Mercury is a dangerous heavy metal that can damage the brain
and kidneys if ingested. Women who are or may become pregnant
are especially encouraged to avoid eating foods that may contain
mercury, namely larger fishes. Recent evidence in The New
England Journal of Medicine suggests that people in general
should avoid some fishes high in mercury, because they may
also increase the risk for cardiovascular disease, thus eliminating
the protective effects of the omega-3 fatty acids found in
A study conducted in eight European nations and Israel was
designed to find out how mercury levels in the body affect
risk for cardiovascular disease and to see if high mercury
levels can eliminate the heart-protective effect of eating
fish. Researchers measured toenail mercury levels in approximately
700 men who had suffered a heart attack, and another 700 who
had not. They also measured levels of the healthy omega-3
acid DHA, provided by fish and fish oil, in these men.
Mercury levels in men who had suffered heart attacks were
15% higher than in men who had not; the odds for a heart attack
were twice as high in men with the highest mercury levels
as in men with the lowest levels. Conversely, higher DHA levels
were linked to a reduced risk for a heart attack, as previous
studies have shown.
the question regarding fish consumption is, to eat or not
to eat? If you are eating fishes high in mercury, you are
probably negating the positive effects that could otherwise
be obtained from them. Fish to be avoided, in order of higher
to lower mercury levels, include tilefish, swordfish, mackerel
and shark. Most smaller fishes and shellfish have low mercury
concentrations, and are safe to eat.
Guallar E, Sanz-Gallardo MI, et al. Mercury, fish oils, and
the risk of myocardial infarction. The New England Journal
of Medicine 2002:347(22), pp. 1747-1754.
Additional information on the benefits of proper nutrition
can be found at https://www.chiroweb.com/tyh/nutrients.html.