Media outlets and activist groups seem to love regurgitating the myth that eating store-bought tuna can cause mercury poisoning. And every so often, a new celebrity will come out with a claim that fish made him or her gravely ill. The latest is Tiffani Thiessen (remember her?), formerly of Saved by the Bell and Beverly Hills, 90210. From an interview with Parent Dish:

PD: I read that you didn't have the easiest road in terms of getting pregnant?
TT:
I had mercury poisoning so we decided to wait until I was mercury free to try and get pregnant. I had to go through a whole process, which took over a year to get rid of all of the mercury that was in my body.

PD: How did you get mercury poisoning?
TT:
I was a non-meat eater for 15 years. I would only eat fish and ate tuna twice a week, which I did not think was a big deal. Apparently, it was. Tuna is high in mercury and did not do well in my body.

The idea that Thiessen contracted mercury poisoning from eating tuna twice a week is preposterous. Thiessen is 5-foot-5, so let’s estimate that her weight is about 130 pounds. By government standards, a 130-pound person would have to eat more than 24 cans of light tuna per week (over her entire lifetime!) to have a new health risk from ingesting too much mercury.

And even if she were a raging pescetarian, it’s still highly unlikely that she’d get sick. The medical literature doesn’t contain a single documented case of mercury poisoning in the United States caused by eating commercially bought fish.

In fact, as a new mom, Thiessen’s penchant for fish was probably healthy for her and her baby. Oily fish, in particular, is rich in omega-3, an essential fatty acid. One study found that babies born to mothers who consumed lots of omega-3 had attention spans two months advanced of those born to moms with lower omega-3 levels. Other research suggests that children born to mothers with low omega-3 levels are at greater risk of having low IQs.

Scientists also caution that the hype about hypothetical mercury risks could actually do more harm than good. Harvard’s Dr. Dariush Mozzafarian notes, “[T]he dangers of not eating fish [including tuna] outweigh the small possible dangers from mercury … The real danger in this country, the real concern, is that we're not eating enough fish.” And National Institutes of Health physician Joseph Hibbeln notes that the mercury scaremongering is particularly affecting pregnant women: “We found consistently that when women ate more than they were supposed to, more than advised, their children had higher IQs at age 8, their children had better social skills and peer development at age 8.”

Thiessen isn’t the first celebrity to make hay out of this supposed ailment. Two years ago Entourage star Jeremy Piven dropped out of a Broadway show, claiming he had mercury poisoning after “20 years of eating only fish,” particularly sushi. We threw cold seawater on Piven’s dramatics, calculating that he would need to consume 108 pieces of tuna sushi roll every week for his entire life to contract food poisoning.

Piven’s health problems were apparently short-lived. Last year he was spotted at a Chicago restaurant enjoying a delicious meal of whitefish. How soon will it be before we see Thiessen noshing on a tuna salad sandwich?