Higher serum levels of circulating omega 3 polyunsaturated fatty acid (n3-PUFA) are linked to increased survival without chronic diseases and cognitive and physical dysfunction reports the results of a new study published online October 17 in BMJ.
Fish-oil and long-chain omega-3 fatty acids (EPA, DPA, and DHA) are well known for their role in human well-being. As evident through many previous studies, omega-3 fatty acids are involved in maintaining cardiovascular health, but their role in overall healthy aging is not well established.
This study is unique because unlike previous studies, the researchers from Tuft’s University did not solely rely on dietary history but serially measured the levels of biomarkers in blood. Long chain omega-3s in human diets are primarily derived from seafood, fish oil supplements, and foods fortified with fish oils while the shorter-chain omega-3s, like α-linolenic acid (ALA), are predominantly sourced from plants.
Adults with higher levels of n3-PUFA derived from seafood {eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA)} was associated with an 18% lower risk of unhealthy aging because of lower incidence of chronic diseases that include cardiovascular diseases, chronic kidney disease, lung disease, and cancer.
Surprisingly, α-linolenic acid from plants did not offer the same protection against healthy aging as those derived from seafood (hazard ratio 0.92, 95% confidence interval 0.83 to 1.02).
The study participants were sampled from a pool of 5888 adults enrolled in the Cardiovascular Health Study across 4 centers in the US. CHS is a population-based, longitudinal study to identify the risk factors related to the onset of coronary heart disease and stroke in US adults aged 65 years and older.
The researchers recruited 2622 healthy adults at baseline with a mean age 75 years and measured plasma phospholipid n3-PUFAs at three-time points over a 13-year period (1992/93, 1998/99, and 2005/06) to account for trends over time. Researchers measured cumulative levels of plasma phospholipid n-3 PUFAs using gas chromatography and expressed it as a percentage of total fatty acids.
Sociodemographic information gathered included age, gender, ethnicity, education, and income. Risk factors measured at each visit include dietary habits and intake, alcohol intake, body mass index, physical activity (excluding chores), blood pressure, lipids, lipid-lowering drugs, and smoking status.
Participants were also asked about self-perceived general health, family history of myocardial infarction or stroke, hypertension, osteoporosis, depression, and arthritis.
Only 10% of the study population was non-white, and the majority (64%) were women. Those with higher blood levels of long-chain n-3 PUFAs were more likely to be female, well educated, from higher income group and leading a healthier lifestyle in general and consumed an additional serving of fish as compared to those with lower levels.
At the start of the study, n-3 PUFA levels were comparable between healthy agers and unhealthy agers. During 21 803 person-years of follow-up, 2330 (89%) participants did not age well, and 292 (11%) experienced healthy aging (positive deviance).
After taking into account the various demographic, medical and lifestyle confounders, participants with the highest long-chain n-3 PUFA levels were associated with 18% lower likelihood of unhealthy aging, as compared to those with lower levels.
When the researchers analyzed for individual n-3 PUFA, they found that individuals in the highest EPA or DPA groups had 24% and 18% lower risk of unhealthy aging as compared to those in the lower group. This protection was not provided by plant-based α-linolenic acid or docosahexaenoic acid (DHA).
In linear regression models, higher levels of long-chain n3-PUFAs, but not α-linolenic acid, were consistently associated with a lower likelihood of unhealthy aging.
Yeyi Zhu, Ph.D., MS, research scientist, Division of Research, Kaiser Permanente Northern California, and assistant adjunct professor, Department of Epidemiology & Biostatistics, University of California, San Francisco noted in an accompanying editorial “fresh evidence provides clues to healthier, not just longer lives.”
However, these results come with a caveat that no conclusion about the amount of food or the role of omega-3 fatty acid supplementation can be made from the study analysis. The authors only studied the blood levels of omega-3s from seafood and found that higher levels increase the chances of living a healthy life.
An epidemiological association does not prove causality, but this study encourages further research in the role of plausible biological mechanisms and interventions related to n3-PUFAs for the maintenance of healthy aging.
According to an estimate, 28 million life-years are lost annually from ill health, disability, or early death due to inadequate omega-3 intake worldwide. In the United States (US), LC omega-3 deficiency is ranked among the top-ten preventable causes of all-cause death.
