October 05, 2009
Mercury From Fish Boosts Blood Pressure

Mercury is bad. If we got more electricity from nuclear power rather than coal we'd put less mercury into the environment.

DALLAS, Oct. 5, 2009 The negative impact of high amounts of methylmercury in seafood on blood pressure may outweigh the protective effects of fish nutrients, researchers report in Hypertension: Journal of the American Heart Association.

Researchers found that even when blood pressure was within the normal range and numerous other factors, including omega-3 fatty acids (essential fats that your body needs to function properly but does not make) and selenium (a dietary essential mineral) were carefully controlled for, the environmental mercury was associated with higher blood pressure and pulse pressure among Nunavik Inuit adults in a recent study.

Keep in mind that few eat as much fish as the Nunavik.

Researchers conducted a survey in the 14 Nunavik communities in northern Quebec, Canada, where the traditional diet is based mainly on fish and marine mammals, and thus, residents regularly ingest higher levels of environmental mercury. Individuals taking medication for high blood pressure during data collection were excluded. The survey featured two-stage stratified random sampling and data from 732 Inuit adults (319 men and 413 women), average age 34.

The average total mercury blood concentration in people in the United States is now 4 nanomoles per liter (nmol/L) (NHANES study) compared to 50 nmol/L in the Inuit population.

Higher blood mercury means higher blood pressure.

Researchers found a 10 percent increase in blood mercury was associated with an increase of 0.2 mm Hg in systolic blood pressure after controlling for other factors.

You can get lots of omega 3 fatty acids by eating fish that have almost undetectable amounts of mercury such as sardines and salmon. Check out this US Food and Drug Administration chart of mercury levels in fish. The big fish at the top of the food chain such as shark and swordfish have high mercury levels. Compare them to tilapia and oysters. Salmon are the best to eat to my thinking because they have very low mercury while having some of the highest levels of omega 3 fatty acids such as DHA.

A study back in April 2009 found that consumption of one portion of fatty fish per week cut men's risk of heart failure.

BOSTON Eating salmon or other fatty fish just once a week helped reduce men's risk of heart failure, adding to growing evidence that omega-3 fatty acids are of benefit to cardiac health. Led by researchers at Beth Israel Deaconess Medical Center (BIDMC) and reported in today's on-line issue of the European Heart Journal, the findings represent one of the largest studies to investigate the association.

"Previous research has demonstrated that fatty fish and omega-3 fatty acids help to combat risk factors for a range of heart-related conditions, such as lowering triglycerides [fats in the blood] reducing blood pressure, heart rate and heart rate variability," explains first author Emily Levitan, PhD, a research fellow in the Cardiovascular Epidemiology Research Center at BIDMC. "Collectively, this may explain the association with the reduced risk of heart failure found in our study."

Studies of fish consumption are problematic because they typically do not collect detailed information about the types of fish consumed. Well, omega 3 fatty acid levels vary considerably between types of fish.Omega 3 fatty acid levels in fish vary over a few orders of magnitude. Caviar is the best followed by salmon.

There might be an ideal daily dose of omega 3 fatty acids.

The findings were similar when the researchers looked at fish oil consumption: Among five groups based on fish oil consumption, the middle group, who consumed 0.36 grams per day of omega-3 fatty acids showed a 33 percent reduced risk of heart failure, while the men who consumer greater quantities (approximately 0.46 grams per day or 0.71 grams per day) had a risk of heart failure similar to the men who consumed little or no fish oils.

Though the researchers leave open the possibility that people suffering from heart disease up their omega 3 fatty acid intake to help treat their disease. So the lack of benefit from the larger dose might not be real.

Share |      Randall Parker, 2009 October 05 11:42 PM  Aging Diet Heart Studies


Comments
Brett Bellmore said at October 6, 2009 4:00 AM:

Standardized fish oil is the best source of Omega 3s. It's the only way to be certain how much you're getting, that you're not getting mercury along with it, and it's the affordable way to get omega 3s, too. And it can be incorporated into a wide variety of foods, from ice cream to baked goods.

Admittedly, I LIKE salmon, but that doesn't change the economics.

Wolf-Dog said at October 6, 2009 11:45 PM:

I have read that fish oil that is molecularly distilled, happens to be absolutely free from any toxic metals.

Probably, even non-molecularly distilled fish oil would contain a lot less mercury than the fish itself, since the mercury is probably accumulated in the cells.

Thus if you get salmon oil from the vitamin store, this would probably be much better than eating the salmon itself. If the salmon oil is from Alaska or Norway, or even better if the salmon oil is molecularly distilled, then you are very safe. I definitely feel good when I take salmon oil tablets.

fitguy said at November 2, 2009 4:50 AM:

Heavy metals including mercury accumulate in the flesh of fish not the oil. All fish oil has negligible heavy metal content.

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