Tolerance v intolerance

15 June 2021 Sophie adds I have subsequently discussed my research with Markus Herderich, Eric Wilkes and Mark Krstic from the Australian Wine Research Institute. We agree that reducing microbiological problems associated with the production of biogenic amines in wine warrants further investigation and collective action needs to be taken to better disseminate the relative safety of SO₂ and its usefulness within the wine industry.  Accordingly we look forward to working collectively to develop information resources and guidelines for winemakers to adopt best-practice SO₂ use and to guide future research in this area.

10 June 2021 We're republishing this article free as we feel this is a topic of considerable potential importance, as do several scientists at the Australian Wine Research Institute.

7 June 2021 Sophie Parker-Thomson MW presents a robust defence of her Master of Wine research into why some people react badly to wine.

Over the past few months since my Master of Wine research paper on the relationship between sulphur dioxide and the levels of biogenic amines in wine was published (summarised in this article), I’ve had many people contact me. The responses have been overwhelmingly positive, with winemakers and wine professionals, particularly those with biochemistry backgrounds, exclaiming that the findings are like a eureka moment in the understanding of biogenic amine (BA) production and accumulation in wine. I’ve also had numerous wine drinkers thank me for going a fair way towards identifying the reasons they can or can’t drink particular wines for fear of suffering adverse reactions that are not attributable to overindulgence in alcohol itself.

My paper conducted a substantial literature review on wine intolerance and established that the most likely cause of this surprisingly common condition is BAs. Ingesting these bacterially created chemical compounds in an amount higher than our bodies can naturally detoxify, triggers responses that match the complaints we hear from those who suffer from wine intolerance. The symptoms are wide ranging and include, among others, headaches, migraines, rashes, heart palpitations, flushing, stomach upsets, hyper- and hypotension and nasal congestion. What makes BAs more significant in wine is that alcohol inhibits the enzymatic detoxification of them.

The research established that a winemaker making a small addition of sulphur dioxide (SO₂ or sulphites) to the grape juice before alcoholic fermentation begins (as little as 30 ppm) is enough to make the environment hostile to the bacteria that can produce BAs. This single step then affords the winemaker stylistic freedom to employ techniques which have traditionally been identified as increasing BAs such as malolactic fermentation, spontaneous fermentation, skin contact and lees ageing. In my research it became clear that wines with no added SO₂ or only late-added SO₂ were likely to have the highest levels of BAs, and the winemaking practices that traditionally increase BAs only compounded the resulting levels in the wine.

There is irony in this finding as there is a widely held misconception that sulphites are the main source of wine intolerance in consumers. Clinical studies demonstrate, however, that sulphites are a health risk to only 3–10% of diagnosed acute asthmatics, and that reaction is nearly exclusively a respiratory one. These individuals must avoid all foods, drinks and other products that contain sulphites, or risk severe consequences such as anaphylaxis – hence the requirement for mandatory sulphite declarations on product labels.

In my paper I concluded by stating that the findings herald an exciting time for the industry: performing a very simple step in the vinification process goes a long way towards ensuring that the resulting wines are very unlikely to give the consumer the types of reactions that drive them away from drinking wine altogether. As much as 10% of the general population are estimated to have a wine intolerance issue. If wine producers are able to slightly alter (or indeed maintain) their winemaking practices, and if the wine industry allows the identification of low-BA wines, this would be a very positive step towards re-engaging a portion of would-be wine consumers.

Most importantly, however, I highlighted that this is an area that needs further research, and called for more robust clinical trials to investigate real-life dose-responses to high-BA wines to establish what the thresholds are. Just how extensive a problem BA toxicity is cannot be quantified until these trials are conducted. It is unfortunate that some individuals have been too quick to dismiss the problem, without evidence or justification, because it is perceived as an inconvenience or does not align with what they personally believe, which is precisely the opposite of good science.

A case in point is Jamie Goode’s article in the Wine Enthusiast in which he not only misquotes me, but also cherry-picks a very small section of the research in order to provoke an emotive response from the natural-wine sector, which is not what my paper is about. The article is geared toward downplaying the significance of BAs in wine, when it is apparent that this is a very real issue that affects a surprising number of people. Even the responses on Twitter to Goode’s post linking to his article demonstrate this:

‘… I find a lot of sulphite free wines give me headaches these days and I only drink a couple of small glasses.’ @PiemonteDreams

‘By coincidence I have reading up on histamines [sic] in wine recently, & wondering if they were causing my savage hangovers. For the past 2 weeks I have been taking one-a-day anti-histamine tablets, and my hangovers have genuinely reduced in severity by about 80%.’ @WillSmale1

‘As soon as I sneeze when having a drink I take an antihistamine and problem solved. Also with beer.’ @libiamowine

Goode wrote in his 2018 book Flawless: Understanding Faults in Wine, that ‘the presence of biogenic amines [in wine] is always undesirable’, suggesting they are the most likely cause of adverse effects on wine consumers causing ‘headaches, breathing difficulties, hypertension or hypotension, allergic reactions, and palpitations’. It is not apparent what has caused Goode’s departure from this position except perhaps an enthusiasm for certain wine styles.

The article is overall problematic because it dismisses the need to investigate BAs in wine when the literature, including Goode’s own book, identifies them as a very real health risk that warrants further research, especially in view of today’s trend towards using less microbial protection in winemaking.

What prompted my study in the first place was the absence of data on BA levels in the growing category of zero- and low-SO₂ wines, as well as the lack of investigation into the effect of the timing of SO₂ additions on resulting BA levels. The results of my study were conclusive, that wines with zero- and low-SO₂ regimes had the highest BA levels, and that timing of SO₂ addition was crucial. Therefore, the studies, including the Australian Wine Research Institute (AWRI) survey mentioned by Goode in his article, are not relevant as they do not include these wines, which means that the average levels reported in the AWRI survey cannot apply to these categories of wine.

Below is a table from my study showing the mean BA values in mg/l ± standard deviation across the different SO₂ regime wines. It is observable that zero-add and low-add wines do have concerningly high average BA levels, with zero-add wines having over 11 mg/l and low-add wines 6.54 mg/l of histamine respectively. It is important to note that this study analysed 100 commercially available wines, all of one white grape variety – Sauvignon Blanc – so the question must be asked, as BA levels in red wines are typically higher than in white wines, what would the results be for red wines made with zero or low SO₂ additions?

Further data in my study showed that timing of SO₂ is very important: a very small amount of SO₂ added early is enough to mitigate the risks of BA accumulation, due to the antimicrobial effects of total SO₂, whereas Goode erroneously claims that the paper states a high level of control is required. I suggest in my paper that, due to the powerful statistical significance of the results, perhaps wines with no or only late-added SO₂ should carry a mandatory high-BA warning on labels to warn sensitive consumers.

I do not advocate universal testing or labelling of BAs in wines because of the administrative and financial burden this would place on the industry and anyway such a measure would not be warranted because of the varying impact BAs have on individuals. Instead, I suggest that the best approach would be to allow producers to indicate that a wine is low-BA via a logo or similar, so that sensitive consumers who know or suspect they are sensitive to BAs can actively search for this logo in much the same way that low- or no-alcohol wines or vegan wines are identified. 

Goode recommends that individuals sensitive to BAs choose wines that have not been through malolactic fermentation (MLF) as an assurance of low BA levels. However, MLF itself does not cause BA accumulation. Rather, it is the microbially hospitable conditions created to carry out MLF that are propitious to the growth of bacteria which can result in increased BA production. You do not need MLF to have high BA levels if the bacterial growth conditions are favourable (e.g. high pH, low-/no-SO₂ environments). This is a frequent misunderstanding.

Based on the research, my own recommendation to BA-sensitive individuals is to avoid wines that have had zero SO₂ added prior to alcoholic fermentation. Sensitive consumers are advised to select fresh and fruity wines such as Riesling and Sauvignon Blanc, which, owing to their production methods, are most likely to have received an SO₂ addition early.

Weighing up the health risks, it was mooted in Goode’s article that alcohol’s toxic nature merits exclusive attention. I argue that while wine indeed has alcohol in it, BAs combined with alcohol is even more of a concern to health. Alcohol is not an optional component of wine and consumers know that, but BAs are, yet consumers are in the dark. Should we not be doing more as an industry to try to mitigate health concerns where we can? Do we not owe it to consumers to investigate and research this further, and as an industry take action? As I point out in my research, legally and morally there is an arguable case to do so.

My paper does not single out natural wine, because the natural-wine movement is not united on when and how much SO₂ should be added. I have never maintained that every natural wine will have issues with high BA levels. However, I do take issue with producers who say or infer that because they have added no SO₂, the wine will be in any way better for you. My research indicates the contrary could be true. I would like to think that producers will look at this research with an open mind. There are some very small adjustments that can be made to winemaking that will make a big difference to resulting BA levels. A winemaking protocol at the end of my paper lays this out and, frankly, the demonisation of SO₂ is not supported by the published research.

If adding a very small amount of SO₂ at the beginning of fermentation will kill the natural wine movement as Goode claims, then perhaps we need to question the rationale of the sector altogether. What is more important: profiting from a single-minded philosophy, or the health of your consumers?

A good scientist is open minded, forming an opinion based on the evidence rather than trying to find one’s opinion in the evidence. Goode’s article regrettably illustrates confirmation bias, and his commercial interest in no- and low-SO₂ wine retailing remains undisclosed in the Wine Enthusiast article. The opinions of Douglas Wregg, who makes a living from importing and selling no- and low-SO₂ wines through Les Caves de Pyrène in the UK, are solicited as evidence to dismiss this research. I was never contacted by Goode in relation to this article.

There needs to be greater transparency, sound judgement and less emotive reaction in the wine industry, particularly from our wine communicators.