Mercury in fish poses heart risk for middle-aged men, study says
Jane Kay, Chronicle Environment Writer
Tuesday, February 8, 2005
Eating fish high in mercury puts middle-aged men at a greater risk for coronary heart disease and may offset the protective effects of omega-3 fatty acids in some seafood, according to an important new Finnish study.
The study is significant because it could trigger new advisories that protect the general population from mercury in seafood. At present, government warnings focus on protecting fetuses and children from neurological damage.
The findings, published in a recent issue of an American Heart Association journal, show that men with the highest levels of mercury in their hair had a 60 percent increased risk of an acute coronary event and a nearly 70 percent increased risk of cardiovascular death compared with men with lower mercury levels.
Men with the highest levels of mercury in their hair, which is a standard method of measuring mercury in the body, consumed more than two times the amount of fish as those with the lowest levels.
The findings were based on an ongoing 14-year study by the Research Institute of Public Health at the University of Kuopio of 1,871 men ages 42 to 60 and free of previous heart disease or stroke.
Mercury, highly toxic to the neurological system, is released into the environment from power plants, factories using chlorine, mining and rock formations. The metal ends up in oceans and lakes, where long-lived fish consume it.
Fetuses and children are particularly vulnerable. But physicians report memory loss, headaches, abdominal pain, behavioral problems, fatigue, hair loss and arteriosclerosis among adults.
The U.S. Food and Drug Administration warns pregnant and nursing women --
and all women of childbearing age -- not to eat swordfish, shark, king mackerel and tile fish. The FDA cautions that albacore tuna has three times the mercury of chunk light tuna.
In addition, the U.S. Environmental Protection Agency has established a mercury guideline to protect the most sensitive populations. And the American Medical Association has advised that mercury can harm the heart.
In the new study, researchers found that high mercury concentrations in the body reduced the heart-protective effects of the fatty acids in fish oils.
They hypothesized that mercury promotes free radicals in the body, which can harm cell membranes and tissues, and at the same time reduce the body's ability to protect against the formation of the free radicals, increasing the vulnerability to heart attack and death.
San Francisco physician Dr. Jane Hightower -- who found a correlation between high mercury levels in her patients and the consumption of swordfish, ahi tuna, Chilean sea bass and other fish -- on Monday called the study an important research contribution.
"There appears to be a threshold at which the risk of mercury outweighs the benefit of omega-3 fatty acids in regard to cardiovascular disease,'' said Hightower. The literature indicates the threshold is near the guideline set by the EPA, and would correspond to a hair level of 1 microgram per gram, she said.
In the Finnish study, the average mercury content of hair was 1.9 micrograms per gram with a high of 15.7 micrograms per gram.
Hightower's Bay Area patients had even higher levels. The average mercury content of hair was 3.5 micrograms per gram. A patient who ate lots of swordfish had a level of 22 micrograms per gram.
"Our high-end consumers who eat swordfish and ahi tuna are just as high as the populations being seen around the globe for mercury problems -- in the Faro Islands, the Seychelles and among the Inuits,'' said Hightower.
She found atherosclerosis in many of her patients, including coronary artery disease, heart attacks, peripheral vascular disease and stroke, but she said she wouldn't be able to prove that mercury had caused their disease.
Hightower has written to the FDA advising that if the scientific literature continues to find a link between mercury and atherosclerosis, it should expand its advisories to protect the general public..
A mercury calculator compares fish consumption to the EPA guidelines at www.gotmercury.org
E-mail Jane Kay at jkay@sfchronicle.com.
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/02/08/MNGL8B7E921.DTL
|
IP Address : 59.10.255.115
|
