'Pine Mouth': How Pine Nuts Can Ruin Tastebuds for Weeks

Jul. 7, 2010— -- It's a chef's worst nightmare: to wake up one morning to find that food has lost its flavor -- that every morsel to cross your lips tastes bitter, metallic, and inedible.

This was the fate of San Francisco-based chef and food critic Jenna VanGrowski, 30, who suffered from a bizarre taste disturbance last month known as "pine mouth."

Though she didn't know it at the time, the bitter aftertaste that came with anything she ate was due to a rare and seemingly random reaction to eating pine nuts. She snacked on some two days before.

Various "palate cleansing" foods failed to get rid of the metallic aftertaste, known medically as metallogeusia.

When even the taste of toothpaste was "almost unbearable," she says she started to worry.

"I'm a chef, so I started getting really scared and frustrated because I need to be able to taste to do what I do. I had no idea what the heck was going on."

Van Growski works for ChefsBest, an organization that judges food products.

But as she soon found, she was not alone.

A quick Google search uncovered dozens of others on blogs and Facebook reporting her same symptoms and calling it "pine mouth syndrome."

The cause? It seemed the handful of pine nuts she snacked on days prior was the unlikely culprit.

Fortunately, she also discovered that the reaction is temporary; most cases go away on their own in one to four weeks.

One of the most interesting things about pine mouth is that it's a recent phenomenon," says Dr. Marc-David Munk, an emergency physician at the University of New Mexico who wrote about his own ordeal with pine mouth as a case study in the Journal of Medical Toxicology last year.

"It has really come onto the scene in the last two years," he says.

Though it was first documented in Belgium in 2001, there has been a surge in the number of cases reported since 2009, both in the U.S. and the U.K.

Since the Food and Drug Administration began tracking this affliction in February of 2009, over 50 cases have been reported, says FDA spokesperson Ira Allen.

"We're collecting information on this where we can and we count on the public to help [by reporting cases to the FDA]," Allen says.

Pine Nut Panic

Certain medications, such as some antibiotics and anti-hypertensives, are known to cause a similar metallic taste in the mouth, but having this reaction from eating pine nuts poses a bit of a mystery, says Dr. Beverly Cowart, clinical director of the Monell-Jefferson Chemosensory Clinical Research Center.

Because it only occurs with some pine nuts and only to some people, it's difficult to say what might be causing it.

Some have suggested that because pine nut oil spoils easily, victims could be eating spoiled nuts, Munk says.

But at least in VanGrowski's case, she says the nuts were fresh and had not passed their expiration date.

"As a chef I'm well-attuned to tastes. I would know if they were rancid," she says.

Cowart says a fungus that grows on the pine nuts could also be behind the taste effects, though it is unknown as of yet whether the nuts in question had anything on them.

Another hypothesis -- one that is becoming increasingly accepted -- is that certain non-edible varieties of pine nuts are being passed off in the marketplace as the edible variety, Munk says. Some researchers have implicated China in exporting these non-edible pine nuts.

Though VanGrowski says she threw away the offending pine nuts in a fit of anger and frustration, she says that she had checked first to see where they came from. Among three possible sources listed, China was among them.

The FDA is currently testing samples of those nuts that have spurred pine mouth, though no results from these test are currently available.

It's not often that people actually lose their sense of taste, Cowart says.

More often than not, people mistake a loss of smell for a loss of taste, as much of what we interpret as "flavor" is aided by the smell of a food.

"Taste is limited to sweet, sour, salty, bitter, and savory. A lot of what people refer to as taste is actually smell," she says.

There's No Accounting for (Disturbed) Tastes

But when taste itself is affected, it often has to do with the delicate balance of oral flora that keeps our mouth in check. This is why antibiotics, which can kill the natural, helpful bacteria in our saliva, can lead some to experience temporary changes in taste. One of the five or so "tastes" the tongue senses gets thrown out of whack. If bitter reigns, food will take on a metallic, bitter flavor, despite its inherent sweetness or tangy sourness.

Though these taste problems, as with pine mouth, are fortunately short-lived in most cases, they can be very difficult to live with, Cowart says.

"Food is such an important part of people's social life. It's really disruptive to not be able to enjoy it," she says. "Fortunately, these things tend to correct themselves in time."