In part, that's because of these fats' damping effect on chronic, "silent” inflammation… a key accelerator of human aging.
But the results of a new study suggest that may also act to protect our DNA from decay… a fundamental level in the fight against premature aging.
Today's story was foreshadowed late last summer, when researchers linked tea and multivitamins to slower aging in our cells.
In both cases, the scientists looked at the length of DNA sequences at the end of chromosomes—called "telomeres”—that shorten as cells replicate and age.
Those studies showed that two daily routines—drinking tea or taking a multivitamin pill—were associated with having longer telomeres, compared with people who had neither habit.
Now, researchers have shown that omega-3s may also protect telomeres… at least in heart patients.
Findings add fish-borne omega-3s to list of telomere protectors
Researchers based at the University of California conducted a study designed to determine whether omega-3 blood levels were associated with changes in telomere length among heart patients with coronary artery disease (Farzaneh-Far R et al. 2010).
Specifically, they compared the lengths of telomeres in the participants' leukocytes—a type of blood cell—at the beginning and end of a five-year period.
A team led by Ramin Farzaneh-Far, M.D., recruited 608 heart patients between September 2000 and December 2002, and measured the length of their leukocyte telomeres at the beginning of the study and again after five years of follow-up.
After comparing the starting lengths of the cardiac outpatients' telomeres with their length after five years, the researchers found that people with the lowest omega-3 levels experienced the speediest rate of telomere shortening.
In contrast, those with the highest omega-3 levels showed the slowest rate of telomere shortening.
As the authors wrote, "…there was an inverse relationship between baseline blood levels of marine omega-3 fatty acids and the rate of telomere shortening over 5 years. These findings raise the possibility that omega-3 fatty acids may protect against cellular aging in patients with coronary heart disease” (Farzaneh-Far R et al. 2010).
And they calculated the precise relationship between the heart patients' omega-3 levels and the rate of their telomere shortening: "Each 1-SD increase in DHA+EPA levels was associated with a 32 percent reduction in the odds of telomere shortening” (Farzaneh-Far R et al. 2010).
Results may help explain omega-3s' proven heart benefits
The findings offer one plausible biological explanation for why fish oil helps heart patients.
The authors speculated that omega-3s may counteract oxidative stress, or increase the production of telomerase… an enzyme that lengthens and repairs shortened telomeres.
If you find it surprising that they'd suggest an antioxidant role for omega-3s, you've been listening to the wrong people.
Many observers make erroneous assumptions about the susceptibility of dietary omega-3s to oxidation in the body.
While omega-3s oxidize rapidly when exposed to air, several recent studies have shown that they act as antioxidants inside our vascular system… thereby reducing inflammation and, in turn, the risk of atherosclerosis and cardiovascular disease (Higdon JV et al. 2000; Wander RC et al. 2000; Richard D et al. 2008).
The researchers only studied the effects of fish oil on cellular aging in heart patients, so it is not clear if the association would hold true in healthy people.
But as Dr. Farzaneh-Far told Reuters, "There is no reason to think that it wouldn't.”
He expressed the essence of his team's finding this way:
"Telomere length is an emerging marker for determining biological age… We are excited to identify omega-3 fatty acids as a potentially protective factor that may slow down telomere shortening” (UCSF 2010).
Farzaneh-Far R, Lin J, Epel ES, Harris WS, Blackburn EH, Whooley MA. Association of Marine Omega-3 Fatty Acid Levels With Telomeric Aging in Patients With Coronary Heart Disease. JAMA. 2010;303(3):250-257.
Xu Q, Parks CG, DeRoo LA, Cawthon RM, Sandler DP, Chen H. Multivitamin use and telomere length in women. Am J Clin Nutr. 2009 Jun;89(6):1857-63. Epub 2009 Mar 11.
Chan R, Woo J, Suen E, Leung J, Tang N. Chinese tea consumption is associated with longer telomere length in elderly Chinese men. Br J Nutr. 2009 Aug 12:1-7. [Epub ahead of print]
Reuters. Fish oil protects against cellular aging: study. January 19, 2010. Accessed at http://www.reuters.com/article/idUSTRE60I5L220100119
University of California, San Francisco (UCSF). January 20, 2010. Accessed at http://news.ucsf.edu/media-coverage/details/national-international-news-highlight-ucsf-study-on-telomeres-and-omega-3-f/
Higdon JV, Liu J, Du SH, Morrow JD, Ames BN, Wander RC. Supplementation of postmenopausal women with fish oil rich in eicosapentaenoic acid and docosahexaenoic acid is not associated with greater in vivo lipid peroxidation compared with oils rich in oleate and linoleate as assessed by plasma malondialdehyde and F(2)-isoprostanes. Am J Clin Nutr. 2000 Sep;72(3):714-22.
Richard D, Kefi K, Barbe U, Bausero P, Visioli F. Polyunsaturated fatty acids as antioxidants. Pharmacol Res. 2008 May 18. [Epub ahead of print]
Thies F, Garry JM, Yaqoob P, Rerkasem K, Williams J, Shearman CP, Gallagher PJ, Calder PC, Grimble RF. Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial. Lancet. 2003 Feb 8;361(9356):477-85.
Wander RC, Du SH. Oxidation of plasma proteins is not increased after supplementation with eicosapentaenoic and docosahexaenoic acids. Am J Clin Nutr. 2000 Sep;72(3):731-7.