But what are sulfites?
Sulfites are inorganic salt compounds that occur naturally in the human body and some foods. They are also added as preservative to other foods and many medications.
While most people have no issue with sulfites, a small percentage (an estimated 1% of people, and up to 5% of people who have asthma) of the population experience adverse effects after consuming them.
Where are they found?
And although red wine is high in sulfites compounds, white wines and sweet wines actually tend to have more sulfites than red.
Sulfites are also commonly added as a preservative (often under the name "sodium bisulfite, "potassium bisulfite," "sodium metabisulfite” or "sulphites") to dried fruits, packaged snacks and baked goods.
Are they safe?
The FDA currently has them on their "GRAS" list (meaning they give them a thumbs up for safety).
But they do acknowledge they may cause reactions in some people, and require foods with more than 10 sulfite parts-per-million to have a "CONTAINS SULFITES" label to alert consumers.
And, the FDA has banned their addition to fresh fruits and vegetables, which was once a common practice to preserve freshness and prevent browning. They also don't allow them to be added to foods with thiamin, as sulfites can destroy this B vitamin.
How do you know if you're sensitive to them?
Sensitivity may develop at any time in a person's life, and common symptoms include nausea, diarrhea, abdominal pains, low blood pressure, skin rashes and hives, and in rare severe cases, anaphylaxis.
These symptoms are much more common in people who have allergies and asthma.
And as far as the infamous "wine headache" goes, scientific data has never been able to prove sulfites are what causes wine headaches, and many point out that dried fruit contains about five times as many sulfites per serving compared to wine, and few people report headaches after their consumption.
What can I do to avoid them?
If you are sensitive to sulfites or simply wish to avoid them, look for the warning label and select products without it.