Tuesday, May 6, 2008

A nutritional fish story

When Sir William Gilbert, lyricist to songsmith Sir Arthur Sullivan, wrote, “Here’s a pretty kettle of fish!” he may well have been talking about the latest skinny on seafood.
The good news from a 2002 Harvard survey of more than 43,000 male health professionals shows that the ones who eat 3 to 5 ounces of fish just once a month have a 40 percent lower risk of ischemic stroke, a stroke caused by a blood clot in a cranial artery. The Harvard study did not include women, but a report on women and stroke published in the Journal of the American Medical Association in 2000 says that women who eat about 4 ounces of fish — think one small can of tuna — two to four times a week appear to cut their risk of stroke by a similar 40 percent.
These benefits are, in large part, because of the presence of omega-3 fatty acids, which are unsaturated fatty acids found most commonly in fatty fish such as salmon and sardines. The primary omega-3 is alpha-linolenic acid, which your body converts to hormonelike substances called eicosanoids. The eicosanoids—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — reduce inflammation, perhaps by inhibiting an enzyme called COX-2, which is linked to inflammatory diseases such as rheumatoid arthritis (RA). The Arthritis Foundation says omega-3s relieve RA joint inflammation, swelling, and pain.
Omega-3s also are heart-friendly. The fats make the tiny blood particles called platelets less sticky, reducing the possibility that they’ll clump together to form blood clots that might obstruct a blood vessel and trigger a heart attack. Omega-3s also knock down levels of bad cholesterol so effectively that the American Heart Association recommends eating fish at least twice a week. Besides, fish also is a good source of taurine, an amino acid the journal Circulation notes helps maintain the elasticity of blood vessels, which means that the vessels may dilate to permit blood or — horrors! — a blot clot to flow through.
Did I mention that omega-3s are bone builders? Fish oils enable your body to create calciferol, a naturally occurring form of vitamin D, the nutrient that enables your body to absorb bonebuilding calcium — which may be why omega-3s appear to help hold minerals in bone — and increase the formation of new bone.

Consumer Alert No. 1
Before you shout, “Waiter! Bring me the salmon, mackerel, herring, or whatever,” here’s the other side of the coin. Earlier research suggests that frequent servings of fish may increase the risk of a stroke caused by bleeding in the brain. This situation is common among Native Alaskans who eat plenty of fish and have a higher than normal incidence of hemorrhagic, or bleeding, strokes. True, the Harvard study found no significant link between fish consumption and bleeding strokes, but researchers say more studies are needed to nail down the relationship — or lack thereof.

Consumer Alert No. 2
Not all omegas are equally beneficial. Omega-6 fatty acids — polyunsaturated fats found in beef, pork, and several vegetable oils, including corn, sunflower, cottonseed, soybean, peanut, and sesame oils — are chemical cousins of omega-3s, but the omega-6s lack the benefits of the omega-3s.

Consumer Alert No. 3
Wait! Don’t go just yet. Despite all the benefits fish bring to a healthful diet, I want to remind you that some fish, particularly those caught in the wild (rather than raised on a fish farm), may be contaminated with metals such as mercury, which has made its way into the water as industrial pollution and may be hazardous for women who are or may be pregnant. Check the food bulletins in your local newspaper or check the FDA’s hotline for the most up-todate data.
Now it’s really a pretty kettle of fish!

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