Our 'body age' can often be much older than our actual age - and scientists have finally hit on the key factor that may determine biological ageing. They have discovered that people with higher levels of omega-3 fatty acid in their blood are younger biologically than their physical years. Omega-3, which is found in fatty fish but which can also be taken as a supplement, seems to have a protective effect against cellular ageing, researchers at the University of California, San Francisco have found. It's already known that people who take omega-3 supplements survive longer, even when they have a heart problem, but the research team now think they are beginning to understand why. It's all to do with telomeres, which are chromosome markers of cellular ageing; if they begin to shorten, it's an indication that our cells are getting old and are even dying. In a study of 608 patients with a heart condition, the researchers found that the heart patients who were living longer had higher levels of the fatty acid in their blood, and had longer telomere chromosomes. (Source: Journal of the American Medical Association, 2010; 303: 250-7).