Sodium bisulfite is generally safe to eat for most people. The FDA classifies it as “Generally Recognized as Safe” (GRAS) when used according to good manufacturing practices, and your body has a built-in enzyme specifically designed to break it down. That said, it can trigger serious reactions in a small percentage of people, particularly those with asthma.
How Your Body Handles Sulfites
When you consume sodium bisulfite, your body converts it from sulfite into sulfate, a relatively nontoxic compound that’s easy to excrete. An enzyme called sulfite oxidase handles this conversion, and it’s the same enzyme your body already uses to process sulfur-containing amino acids from everyday protein sources like meat, eggs, and beans. For most people, this system works efficiently and without issue.
The joint WHO/FAO expert committee on food additives has set the acceptable daily intake for sulfites (as a group) at 0 to 0.7 mg per kilogram of body weight, expressed as sulfur dioxide. For a 150-pound person, that works out to roughly 48 mg per day. This threshold includes all sulfite-type additives combined, not just sodium bisulfite.
Where You’ll Find It in Food
Sodium bisulfite belongs to a family of sulfite preservatives that prevent browning and inhibit bacterial growth. You’ll encounter them across a wide range of processed foods, though concentrations vary significantly.
Foods with the highest sulfite levels (over 100 parts per million) include wine, dried fruits (except dark raisins and prunes), bottled lemon and lime juice, grape juices, molasses, sauerkraut, and pickled cocktail onions. A step below that, in the 50 to 99 ppm range, you’ll find dried potatoes, fruit toppings, gravies, maraschino cherries, and wine vinegar.
Lower but still measurable amounts (10 to 49 ppm) show up in foods you might not expect: fresh shrimp, frozen potatoes, fresh mushrooms, maple syrup, cornstarch, guacamole, various cheeses, pickles, and imported jams and soft drinks. The FDA requires food labels to declare sulfites whenever the finished product contains 10 ppm or more, so checking ingredient lists is straightforward.
FDA Restrictions on Its Use
While sodium bisulfite carries GRAS status, the FDA imposes specific limits. It cannot be used on fruits or vegetables intended to be served or sold raw, or presented to consumers as fresh. This rule dates back to the 1980s, when sulfite use on restaurant salad bars was linked to severe reactions. It’s also banned from use in meats and in foods recognized as a source of vitamin B1, because sulfites destroy that vitamin on contact.
Who Reacts to Sulfites
The main safety concern with sodium bisulfite is sulfite sensitivity, which predominantly affects people with asthma. Challenge studies estimate that about 3.9% of asthmatic patients react to sulfites, with steroid-dependent asthmatics at the highest risk. In the general population without asthma, sensitivity is considerably rarer.
Reactions can range from mild to life-threatening. The most common response is bronchoconstriction, a tightening of the airways that feels like an asthma attack. But sulfite-sensitive individuals have also reported skin reactions like hives and flushing, gastrointestinal symptoms including abdominal pain and diarrhea, drops in blood pressure, and in rare cases, full anaphylaxis. These symptoms can appear alone or in combination, and severity varies from person to person and even from one exposure to the next.
Long-Term Safety Data
Animal toxicity studies using high oral doses of sodium bisulfite found hyperplastic changes in the stomach lining, meaning cells multiplied faster than normal. These effects occurred at doses well above what humans typically consume through food. Clinical studies involving direct oral exposure in humans reported no adverse effects at normal dietary levels.
Some laboratory tests have raised questions about whether sodium bisulfite could damage DNA. However, the chemistry of sulfites makes these results hard to interpret cleanly. In solution, sodium bisulfite exists in a shifting balance with several related compounds (sulfur dioxide, sulfite, metabisulfite), so isolating the effect of any single form is difficult. Safety reviews have concluded that the genotoxicity data doesn’t present a clear or consistent concern.
Practical Takeaways for Sulfite-Sensitive People
If you have asthma and suspect you react to sulfites, the most reliable strategy is reading labels carefully. Look for any of the common sulfite additives: sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite, potassium metabisulfite, and sulfur dioxide. Wine and dried fruits tend to be the biggest sources, so those are worth paying attention to first.
Keep in mind that foods with fewer than 10 ppm of sulfites don’t require label disclosure, so trace amounts can still be present in unlabeled products. Restaurant meals are another blind spot, since sulfites may be used in food preparation without being listed on a menu. If you’ve had a confirmed reaction to sulfites in the past, carrying emergency medication and communicating your sensitivity when eating out becomes important.