Consumer Alert: Worried about mercury in your tuna? A new CR study says you should be.

ROCHESTER, N.Y. If you love your tuna, you need to keep reading.

A new study by Consumer Reports is a reminder that “all things in moderation” is a good rule to live by. Consumer Reports says that adults should eat some of the most popular types of tuna no more than once a week. And in most brands of albacore tuna, the levels of mercury are so high, Consumer Reports says healthy adults should only have one serving a week, and children shouldn’t eat it at all.

First, let’s talk about the extraordinary benefits of tuna. It’s rich in vitamin B-12 and omega-3 fatty acids and it lowers bad cholesterol. Doctors say it helps keep your eyes healthy, prevents cancer and supports weight loss.

 But anything that swims in the ocean likely has some level of mercury. That’s because the mercury that’s released from coal-fired plants ends up in the water and when combined with bacteria, it becomes methylmercury, a toxin that affects your nervous system. And tuna have more methylmercury than some other seafood we eat because tuna feed on other fish.

 Albacore tuna has far more mercury than chunk light tuna. Light tuna is made up of a mix of small fish like skipjack tuna with short life spans. Albacore tuna are big fish with huge appetites. They’re predators, feeding on smaller fish, so many of them that they eat as much as 25 percent of their body weight every day. And they live up to 12 years, all the while the mercury from all those fish they eat daily accumulates in their bodies, and is then eaten by you and me.

 Consumer Reports tested these six brands, Bumblebee, Chicken of the Sea, Safe Catch, StarKist and Wild Planet. It then determined how many servings are safe for an adult to eat per week. An adult serving is one five-ounce can. In all the brands but Bumblebee, you can have only one serving per week of albacore tuna. Bumblebee’s mercury levels were low enough on average that an adult could have two servings.

CR’s tests found that with the exception of Wild Planet, adults can safely eat three servings per week of light tuna. But the levels were so high in Wild Planet tuna, Consumer Reports recommends no more than one serving per week.

As for children, Consumer Reports recommends only light tuna. They should have two, one to four-ounce servings depending on their age. Keep in mind these recommendations are based on the assumption that tuna is the only fish you’re eating that week.

And this is important. Consumer Reports says if you’re pregnant, you shouldn’t eat any tuna at all because testers saw random spikes in high levels of mercury in cans of all brands. Therefore, they determined it’s not worth the risk to the development of your baby’s brain.