What the Seafood Consumer Needs to Know About Omega-3's and Mercury

The same dilemma occurs every evening: what kind of easy, nutritious meal shall I prepare for dinner?  Tuna casserole seems to be my comfort food of choice. Tuna casserole is nutritious, easy to prepare, and usually a hit with everyone assembled at the dinner table. The nutrition panel on the label of my large can of albacore tuna boasts of a plethora of nutrients, among them niacin, vitamins B6 and B12, vitamin D and selenium. Tuna, like all seafood also contains essential omega-3 fats. Canned tuna is possibly the most perfect inexpensive food. While preparing my tuna casserole, I cannot help but think about an environmental toxin lurking inside my can of albacore: methyl mercury. Mercury, or any mention of mercury, is clearly absent from the product label.

Both the United States Department of Agriculture (USDA) and The American Heart Association (AHA) recommend that we consume at least 2-3 servings (8 ounces) of seafood per week to assure that we obtain a healthy dose of omega-3 fats. Omega-3 fats are touted for their widespread health benefits: lowering blood pressure, reducing triglycerides, slowing the development of cardiac disease by reducing plaque in arteries, and anti-inflammatory properties as well.  Nutritional aspects aside, one persistent question remains in the mind of every seafood consumer. Just how much mercury is present in my can of tuna or other seafood that I consume?

According to the USDA, white albacore tuna contains some of the highest levels of mercury--40 mcg/4 ounce serving--three times the amount in "light" canned tuna. Conversely, salmon (all varieties) contains some of the lowest levels of mercury to be found in any seafood--2 mcg/4 ounce serving. The primary safety concern over mercury is its potential risk to infants and unborn children. If consumed in high enough quantities by their mothers, mercury can impair neurological development in the brains of developing fetuses during gestation, as well as infants who breast feed postpartum.

The key is to weigh the benefits against the risks of seafood consumption. USDA-conducted studies conclude that the health benefits derived from moderate consumption of cooked seafood outweigh the risk associated with mercury, including women who may become or are pregnant, nursing mothers, and children ages 12 and younger.  However, the Federal advisory board specifically states that these groups should not eat or should limit their intake of large predatory fish. Predatory fish--sharks, tilefish, swordfish, and mackerel--are known to contain excessively high levels of mercury in their flesh.

Another option for those who choose not to consume fish is to take omega-3 fish oil supplements. Interestingly, no studies have been conducted by the USDA on omega 3 supplements and their potential to also contain mercury.  Truth is, supplements of any kind are taken by consumers in blind faith. The Food and Drug Administration (FDA) mandates that the label of all supplement bottles (omega-3's, vitamins, minerals) include the following disclaimer: "This statement has not been evaluated by the Food and Drug administration. This product is not intended to diagnose, treat, cure, or prevent any disease.” The reason for this government disclaimer is because the supplement industry is widely unregulated. Manufacturers and distributors do not need FDA approval to sell their dietary supplements, including fish oil.  The government does not analyze supplements to assure their quality or purity. This lack of regulatory control in the billion dollar supplement industry leaves the consumer in the dark to wonder if that hefty dose of omega-3's in pill form is also contaminated with mercury. Just because the label says so does not necessarily mean so.

Again, moderation is the key to proper nutrition. Too much of one thing is not a good thing. For maximum nutritional benefits from seafood, the USDA recommends the selection of seafood species that are higher in omega-3 fatty acids while lower in contaminants such as mercury. An informed consumer is the best consumer.

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