# What is Sulfate Intolerance and How to Detect It Sulfate intolerance (also called sulfite intoler
Headache After a Glass of Red Wine or a Piece of Chocolate
Many people experience this, but few suspect what's really behind it. Histamine, tannins, or caffeine are most commonly blamed – yet for some people, the cause lies somewhere entirely different. Sulfite intolerance, meaning sensitivity to sulfates and sulfites present in food, remains one of the most overlooked causes of recurring migraines, and yet it can significantly affect everyday quality of life.
Before we look at what sulfite intolerance actually is and how it manifests, it's important to distinguish between two terms that are often confused in practice. Sulfates are salts of sulfuric acid, while sulfites are salts of sulfurous acid. Both groups of substances occur naturally in a range of foods and beverages, but sulfites are also widely used as preservatives. In the context of food intolerance, sulfites are the primary concern, though in everyday speech and even in the literature, both terms are sometimes used interchangeably. What matters for readers of this article is that both groups can trigger unpleasant reactions in sensitive individuals – and migraine is among the most common.
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Why Red Wine and Chocolate?
Red wine is almost the symbolic example in this regard. It contains naturally occurring sulfites as a by-product of fermentation, and producers also add sulfur dioxide as a preservative to prevent oxidation and extend shelf life. White wines and sweet wines typically contain more sulfites than red wines, yet red wine is more frequently associated with migraines – probably because it combines sulfites with histamine, tannins, and tyramine, a whole range of potentially problematic substances all at once.
Chocolate is in a similar position, though for slightly different reasons. Cocoa itself doesn't contain high amounts of sulfites, but chocolate products – especially milk and white chocolate – may contain additives that include sulfites or their precursors. Moreover, chocolate is rich in tyramine and phenylethylamines, substances that also trigger headaches in sensitive individuals. When sulfite intolerance is added to the mix, the result tends to be unpleasantly reliable: a headache arrives almost every time.
Beyond wine and chocolate, other common dietary sources of sulfites include dried fruit, processed meat products, canned vegetables, vinegar, beer, as well as certain medications and dietary supplements. Someone who complains of recurring migraines with no apparent cause may not even consume wine or chocolate – a daily portion of dried apricots or a slice of salami for a snack may be enough.
Imagine Jana, a thirty-year-old teacher who suffers from migraines every weekend. She leads a healthy lifestyle, exercises, and doesn't drink alcohol. It's only after keeping a detailed food diary that she discovers she eats dried fruit as a snack every Friday evening while watching a film – and that's where the problem lies. Dried fruit, particularly apricots, prunes, and raisins, are among the foods with the highest concentrations of sulfites of all. Such stories are not exceptional, and healthcare professionals are drawing attention to them with increasing urgency.
How Sulfite Intolerance Works in the Body
Under normal circumstances, the human body is able to metabolise sulfites using the enzyme sulfite oxidase. This enzyme depends on molybdenum, a trace element, and its sufficient activity is key to safely processing dietary sulfites. In people with intolerance, the activity of this enzyme is reduced, meaning sulfites accumulate in the body for longer than is healthy. The result is a variety of reactions – ranging from mild discomfort to serious symptoms.
Migraine is just one of the possible manifestations. Other typical symptoms of sulfite intolerance include hives, asthma attacks, stomach cramps, diarrhoea, skin flushing, and a sensation of a racing heart. Asthma is historically the best-documented reaction to sulfites – the U.S. Food and Drug Administration (FDA) estimates that approximately 1% of the population is sensitive to sulfites, with this figure potentially being significantly higher among asthmatics, estimated at up to 5–10%.
Migraine as a symptom of sulfite intolerance is, however, less scientifically studied than the asthmatic reaction. The mechanism is not fully understood, but it is thought that sulfites may influence the release of neurotransmitters and cause vasodilation – the widening of blood vessels in the brain, which is one of the key processes in the onset of migraine. Sulfites may also interact with histamine and impair its metabolism, thereby indirectly intensifying a migraine attack even in people who would not otherwise experience histamine intolerance significantly.
Individual sensitivity thresholds also play an important role. Not every person with reduced sulfite oxidase activity will react to every glass of red wine. It depends on the total amount of sulfites consumed on a given day, the overall state of the body, stress levels, sleep deficit, and what else was eaten that day. A migraine then arrives as the result of exceeding a kind of personal tolerance threshold – and it is precisely this variability that makes diagnosis difficult.
As neurologist and headache specialist Peter Goadsby once said: "Migraine is not just a headache. It is a complex neurological disorder with many triggers, the combination of which differs in every patient." This complexity is exactly why sulfites as a trigger so easily escape notice – on their own they may not be sufficient, but in combination with other factors they can be the final link in the chain.
How to Identify the Intolerance and What to Do About It
Diagnosing sulfite intolerance is not straightforward. There is no standardised blood test that can reliably confirm it. The most common approach combines a food diary, an elimination diet, and possibly a provocation test under medical supervision. A food diary is the most accessible and at the same time a very effective tool – it simply involves carefully recording what and when a person eats, and observing whether and when migraines or other symptoms appear.
An elimination diet involves temporarily removing all foods with a high sulfite content for approximately two to four weeks. If symptoms subside, this is a strong indicator that sulfites are playing a role. By gradually reintroducing individual foods, specific triggers can be identified and a personal tolerance threshold established.
When reducing sulfite intake, it is useful to know where they most commonly hide:
- Dried fruit (apricots, prunes, raisins, figs) – one of the richest sources
- Wine and beer – naturally occurring and added sulfites
- Processed meat products – sausages, salami, hot dogs
- Canned and pickled vegetables – especially in vinegar or brine
- Ready meals and powdered soups – sulfites as a preservative
- Prawns and other seafood – sulfites are added to preserve colour
In the European Union, manufacturers are required to declare sulfites on the label if their content exceeds 10 mg/kg or 10 mg/litre. The labelling may appear in various forms: sulfur dioxide (E220), sodium sulfite (E221), potassium metabisulfite (E224), or sodium metabisulfite (E223). Reading labels thus becomes a daily necessity for people with sulfite intolerance.
Beyond dietary elimination, the role of molybdenum as a dietary supplement that could support the activity of the enzyme sulfite oxidase is sometimes discussed. Scientific evidence is still limited, and it is always advisable to consult a doctor or nutritional therapist before taking any supplement. Similarly, vitamin B12 and riboflavin (vitamin B2) have some support in the literature as substances that may help with migraine prevention in general – the Czech Pain Society recommends an individualised approach to the treatment and prevention of migraines, as triggers vary considerably between patients.
It is also important to note that sulfite intolerance is not an allergy in the immunological sense. A classic food allergy involves an immune system reaction mediated by IgE antibodies and can be life-threatening. Intolerance, by contrast, is a metabolic inability to properly process a particular substance – it is unpleasant and restrictive, but is generally not immediately dangerous. This distinction is also important when communicating with doctors, who may evaluate standard allergological tests for sulfites as negative without this ruling out intolerance.
Interest in food intolerances in general has been growing in recent years, including in professional circles. A growing number of doctors and nutritional specialists are recognising that many chronic complaints – from migraines to skin problems to digestive issues – may originate in everyday diet rather than in serious illness. For people who have spent years searching for the cause of their migraines and undergoing various tests without a clear result, identifying sulfite intolerance can be a genuine breakthrough. It is not a diagnosis that requires complex treatment – in many cases, awareness, attention, and a willingness to change a few dietary habits is sufficient. And it may not be necessary to give up a glass of red wine forever – it may simply be unwise to combine it with a dinner of dried fruit and smoked meats.
