Oils from fish have been touted for years as elixirs of health; think cod liver oil in Victorian novels. More recently, fish oil, and specifically omega-3 fatty acids, have contributed to the demise of legions of cold-water fish. Now a study in JAMA, Association of Marine Omega-3 Fatty Acid Levels With Telomeric Aging in Patients With Coronary Heart Disease* (see conclusions from this article in JAMA below) is likely to accelerate the carnage.
This study is a fascinating demonstration of 'bench to bedside' medicine, something embraced at Johns Hopkins. Telomeres are the ends of chromosomes, presumably there to protect the actual business DNA of the cell each time it divides. It's been known for some time that as cells divide over the course of the lifetime of an organism, the telomeres get shorter. Nobel laureate Carol Greider, a member of the faculty at Johns Hopkins, was cited for her work on telomerase, an enzyme that is involved with preservation of telomeres.
Now it turns out that fish oils help preserve telomere length. The authors of this study thought that might be the case and developed the hypothesis that telomere preservation may account for the protective effects of fish oils in patients with cardiovascular disease. They looked at levels of omega-3 fatty acids in over 600 patients with known coronary artery disease and measured blood levels of the two primary omega-3 fatty acids, and assessed telomere length over a five year period. They found that those participants with the highest levels of the omega-3s had the longest telomeres.
Another interesting finding was that those who had the longest telomeres at the beginning of the study experienced the greatest benefit from omega-3s in terms of preservation. What this suggests to me is that it's good to start early in terms of fish oil consumption.
Lots of questions remain, of course, especially the supplement versus dietary consumption of fatty acids, but the impact of telomere length on aging and disease is something we expect to hear more and more about.
* FROM the JAMA STUDY
Conclusion Among this cohort of patients with coronary artery disease, there was an inverse relationship between baseline blood levels of marine omega-3 fatty acids and the rate of telomere shortening over 5 years.
Multiple epidemiologic studies, including several large randomized controlled trials, have demonstrated higher survival rates among individuals with high dietary intake of marine omega-3 fatty acids and established cardiovascular disease. On this basis, the American Heart Association recommends increased oily fish intake and the use of omega-3 fatty acid supplements for the primary and secondary prevention of coronary heart disease. The mechanisms underlying this protective effect are poorly understood but are thought to include anti-inflammatory, antiplatelet, antihypertensive, antiarrhythmic, and triglyceride-lowering effects. There is ongoing interest in the identification of novel mechanisms of cardiovascular benefit from omega-3 fatty acids.
Telomeres are tandem repeat DNA sequences (TTAGGG)n that form a protective cap at the ends of eukaryotic chromosomes.7 During somatic cell division, DNA polymerase cannot fully replicate the 3′ end of linear DNA, resulting in an obligate and progressive loss of telomeric repeats. This process may eventually result in cellular senescence or apoptosis. These observations have led to telomere length emerging as a novel marker of biological age, which integrates the cumulative lifetime burden of genetic factors and environmental stressors independent of chronological age. Moreover, a robust association between short telomeres and cardiovascular morbidity and mortality has been documented in several populations.
Little is known concerning the dynamic regulation of telomere length over time, although it has recently become apparent that telomeres may lengthen as well as shorten. Given the cardioprotective effects of omega-3 fatty acids, we sought to determine whether omega-3 fatty acid levels were associated with changes in leukocyte telomere length over 5 years in a prospective cohort study of outpatients with coronary artery disease.
The American Heart Association recommends that healthy adults eat fish at least twice weekly. Fatty fish such as catfish, halibut, salmon, striped sea bass, and albacore tuna are particularly recommended. Plant-based sources of ALA such as tofu, walnuts, and canola oil are also recommended. The World Health Organization recommends a daily EPA and DHA intake of 0.3-0.5 grams and a daily ALA intake of 0.8-1.1 grams.