A slightly shorter version of this article is published by the Financial Times. See the allergies and intolerances entry in your online Oxford Companion to Wine for an outline of the difference between the two.
Have you ever wondered about the message ‘contains sulphites’ on almost every bottle of wine? And have you ever wondered why some people find even a moderate amount of wine disagrees with them? Contrary to popular belief, the two may not be related according to new research by Master of Wine Sophie Parker-Thomson, who was once a lawyer but is now a wine producer and consultant in Marlborough, New Zealand.
After passing gruelling written exams and three sessions involving blind tasting, each prospective MW has to submit a research paper in order to be awarded the hard-won letters after their name. Many of the topics chosen are, frankly, of distinctly limited interest. Recent topics have included ‘Online wine tasting courses in Norway. Examining the quality of corrective feedback through an online platform and the opportunities for development’ and ‘A scientific study comparing the influence of three different strains of Oenococcus oeni on malolactic fermentation kinetics and chemical properties relating to the colour and flavour of Pinot Noir wine from Burgundy’.
But Parker-Thomson’s research, described here by Julia and defended here by its author, into ‘the relationship between the use of sulphur dioxide and biogenic amine levels in wine’ may have seriously wide-ranging effects on how wine is made and provide useful guidance for winemakers and clues for people who feel terrible after drinking wine. (We’re not talking hangovers here, but nasty effects caused by something other than alcohol.) I for one am delighted by Parker-Thomson’s work as I have long been frustrated by the wine industry’s apparent insouciance towards the problem of wine intolerance, which apparently affects between seven and eight per cent of the population. The tide may be turning however. When last July the Institute of Masters of Wine held a webinar based on her findings, no fewer than 500 people from 50 different countries signed up for it.
Despite being the fifth most common element on earth, sulphur, or sulfur, or even brimstone, has a bad rap – as witness the connotations of the adjective sulphurous. It’s unfortunate that it plays a part in sulphites (sulfites in the US), the inclusive term for several preservative compounds including sulphur dioxide (SO2), which can be an invaluable tool in winemaking and food processing. It’s supremely good at inhibiting harmful bacteria and preventing fresh food and drink from turning brown.
It is true that in the late 1970s and early 1980s it was common practice to blanket salad bars and fruit and vegetable counters with sulphites so excessively that several serious reactions in some asthmatics were caused. The result was that in 1988 the US Food and Drug Administration insisted that labels on all food and drink with more than 10 parts per million (ppm) should specify ‘contains sulphites’ and this has been adopted globally, with sulphites sometimes being coyly denoted by E numbers beginning E22.
Since then producers of many other comestibles such as fruit juices and dried fruits, which used to contain far higher levels of sulphites than most wines (dried apricots, for instance, may contain hundreds, even thousands, of parts per million), seem to have sought alternative preservation methods that avoid the sulphite declaration. So wine remains the one product most obviously related to sulphites. And in an age when any additive is seen as wicked, sulphites have been so demonised that a growing category of ‘no added sulphites’ (and sometimes, with less scientific rigour, ‘no added sulphur’) wines has emerged.
The fact is that all wine naturally contains traces of sulphites, and anyway sulphite use by winemakers has fallen dramatically over the last few decades to rarely more than 150 ppm in dry wines. However, as Parker-Thomson’s research demonstrated, their absence in wine can ironically pose greater health risks than their presence.
Although sulphites are routinely blamed for adverse reactions to wine, studies show that sulphite sensitivity is confined to a small proportion, three to ten per cent, of people with asthma, generally those affected seriously enough to be on daily steroids. Reactions to sulphites are strictly respiratory rather than the litany of ill effects caused by wine intolerance in the general population. And if sulphites were to blame, you would expect more complaints about white wines, which tend to have a higher level of sulphites than reds, whereas the reverse is the case.
Parker-Thomson’s research suggests that it is not sulphites to blame for wine intolerance but a group of compounds called biogenic amines, of which the most common, and the most toxic to humans, is histamine. (Two of the others that may cause problems, along with tyramine, are the delightfully named putrescine and cadaverine.) The symptoms of biogenic-amine toxicity, such as headaches, nausea, rashes and flushes, exactly mirror those associated with wine intolerance.
Biogenic amines are produced by certain bacteria which happen to be acutely sensitive to SO2. So the recent trend towards deliberately making wine with very little of the antimicrobial SO2 creates the perfect environment for bacteria that produce biogenic amines to flourish.
Our individual sensitivity to biogenic amines varies according to our genetic make-up and the state of our gut. Alcohol also plays a part, in that it stops the specific enzymes that allow our bodies to get rid of excess biogenic amines, so biogenic amines are particularly harmful in alcoholic drinks such as wine. Apparently, taking antihistamines won’t necessarily help because some of them stop those enzymes from working properly, and some also interfere with our ability to process alcohol. And if wine is combined with a food rich in biogenic amines such as mould-ripened cheese, then the effects can be truly miserable for those who are sensitive to them.
Parker-Thomson’s research included testing the effect of different winemaking techniques on the level of biogenic amines in 100 different New Zealand Sauvignon Blancs. (She chose whites because what little research has been done in this field has been on reds, and she deliberately included some no-sulphite wines, a group that had not been included in any related research before.)
The key finding was that so long as a small amount, as little as 30 mg/l (or 30 ppm), of sulphur dioxide was added before alcoholic fermentation, the biogenic amine level in the resultant wine was inconsequential and the different winemaking techniques had little bearing on final concentrations. However, biogenic amine levels were highest, at levels certain to cause reactions in sensitive individuals, in wines either with no sulphites added at all or with sulphites added only late in the winemaking process.
The natural-wine movement, with its distaste for added sulphites, seems to have caused a significant increase in the incidence of biogenic amines, as has climate change, which has lowered levels of the acidity naturally present in grapes and which can protect against harmful bacteria.
Parker-Thomson’s research seems likely to provoke considerable revision in winemaking practices and in how sulphites are perceived in a wine context. This is not to denigrate natural wines, simply to highlight one way in which they may not be healthier than more conventional wines as has previously been supposed.
There is no doubt that if you are very severely asthmatic, then it would be best to steer clear of any food or drink containing sulphites in order to avoid serious respiratory problems. But for those who find wine gives them a headache, makes them itch, feel sick, or suffer swollen or burning lips, it is probably not sulphites that are the cause. In fact, if used appropriately, sulphites could provide the winemaking solution.
Dr Patrick Lucas is a professor of microbiology in Bordeaux and has closely studied biogenic amines. He reported during the webinar that the Paris-based umbrella wine organisation the OIV, or Organisation Internationale de la Vigne et du Vin, is actively against regulations limiting biogenic amine levels in wine (Switzerland once imposed maximum histamine levels in wine), but is already actively spreading information to wine producers on how to produce wines that are low in them.
Perhaps sulphur is not so sulphurous after all.
Wines likely to be low in biogenic amines
Fresh, fruity white wines that are released soon after bottling and that have ‘contains sulphites’ on the label, such as young, unoaked Sauvignon Blanc, Riesling or Pinot Grigio.
Wines that may have relatively high levels of biogenic amines
Those that have spent a very extended time on lees, such as mature traditional-method sparkling wines, champagne for instance, which tend to have low SO2 additions for quality reasons.
Tips to avoid biogenic amine toxicity
Drink lots of water – natural histamine levels increase with dehydration.
Try to avoid or limit intake of foods high in biogenic amines when drinking alcoholic drinks. These include bacterially ripened cheeses such as Gorgonzola or Epoisses; cured and fermented meats such as salami; aubergine; sauerkraut and other fermented vegetables; fermented soy products; aged fish products.
If you are particularly affected by wine intolerance, you should probably avoid wines that have no or low SO2.