More accolades for omega 3’s

Omega-3’s are emerging superheroes in the nutrition world. Over two decades ago, scientists noticed that Greenland Eskimos had very low rates of coronary heart disease compared to Western populations. Their secret, it turned out, was eating fish—particularly, fatty fishes like salmon that contain a lot of omega-3 fatty acids.

An avalanche of studies have since demonstrated the cardiovascular health benefits of omega-3 fatty acids, also found in flax seeds and walnuts, as well as suggesting benefits in combating depression, rheumatoid arthritis and some types of cancer, and in boosting cognitive function.

And now comes more evidence that they can prevent blindness. In 2007, a study led by Children’s ophthalmologist Lois Smith revealed that omega-3 fatty acids protect mice against retinopathy, a major form of blindness caused by abnormal growth of blood vessels in the eye. It affects over 4 million Americans with diabetes and many premature infants. A related disease, a form of age-related macular degeneration called “wet AMD” also involves abnormal growth of blood vessels and affects over 7 million older Americans.

At left, a normal mouse retina; at right, abnormal blood vessel growth in a mouse with retinopathy. An omega-3-based diet dampened abnormal vessel growth, which, if unchecked, can cause retinal detachment and blindness.

Now, new research from Smith’s team shows that omega-3s’ protective effect is two-pronged. The initial study found that omega-3’s reduce inflammatory signaling. The new study finds a further benefit: omega-3’s seem to selectively promote the growth of healthy blood vessels and block the growth of abnormal (often tortuous and leaky) blood vessels.

Smith’s team also identified the specific component of omega-3’s responsible for this magic: a metabolite called 4-HDHA, produced by the enzyme 5-lipoxygenase.

Better understanding the biochemistry of how omega 3’s work helped eliminate the concern that COX enzymes are involved—curbing worries that common COX-inhibiting drugs like ibuprofen and aspirin (frequently taken to prevent heart disease) might negate the benefits of omega-3’s.

The study even suggests that omega-3’s may be worth considering in the treatment of diabetes: the enzyme that metabolizes them activates the same receptor targeted by “glitazone” drugs like Avandia used in type 2 diabetes.

Smith is now collaborating with a group in Sweden that is conducting a clinical trial of omega-3 fatty acids in premature infants, who are often deficient in omega-3’s and at risk for retinopathy. If results are promising, Smith will seek FDA approval to conduct a similar trial in premature infants at Children’s.

A multicenter trial of omega-3 supplements, known as AREDS2, is already underway in patients with AMD and will continue until 2013. A prior retrospective study, AREDS1, found higher self-reported intake of fish to be associated with a lower likelihood of AMD.

Despite fish being one of my least favorite foods, I have to admit that the evidence of its benefits is pretty compelling. Next time I come across some grilled salmon or albacore tuna, I won’t turn it down. Maybe I’ll even add some flax seed to my breakfast and make my mom proud.