Very simply, sulfites are a preservative to wine, which is a volatile food product.
Wineries have been using sulfur around wine for a long time, as far back as the Roman times. Back in Roman times, winemakers would burn candles made of sulfur in empty wine containers (called Amphora) to keep the wines from turning to vinegar. Sulfur started to be used in winemaking (instead of just cleaning wine barrels) in the early 1900’s to stop bacteria and other yeasts from growing. It also helps in the extraction of pigments in wine, making red wines ‘redder’.
About 5-10% of people with asthma have severe sulphite sensitivity and thus the US requires labeling for sulfites above 10 parts per million (PPM). Sulfur is on the rise as a concern among humans as a cause of health problems (from migraines to body swelling) because of its prevalence in processed foods.
Commercially purchased wines can have up to 350 PPM, while organic wines must ring in less than 100 PPM.
While Sulphites are necessary to preserve wine, Wine Butler Craft wine contains 30-70 ppm (parts per million) of sulphite, very low content even by standards for organic wines.