Mercury tests not needed unless signs of exposure become apparent

Smart seafood choices can help keep ingestion of element at safe levels

Dear Doctor: I’m a healthy, 54-year-old female who recently found out from a blood test that my mercury level is 17. I do not eat meat, but I do eat quite a bit of seafood, including sushi. I got tested because I eat a lot of seafood and know that mercury can be an issue.

I do not have any symptoms, as far as I can tell.

Is 17 way-too-high a level for a healthy adult?

How concerned do I need to be?

I’ve read that “toxic levels” are far higher than 17 (I understand that you do not want to see elevated levels for a growing child or pregnant woman).

Should I stop taking cod liver oil? Are the benefits of cod liver oil greater than the potential tiny amount of mercury it adds? Is it possible to get fish oil prescribed by physicians that might be healthier?

Would you recommend some kind of treatment plan in my case, with retesting?

My physician has not offered any suggestions at this point. — F.L.

A: There are three forms of mercury: metallic mercury, such as in a thermometer, which is toxic if inhaled; inorganic mercury, which is toxic, especially to the kidneys, and is found mostly through industrial exposures; and organic mercury — for most people, the major source is fish, especially tuna, shark, swordfish, king mackerel and tilefish.

Most people in North America have small amounts of organic mercury in their blood, but symptoms become more likely when mercury levels are above 50, and levels above 100 are likely to have symptoms such as tingling sensations around the mouth or in fingers and toes, and poor muscle coordination.

In someone with no symptoms, mercury testing generally is not recommended. In that case, no treatment is necessary for a level like yours.

I do agree that you should avoid fish that are at high risk for mercury, and instead eat low-risk fish like shrimp, salmon, canned light tuna and catfish.

Fish oils do not contain much mercury, as the mercury is bound to the proteins in the fish and does not go into the fat used to make medicinal fish oil.

Still, I don’t recommend cod liver oil, as it isn’t generally needed for healthy adults with a good diet.

Dear Doctor: My father had a stroke last year. This year he had a ministroke.

Can an oxygen tank prevent this? He has not changed his diet or exercise. What steps can he take to prevent another stroke? —K.

A: A stroke is death of brain cells. The most common causes are blood clots in the brain and bleeding, but all strokes are due to lack of oxygen to the brain.

It seems reasonable that adding extra oxygen might help; however, oxygen is only useful for people with severe lung disease and low oxygen levels.

People with normal oxygen levels can completely oxygenate blood.

The problem in a stroke is that the oxygenated blood can’t get to that part of the brain due to blockage or bleeding inside the brain.

While treatment depends on the specific type of stroke he had, all people with a history of stroke benefit from careful observation of blood pressure, blood sugar if appropriate and abstinence from tobacco.

A plant-based diet with little refined sugar probably is helpful, as is regular exercise if approved by his physician, who also may prescribe medication if appropriate.

Readers may email questions to ToYourGoodHealth@med.cornell.edu