pinot Grigio and Riesling from just about any region in the world. For red wines, look for “unoaked” on the front or back label (that also works for many whites such as unoaked chardonnays).
Also, check with your doctor as this is not medical advice, just the drinking kind ;)
