Now a University of Michigan biochemist reports that fish oil significantly diminishes the production and effectiveness of various prostaglandins, naturally occurring hormone-like substances that can accentuate inflammation and thrombosis.

Dr. William L. Smith described his findings on April 4 at Experimental Biology 2006 in San Francisco. His presentation was part of the scientific program of the American Society for Biochemistry and Molecular Biology (ASBMB).

Dietary fish oil causes its prostaglandin-lowering effects through three different mechanisms, says Dr. Smith.

First, the much fewer prostaglandins are made from omega 3 fatty acids as compared to the other class of fatty acids in the body, the omega 6 family of fatty acids that originate in the diet from leafy vegetables and other plant sources.

Second, the omega 3 fatty acids compete with omega 6 fatty acids for the same binding site on the COX 1 enzyme that converts the omega 6 fatty acids to prostaglandin (which is why the COX 1 enzyme and its COX 2 cousin are the targets of anti-inflammatory drugs like ibuprofen). The more omega 3 fatty acids present to block the binding sites, the fewer omega 6 fatty acids are able to be converted to prostaglandin.

Third, although omega 3 fatty acids also are converted to prostaglandins, the prostaglandins formed from omega 3 are generally 2 to 50 times less active than those formed from the omega 6 fatty acids from dietary plants.

The biochemical basis of other benefits of dietary fish oil  for example, omega 3 fatty acids' impact on neuronal development and visual acuity -- are probably due to effects on biochemical pathways regulating nerve transmission. Understanding the different pathways through which omega 3 works to convert prostaglandin helps explain why the plant-based omega 6 fatty acids don't simply provide the same benefits. Because of omega 3 fatty acids' known benefits to health, especially cardiovascular health, Dr. Smith's advice is simple: eat more fish.

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White teens who reported that their parents did not approve of them having sex at this age were less likely to have engaged in pre-coital sexual behavior.

Both black and white youth who reported their parents did not want them to have sex were less likely to have engaged in sexual intercourse by the time they were 16 years old than those who perceived less parent disapproval of teen sex.

Brown said the media, schools, parents and pediatricians need to provide more accurate and timely sexual information to teens, otherwise, the media will continue to serve as a kind of sexual super peer that doesn't have the best interests of young people in mind.

As she says, it took many studies over a number of years to establish that violence in the media increased children's violent behaviour and to begin initiatives to reduce harmful effects.

Therefore, the researchers say, it may be prudent not to wait decades to conclude that the media are also important sources of sexual norms for youth.

The study was published in the April issue of Pediatrics, the journal of the American Academy of Pediatrics.