What Are Sulfites and Should You Avoid Foods Containing Them?

Although often wrongly blamed for causing wine headaches and hangovers, sulfites aren't exclusive to wine. These compounds appear in a wide variety of food items, both naturally and as an added preservative. We often demonize sulfites, but is that fair, or have we been misinformed? What are sulfites really, and should we be avoiding them altogether? Let's uncover the facts about this common food and drink preservative.

What Are Sulfites, Exactly?

“Sulfites are chemical substances that contain a sulfur ion,” says Amy Davis, RD, LDN, a registered dietitian at FRESH Communications. These compounds naturally appear in some foods but are more frequently used as additives due to their preservative effects that inhibit bacterial growth. Sulfites also prevent foods from browning when exposed to oxygen (oxidation).

Sulfites vs. Sulfates

You’ve likely heard of sulfates and mistakenly confused them with sulfites. While both are sulfur-based, sulfates are not typically found in food.

“Sulfates are synthetic sulfur compounds that are mainly used in cleaning and personal care items,” explains Davis. These include products like shampoos, body washes, skincare items, laundry detergents, and more.

Are Sulfites Safe, or Should They Be Avoided?

Sulfites have earned their share of negative health attention over the years, but are they really as harmful as they’re made out to be?

“Sulfites are considered safe for most individuals when consumed in moderate amounts, but there are no specific health benefits linked to them,” explains Davis. This is true for both naturally occurring sulfites and the sulfite-based food additives that are generally recognized as safe (GRAS) by the U.S. Food and Drug Administration (FDA).

Christina Manian, RDN

Sulfite-related issues occur when someone is allergic or sensitive to the compound. People in this group often experience adverse reactions after consuming foods high in sulfites. “Symptoms can include headaches, skin rashes, swelling, stomach discomfort, and diarrhea. Asthmatic individuals seem to be particularly sensitive to sulfites,” explains Davis. Studies indicate that 3 to 10% of asthma patients may also be sensitive to sulfites.

There are additional general health concerns tied to sulfites worth considering. For instance, sulfites are not usually added to meat products because they deplete vitamin B1 before the body can absorb it. Moreover, a 2017 study discovered that sulfites could hinder the growth of four beneficial gut bacteria species, even in small quantities. While this effect might be lessened by consuming probiotic-rich foods (or supplements), it could still raise concerns for those focused on gut health, even for individuals without sulfite sensitivities.

Common Foods With Sulfites

Foods That Naturally Contain Sulfites

Interestingly, many of the foods naturally high in sulfites are also rich in probiotics, such as fermented foods like sauerkraut and kimchi. This is because sulfites are a natural byproduct of fermentation.

“Naturally occurring sulfites can also be found in foods such as black tea, peanuts, and certain vegetables like onions, lettuce, garlic, cabbage, kale, asparagus, leeks, chives, and broccoli,” says Davis. Additionally, plums, coconuts, strawberries, eggs, maple syrup, soy, and salmon are all natural sources of sulfites.

Foods With Added Sulfites

The list grows longer when we talk about processed foods that contain added sulfites. Wine is the most well-known example—though it’s also a natural source of sulfites since grape skins naturally contain them and wine is a fermented product.

You’ll also commonly find sulfites in various packaged foods, including “juices, sodas, jams, jellies, and pickled vegetables,” says Davis. They can also be present in canned vegetables, baked goods, soup or gravy mixes, dried fruit, snacks like trail mix or chips, pre-peeled potatoes, certain shrimp brands, frozen fruit or vegetables, and even molasses.

Should You Avoid Sulfites?

While most people don’t experience negative reactions after consuming sulfites, some individuals choose to avoid this compound entirely.

Reducing processed food intake, especially ultra-processed foods, is generally a wise decision, regardless of their sulfite content. However, the situation becomes more complicated when it comes to natural sources of sulfites.

In my professional opinion, if you don’t have an adverse reaction to sulfites, the health benefits of natural sulfite sources—fruits, vegetables, and protein options like eggs and salmon—far outweigh the minimal health risks linked to this compound.

Mindful Ways to Avoid Sulfites

For anyone looking to eliminate sulfites due to a sensitivity or allergy, the most straightforward approach is to “reduce intake of foods that typically contain high levels of sulfites,” advises Davis. This may include choosing low-sulfite or no-added-sulfite wines (some good options include Avaline, Bonterra, Terramore, and Frey Vineyards). It’s also suggested that red wine may have fewer sulfites than white wines, although there is not enough research to confirm this claim (nevertheless, it could be worth testing at home if you're not allergic).

It’s essential to pay closer attention to ingredient lists—the only way to determine whether a food product contains sulfites is by carefully checking the ingredients. Sulfite additives come in many forms, but the most common include: potassium bisulfite, sulfur dioxide, sodium bisulfite, sodium sulfite, potassium metabisulfite, and sodium metabisulfite.

If you need to avoid even the healthiest foods that contain sulfites due to health reasons, it might help to create a list of common offenders and post it on your fridge or another visible spot in your kitchen. This can help prevent accidentally consuming sulfite-rich foods and serve as a useful reminder when you’re preparing grocery lists.

While some processed foods high in sulfites may be difficult to replace, more alternatives are appearing on grocery store shelves (though again, this will require reading labels carefully). Alternatively, you could try making typically sulfite-laden foods at home: jams, pickled vegetables, baked goods, gravies, and trail mix, for example.

The Bottom Line on Sulfites

Although sulfites may not pose a significant health risk to everyone, they can cause adverse reactions in those with allergies or sensitivities. Additionally, emerging studies suggest that sulfites may interfere with vitamin B1 absorption and impact gut microbiome health, potentially motivating even those without allergies to reduce their intake. Whatever the reason, there are numerous ways to cut back on sulfites, such as understanding natural sources and carefully reading food labels.