/ Food & Drink

Complaints help solve ‘pine mouth’ mystery

Pine nuts

There’s been a mystery afoot with pine nuts. A bitter aftertaste has affected so many that it’s earned the name ‘pine mouth’. Supermarkets didn’t believe us, but with your help we’ve got to the bottom of it.

Complaining is a big part of British culture. Sometimes we even have a good reason to go with it.

So it was slightly surprising when we looked into ‘pine mouth’ earlier this year to hear that so little was being done about an issue that was affecting so many people.

Bitter aftertaste due to unscrupulous producers

Pine mouth is a bitter, metallic aftertaste caused by the consumption of pine nuts, and can in some cases lead to nausea and stomach problems.

We first heard about pine mouth through one of our members, but after our story in August’s Which? Magazine we received literally hundreds of letters and e-mails about this problem.

But when we started researching the causes we found a lot of speculation and little in the way of facts. It took correspondence with the European Commission (EC) to get to the bottom of the problem – namely that an inedible type of pine nut from China had entered the food chain following a pine nut shortages.

Following intervention by the Chinese Chamber of Commerce, the Chinese authorities have endeavoured to stop this practice, but the EC couldn’t guarantee that there wouldn’t be further incidences.

Your pine mouth stories can help

Some issues are too big to be ignored, but while wholly unpleasant, pine mouth is thankfully not life-threatening. It does provide a cautionary tale though. When we spoke to supermarkets stocking the offending pine nuts and also the Food Standards Agency (FSA), we were repeatedly told that they’d only had a few complaints, and hadn’t deemed the issue serious enough.

Any issue relating to food safety should be brought to the attention of the FSA, local Trading Standards officers, and ourselves. This can take the form of a letter or a phone call, but don’t underestimate the power of the nag.

So with your help we can get something done. If you’ve fallen foul of pine mouth don’t just tell us about it below, email toxicology@foodstandards.gsi.gov.uk with details of the pine nuts and the length of time you suffered the bitter taste to get your case recorded.


Hello everyone, we’ve now published a new Conversation on ‘pine mouth’. The problem’s clearly lingering on and so we’ve contacted the FSA and the supermarkets to find out what’s being done to stop the sale of inedible pine nuts: https://conversation.which.co.uk/consumer-rights/pine-mouth-nuts-bitter-metallic-taste/

Eileen Baker says:
12 April 2011

I always ate pinenuts and for no reason haven’t eaten them for over three years. In this time I was treated for bowel cancer and had chemotheropy. Last week I bought some pinenuts (origin China ) sprinkled them over my salad, which I have to say were delicious (my husband had them also) but within twenty four hours a bitter taste arrived and has been with me for four days so far, not so my husband. I wondered if the effects of the chemo on my mouth ( and there were a lot ) has perhaps caused this in my case, as I did eat them a lot before with no problems, but I wouldnt have know the origins of those.

Nixer says:
13 April 2011

Well the bitter taste finally went 5 days after I had last eaten the inedible nuts. I had no reply from Holland & Barrett after the initial acknowledgement over a week ago so I chased, and still no reply. I hadn’t planned on ever shopping there again anyway but I shall be sure to tell everyone I know how little they care for their customers’ health. It would be good if someone with a bit more media power than me could go after some of these shops – there’s only so much I can do on twitter.

Janet says:
13 April 2011

I thought fellow sufferers might like to read the reply I had from Pizza Express after I emailed them to ask where they source their pine nuts from.

Thank you for your enquiry into PizzaExpress. I would like to reassure you that PizzaExpress is very aware of the ‘pine mouth’ phenomenon and are fully committed to working with our suppliers in
any developments regarding the causes of taste disturbances and will follow any worldwide recommendations, codes or practices issued as a result of continued research into the potential cause of this.

At present because it has been hypothesized that the bitter taste is due to imported pinenuts from China, which started from what was thought to be inedible species of pine nuts entering the food chain, we are currently sourcing our loose pinenuts and those used in our pesto from Korea, where
they are packed in the UK.

Our Pollo Pesto retail pizza contains a pesto which is free from pinenuts and the pinenuts going into the Pesto Genovese are from Italy.

I hope you find this information useful, but please do not hesitate to contact us again should you have any further enquiries.

Kind Regards
Natalie Rowe
Food Technical Manager

Peter says:
14 April 2011

I to have eaten pine nuts from china I bought from a village shop nr Winchester I went back to tell shop owner, and of course he wasn not the least bit interested probabaly thought I was some mad man any way what I would like to know is the medical facts regarding this taste, how do you keep getting this taste in your mouth when you eat food does it affect your liver, gallbladder, and bile if so does it cause any damage as I can say I have never expereinced any thing like this with any food I have ever eaten in my life or drink that I have drunk will some one please explain why it affects some people and not others

Craig Rushforth says:
15 April 2011

I am afraid the answer to your questions it pretty much that nobody really knows!

As a dentist I have a professional interest in pine nut syndrome – and having suffered myself I have a personal interest!

From what I have been able to determine from my internet research no-one really has an explanation for the mechanism of action, but the culprit is probably a Chinese variety of pine nut “Pinus Armandii”, which is apparently not approved as a food variety but is found in some Chinese sourced pine nuts, possibly due to a shortage of other varieties.

Apparently no-one has been able to detect any chemical difference between pine nuts which cause the syndrome and those that do not – but clearly there must be a difference at some level. Whether there is any effect on any other organs of the body is also unknown, but given that the bad taste is generally only for a week or so, and there seem to be no longer term effects, it is likely that any other effect is transitory and not serious.

It also seems that people do react differently – there are many reports of partners who have shared the same meal which has resulted in one suffering, but the other not. My suspicion is that there may be a genetic component to this, similar to the PTC phenomenon. Quotes from Wikipedia:

“Phenylthiocarbamide… has the unusual property that it either tastes very bitter or is virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is a dominant genetic trait, and the test to determine PTC sensitivity is one of the most commonly used genetic tests on humans”

or even the different way in which people perceive the taste of Swede – or rutabaga as they call it in North America:

“Along with watercress, mustard greens, turnip, broccoli and horseradish, the perceived bitterness in rutabaga is governed by a gene affecting the TAS2R bitter receptor, which detects the glucosinolates in rutabaga. Sensitive individuals with the genotype PAV/PAV found rutabaga twice as bitter as insensitive subjects (AVI/AVI). For the mixed type (PAV/AVI), the difference was not significant for rutabaga. As a result, sensitive individuals may find rutabaga so bitter as to be inedible.”

Obviously these are differences in perceptions of taste, and are not quite analogous to the pine mouth effect, but I think that genetic variation may well explain why some suffer whilst others don’t.

There’s a recent paper in the Journal of Toxicology


In the UK the Food Standards Agency clearly has know about it for some time


And there’s quite an extensive blog about the problem at


Hope that gives you some ideas to start learning about the problem!


C J Rushforth BChD

Nixer says:
20 April 2011

Holland and Barrett have finally (some 2 weeks later) replied, here’s an extract:

“It is therefore disappointing to learn of the aftertaste which you have been experiencing. We are aware that Pine Nuts can affect some individuals and I can advise that the FSA (Food Standards Authority) is aware of this issue and currently investigating the cause of this phenomenon. At the time of writing there is no conclusive explanation for this and ‘Pine Nut Syndrome’ seems to affect individual people but does not seem to be linked to a quality issue with the actual nuts.”

That’s not actually what the FSA said to me, they said “…At present it is thought that this phenomenon might be due to the pine nuts exported from China becoming mixed with non-edible species of pine nut.”

Which is a quality control issue.

H&B failed to answer my questions about whether they get their nuts from China and whether they use an FSA approved supplier. They did say something about adhering to manufacturing practices but I was unaware that the nuts were manufactured.

They offered an unspecified amount in vouchers (intended to reimburse for the pine nuts so it won’t be much) that I have to ring an 0844 number to claim! They really have no idea about customer service. I have replied and asked for (non voucher) compensation and emphasised that I had stomach cramps for 4 days but I know I won’t get anywhere with them, since I am now an ex customer there’s no incentive to placate me.

I will leave this thread to the pine nut mouth discussion now.

han says:
19 June 2011

Ive been adding nuts to my breakfast cereal recently, and about a day later i kept getting a horrible taste in my mouth which i couldnt work out what it could be. after about 2 days of this i looked it up on google and came across pine mouth. it suddenly clicked that i had been eating pine nuts!! that was the problem. i searched and searched on how to get rid of the taste as i go on holiday tomorrow and want to be able to enjoy the food without the horrible taste. There seems to be no definate solutions. i did come across a site which explained that something from the pine nuts affects your taste buds. still searching and searching for a cure, my boyfriend had made me a sausage cob, i added a lot of brown sauce in the hope this would cleanse my tongue (everyone knows what brown sauce can do to a dirty coin so i thought the same would apply lol) whilst eating the cob my taste seemed to return. i thought i would wait until this morning to see if it was still the same, the sour taste seems to have faded A LOT. So for lunch im gonna have another cob with a dose of brown sauce 🙂 and hopefully i will be back to normal.