Heart patients have long been told to eat a diet rich in fish, nuts and other sources of omega-3 fatty acids. Now, researchers think they know exactly why the diet is so beneficial.
A number of studies have shown that fish oil and omega-3s can reduce the risk of heart attacks or heart disease. What has not been clear is why. So scientists decided to find out by looking deep into the blood cells of heart disease patients, focusing on their telomeres.
Telomeres are the caps on the ends of chromosomes that protect the valuable genetic material within. There's growing evidence that telomere length is a marker for biological age, so that long telomeres are a sign of younger, healthy cells, and short telomeres are a sign of either normal aging, or premature aging caused by disease and poor lifestyle.
For this latest study, Dr. Ramin Farzaneh-Far, of the University of California, San Francisco, and colleagues measured omega-3 fatty acid levels in the blood of more than 600 patients with stable heart disease. They then compared those levels to changes over five years in telomere length in leukocytes, a type of blood cell.
They found that those with the highest levels of omega-3 fatty acids in their blood had the longest telomeres.
"Patients with the highest levels of omega-3 fish oils were found to display the slowest decrease in telomere length, whereas those with the lowest levels of omega-3 fish oils in the blood had the fastest rate of telomere shortening, suggesting that these patients were aging faster than those with the higher fish oil levels in their blood," he explained.
"These findings raise the possibility that omega-3 fatty acids may protect against cellular aging in patients with coronary heart disease," the researchers write in the study, which appears in JAMA, the Journal of the American Medical Association.
The researchers didn't give the patients omega-3 supplements nor did they collect dietary information, so it is not clear just how much fish oil it took to have an effect. But the researchers say the study offers a good biological explanation for why fish oil helps heart patients.
They note that they're still not sure why the omega-3s protect telomeres. It may be that they help prevent oxidative stress, which damages cells and their DNA. Or it may be that fish oil increases the production of telomerase -- an enzyme that lengthens and repairs telomeres.
Further research is needed, Farzaneh-Far says, on the exact mechanism.
Still, his team says the bottom line message is that heart disease patients should continue to try to get at least one gram of omega-3s in their diet every day.
Omega-3s are found most abundantly in fatty fish, such as salmon, but they are also in nuts, sunflower and flax seeds and other sources.
