Something Fishy This Way Comes
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Fish oil remains one of my favorite nutritional resources – whether derived from eating fish directly, or from extracted fish oil. It is one of the few substances around with a lot of good research indicating benefits for cardiovascular health plus anti-inflammatory properties, with virtually no negative effects. As a rule I prefer whole-food sources of nutrients, rather than extracts or isolated chemical replications in a pill or capsule. My hesitancy about eating a lot of fish, however, is because of concerns about mercury levels. While commercially available fish is generally considered safe, mercury is frequently present at low levels. Extracted fish oil can (and should) be micro-filtered, molecularly distilled and tested for heavy metals, PCBs, dioxins and furans, microbial contaminants, oxidation and rancidity. In addition, it can be standardized for optimal levels of EPA and DHA, which are believed to be the most active components.
At toxic levels, mercury can cause reproductive problems, tremors and memory dysfunction in adults. For infants and fetuses, exposure can cause deafness, blindness and mental retardation. The biggest single source of mercury is the burning of coal in power plants. This accounts for about 40% of the mercury that affects humans. Other contaminating activities are the burning of hazardous waste, chlorine production, and the breaking and/or improper disposal of mercury containing products.
Two of the favorite “oily” fish for consumption are the (salt water) salmon and (fresh water) trout, but shark, tuna and swordfish are other popular choices. The problem with those large carnivorous fish is that mercury tends to accumulate at the top end of the food chain: indeed the difficulty in ridding it from the body is part of why it is such a harmful contaminant.
Recently, however, a study by the US Geological Survey found a prevalence of mercury in fresh water fish of the United States as well. Traces of methymercury – a form that is easily absorbed – were found in every fish sampled in the 291 streams that were tested around the country. Worse, the level of mercury detected exceeded the level considered safe for human consumption (as established by the EPA) in about a quarter of those fish. For smaller fish-eating mammals the news was even more alarming – about two-thirds of the tested sites had mercury levels that were considered excessive for their consumption.
In addition to alerting us about an aspect of our food supply, this news about our fresh water environments speaks to the need for tighter environmental protection policies. We cannot always see such a clear connection between human activity and its impact on a large and important food source. Here is a case where government policies can be directed to make a distinct improvement in our nutritional health, as well as benefiting the environment as a whole.
