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Omega 3 from seafood linked to healthier ageing

Higher levels of circulating n-3 PUFAs from seafood associated with lower risk of unhealthy ageing

Louise Prime

Thursday, 18 October 2018

Older people with higher blood levels of omega 3 fatty acids from seafood were more likely to live for longer free from major chronic diseases and mental or physical dysfunction, supporting current guidelines that older adults should increase their consumption of seafood, according to the authors of the study*, published today in the BMJ. However, experts cautioned against using the findings to inform public health policy or nutritional guidelines, without further research.

US researchers conducted a prospective cohort study to determine the longitudinal association between serial biomarker measures of circulating omega 3 polyunsaturated fatty acid (n3-PUFA) levels and “healthy ageing” – living a meaningful lifespan without chronic diseases, and with intact physical and mental function.

Their subjects were 2,622 women and men from four communities in the US who were participating in the Cardiovascular Health Study; their mean age was 74.4 years and all showed successful healthy ageing at baseline in 1992-93. At baseline, and at six and 13 years, participants’ blood levels of n3-PUFAs were measured. These included eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) – whose main dietary source is seafood – and α-linolenic acid (ALA), found mainly in nuts, seeds, and leafy green vegetables.

The researchers found that higher levels of long chain n3-PUFAs were associated with an 18% lower risk of unhealthy ageing per interquintile range after multivariable adjustments with time-varying exposure and covariates. Individually, higher EPA and DPA (but not DHA) levels were associated with a lower risk: 15% and 16%, respectively. There was no statistically significant association between ALA from plants and unhealthy ageing (hazard ratio 0.92).

After adjusting for other social, economic, and lifestyle factors, they also found that levels of seafood-derived EPA in the highest quintile were associated with a 24% lower risk of unhealthy ageing than levels in the lowest quintile. They suggested that their results might be explained by n3-PUFAs’ regulation of blood pressure, heart rate and inflammation.

They acknowledged that their study was observational and so could not show cause and effect, but said that its strengths included its long follow-up period with regular clinical physical examinations, their tight definition of “healthy ageing”, and its generalisability because it was community-based.

They concluded: “These findings support guidelines for increased dietary consumption of n3-PUFAs in older adults.”

The authors of an accompanying editorial** agreed that the study makes a valuable contribution to this area, by combining reported dietary data with repeated measurements of biomarkers to account for trends over time in individual n3-PUFAs; but they called for further research in populations with more diverse dietary patterns.

They said: “Epidemiologic associations cannot infer [sic] causality, so, we caution against using these findings to inform public health policy or nutritional guidelines. … any evidence-based clues to improve health in later life are welcome, but additional efforts to accelerate this area of research are essential.”

*Lai HTM, de Oliveira MC, Lemaitre RN, et al. Serial circulating omega 3 polyunsaturated fatty acids and healthy ageing among older adults in the Cardiovascular Health Study: prospective cohort study. BMJ 2018; 363: k4067 doi: 10.1136/bmj.k4067.
**Zhu Y, Ferrara A, Forman MR. Editorial: Omega 3 polyunsaturated fatty acids and healthy ageing. BMJ 2018; 363: k4263 doi: 10.1136/bmj.k4263.

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