Higher blood levels of omega 3 fatty acids found in seafood are associated with a higher likelihood of healthy ageing among older people, according to a study published by the BMJ.
With populations across the world living longer, there is a growing focus on healthy ageing – a meaningful lifespan without major chronic diseases and with good physical and mental function. While lifespans are increasing in most countries, healthy lifespans are not.
Previous studies suggest omega 3 polyunsaturated fatty acids (known as n-3 PUFAs) derived from seafood and plants may have beneficial effects on the body that could promote healthy ageing, but results were inconsistent.
Similarly, other studies suggested they help to reduce the risk of cardiovascular events – such as heart attack or stroke –in high-risk patients, but again some fish oil supplement studies have failed to support claims of preventing heart attacks, strokes or any vascular disease.
A team of US researchers, led by Heidi Lai at Tufts University in Boston, set out to investigate the association between circulating blood levels of n-3 PUFAs and healthy ageing among older adults.
The study, published on Wednesday, involved 2,622 adults who were taking part in the US Cardiovascular Health study from 1992 to 2015. Average age of participants at the start of the study was 74 years; 63 per cent were women.
Blood levels of n-3 PUFAs were measured regularly over 13 years. These included its main forms commonly known as EPA, DHA, DPA and ALA. The main dietary sources of EPA, DHA and DPA come from seafood, while ALA is found mainly in plants (nuts, seeds, and leafy green vegetables).
Participants were graded into five groups from lowest to highest with circulating blood n-3 PUFA levels. Through review of medical records and diagnostic tests, the researchers found 89 per cent of participants experienced unhealthy ageing over the study period, while 11 per cent experienced healthy ageing; defined as survival free of major chronic diseases and without mental or physical dysfunction.
Unhealthy ageing
After taking account of a range of other social, economic, and lifestyle factors, the researchers found levels of seafood-derived EPA in the highest group were associated with a 24 per cent lower risk of unhealthy ageing than levels in the lowest.
For DPA levels, the top three groups were associated with an 18 to 21 per cent reduction in the risk of unhealthy ageing. However, seafood-derived DHA and plant-derived ALA were not associated with healthy ageing.
A possible explanation for this effect is n-3 PUFAs help to regulate blood pressure, heart rate and inflammation, the authors explain.
They point out this was an observational study, so no firm conclusions can be drawn about cause and effect and they cannot rule out the possibility some of the observed risk may be due to other factors.
The study had a long (up to 22 years) follow-up period, and results remained largely unchanged. As such, they say among older adults “higher levels of circulating n-3 PUFAs from seafood were associated with a lower risk of unhealthy ageing”.
“These findings encourage the need for further investigations into plausible biological mechanisms and interventions related to n3-PUFAs for maintenance of healthy ageing, and support guidelines for increased dietary consumption of fish among older adults,” the authors conclude.
In an editorial, Prof Yeyi Zhu and colleagues at the University of California say the study makes a valuable contribution to an understanding of the effect n3-PUFAs might have on ageing. But they caution against using the findings to inform public health policy or nutritional guidelines.
“Following the World Health Organization’s policy framework for healthy ageing, any evidence-based clues to improve health in later life are welcome but additional efforts to accelerate this area of research are essential,” they add.
