Pine mouth puzzle: Why do these nuts leave you with a bitter taste?



They are a favourite with celebrity chefs and hailed as the latest healthy salad ingredient.



But a liberal sprinkling of pine nuts over your dinner could also leave a bitter taste in your mouth.

Increasing numbers of people have reported that after eating pine nuts, typically as a snack or in a pesto sauce, they have developed a foul, metallic taste in their mouth lasting for up to two weeks, making practically all food and drink unpalatable.



Pine nuts have been causing 'pine mouth' - a long-lasting bitter taste in the mouth

The first reports of 'pine mouth', as it has been dubbed, began last winter in the U.S. from those who had eaten imported Chinese pine nuts.

Now pine mouth has spread to Britain, and shoppers across the country are experiencing the same disturbing symptoms.

I, too, fell foul of the metal mouth syndrome after eating a few handfuls of pine nuts bought from a supermarket.

Though I regained my taste after eight days, the only thing I could drink during that time was water, and the only food that was bearable was salad leaves smothered in strong balsamic vinegar. Drinking wine was like swallowing liquid metal.

Most worryingly of all, neither I nor my GP had the slightest idea what was wrong with me.

Until, that is, I typed the words 'bitter taste' into my internet search engine, and came across several hundred web postings from pine mouth sufferers all over the world.

When approached, they are only too happy to tell their story.



'The bad taste in my mouth lasted for a fortnight, and for the first ten days it didn't improve at all,' says Danielle van Duin, from Holland.

'I was conscious of it all the time - I thought I was going to be condemned to have it for ever.'

Kristin Donnelly, editor of online magazine Food & Wine, had the same problem. 'No matter what I tasted, there was a medicinal flavour at the back of my throat,' she says.



So perturbed by his symptoms was Roger Hyam, a botanist from Edinburgh, he thought he had jaundice or diabetes.

He has since started a pine mouth website in the hope fellow botanists might be able to offer help or an explanation.

Those who found out about pine mouth via the internet were the lucky ones.



Others sought medical help and were sent for blood tests or liver scans, while some approached their dentist to see if mercury was leaking from their fillings.



Home remedies recommended by sufferers include drinking liquid aloe vera and taking activated charcoal tablets (charcoal is often used as a detox in cases of drug overdose).

So what's actually happening here? And should we be worried?

In reply to a group of pine mouth sufferers in Wales, the Food Standards Agency contacted doctors at the Brussels Poisons Centre, who have carried out tests on the pine nuts, but have been unable to identify any chemical differences between those that cause pine mouth and those that don't.

The good news is that no pesticide or heavy metal contamination has been found in the pine nuts. The puzzling news is that while some people get pine mouth, others don't, even though they've eaten the same batch of nuts.

'It doesn't seem to be an allergic reaction, either,' says John Collard, clinical director of charity Allergy UK.



'It may be there is a chemical constituent in the nuts that causes the taste; possibly the oils in the nuts have gone rancid because of poor storage.

'Just as caffeine increases some people's heart rate more than others, some people may be susceptible to these oils, and some not.'

But in the meantime, food retailers are not rushing to warn the public, despite shoppers at most of the major supermarkets claiming to have experienced the problem.

While Tesco says it will look into the matter and Asda is not aware of any complaints, it's a different matter for Sainsbury's customers.



Clearly displayed on its customer web-forum are seven pages of postings from pine mouth-afflicted shoppers.

'This appears to be a rare occurrence associated with a small quantity of pine nuts sold in Britain as well as in other countries,' said a Sainsbury's spokesman.

'They do not represent any health concerns, but we're happy to exchange the product should customers want to return them.'



