Wine · 3.4
Sulfites, headaches, and what is actually established
All wine contains them, sensitivity is real and respiratory, and the headache attribution is not supported by the evidence.
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Sulfites are blamed for wine headaches more often than any other component, and the evidence does not support it. What follows separates what is established from what is not, and stops where the record stops.
What they are and why they are there
Sulfur dioxide is an antimicrobial and an antioxidant. It stops unwanted organisms, prevents browning, and keeps a wine from oxidising in the bottle. Sulfur has been burned in wine barrels for this purpose since antiquity.
Every wine contains some, whether or not any was added, because yeast produce sulfites during fermentation. Wine with no sulfites at all does not exist; wine with none added does.
What the label means
In the United States a wine must declare sulfites above ten parts per million, which nearly all wine exceeds. The declaration is a statement about a threshold rather than about a quantity, and it appears on almost every bottle regardless of how much was used.
Levels differ by style. Dry reds generally need least, whites more, and sweet wines most of all, because residual sugar is what a stray yeast would ferment in the bottle. Legal maximums differ by jurisdiction and by category.
Who is actually sensitive
Sulfite sensitivity is real and it is uncommon. Where it occurs it appears mainly in a subset of people with asthma, and it presents as a respiratory reaction rather than as a headache.
Dried apricots carry several times the sulfite concentration of wine and do not produce the effect people attribute to wine, which is the observation that undermines the popular account most directly.
What else is in the glass
Alcohol itself, which dilates blood vessels and is a diuretic. Biogenic amines such as histamine and tyramine, present in fermented foods generally. Tannins and other phenolic compounds. And the congeners produced during fermentation.
Each has been proposed and none has been established as the cause of the specific complaint people describe.
Where the research currently is
A hypothesis published in 2023 proposed that a flavanol found in grape skins could interfere with the enzyme that clears a by-product of alcohol metabolism, which would produce symptoms in some people at modest doses.
It is a hypothesis. Its authors described it as requiring clinical testing, and it has not yet been confirmed or refuted. It is mentioned here as the current state of an open question rather than as an answer.
What this entry is not
It is not medical advice and it makes no claim about whether wine is good or bad for anybody. If drinking wine reliably makes you feel unwell, that is a matter for a doctor rather than for a festival journal, and nothing here should be read as encouragement to test it.
If you want to work out your own variable
The useful observation is that sulfite content varies with style in a known direction. Somebody who reacts to dry red wine and not to sweet white is reacting to something that runs opposite to the sulfite gradient, which rules the sulfites out for them personally.
Dose, speed, food and water are the variables most people have never controlled, and they are larger than anything discussed above.
The organic and natural labels
Rules differ between countries in ways that surprise people. Wine certified organic in the United States may contain no added sulfites at all, while wine certified organic in the European Union may, at reduced maximums.
So the same word on two bottles means two different things about the same substance, and a bottle from one place is not comparable with a bottle from the other.
The short version
All wine contains sulfites. Sensitivity is real, uncommon, and respiratory. The headache attribution is not supported, the actual cause is unsettled, and the largest uncontrolled variables are how much and how fast.
The tannin explanation
Red wine contains far more phenolic material than white, and people who report headaches from red and not from white sometimes conclude that the phenolics are responsible.
It is a reasonable inference from a real pattern and it is not established. Red wine also differs from white in alcohol, in serving temperature, in the occasions it is drunk on and in the quantity, and none of those has been controlled in the reports that produce the pattern.
Why the belief is so durable
Because the label says contains sulfites and nothing else in the glass is named. Given a single printed ingredient and an unpleasant experience, attributing one to the other is what anybody would do.
The declaration exists to protect the small number of people with a genuine sensitivity, and it has had the side effect of nominating a culprit for everybody else.
The variable nobody controls
A tasting floor pours small measures and people visit many tables. The total is easy to lose track of and is usually larger than the same evening at a restaurant.
Anybody investigating what makes them feel unwell should start by knowing how much they actually drank, which at a festival almost nobody does. Water between tables and something substantial beforehand are the two interventions with the best evidence behind them.
What a producer can tell you
Roughly how much was added, and why, and whether the wine is one of the styles that needs more. Most will answer, and the answer is usually lower than people expect for a dry red.
The word on a natural wine label
Natural is not a defined term anywhere, unlike organic, so a bottle carrying it is making a claim nobody is checking. Some such wines carry very little added sulfite and some carry a normal amount.
If the question matters to you, the phrase to look for is no added sulfites, which is a specific claim, rather than a word that is not.
Also in this part
- 1.1
Why a dry red and a sweet chocolate fight
The wine must be at least as sweet as the food. Everything else in this entry is a qualification of that sentence.
Read it → - 1.2
Tannin and fat: what happens in the mouth
Astringency is not a flavour. You are noticing the absence of lubrication that was there a moment ago.
Read it →
For further context, see TTB sulfite-label guidance.