Polyunsaturated fatty acids (PUFAs) have been said to possess pleiotropic properties useful against certain chronic diseases, but epidemiological evidence on an association between mortality and the intake of specific PUFAs has so far been limited and contradictory.
Researchers at China's Zhejiang University therefore conducted a study to determine the link between specific dietary PUFAs and mortality in adults in China and the US.
Fats fighting fatalities
They tracked 14,117 participants in the China Health and Nutrition Survey (CHNS) and 36,032 participants in the National Health and Nutrition Examination Survey (NHANES) up through 2011.
They subsequently found that a total of 1,007 deaths had accrued over a median of 14 years in the CHNS, while in the NHANES, 4,826 deaths had accrued over a median of 9.1 years.
They wrote: "Dietary marine omega-3 PUFA was robustly associated with a reduced all-cause mortality in the CHNS. Nevertheless, this inverse relationship was not observed in the NHANES.
"The overall mortality was positively associated with the intake of a-linoleic acid (ALA) the in CHNS, whereas weak inverse associations of ALA and linoleic acid (LA) with all-cause mortality were found in the NHANES."
They added that higher dietary intake of arachidonic acid (AA) was consistently related to lower all-cause mortality in both surveys.
Additionally, PUFA intake at an omega-6 / omega-3 ratio of 6e10 was linked to reduced risk of death in the CHNS.
Different fats for different stats
However, the self-reported dietary intakes measured by the 24-hour dietary recall in the NHANES may not have reflected long-term dietary patterns, and data on cause-specific mortality in the CHNS was lacking.
Furthermore, the researchers did not adjust for trans-fatty acid consumption because of insufficient data. Still, they noted that this was unlikely to alter the results, since trans-fatty acid intake in China is low.
They concluded: "Different sub-types of PUFAs divergently are associated with mortality, and the investigated associations also vary between Chinese and US populations.
"Marine omega-3 PUFA and AA may be more protective for the Chinese population compared with the US population; high consumption of ALA and LA may lower risk of death for the US population, (but) elevate mortality for Chinese population.
"These findings suggest maintaining an omega-6 / omega-3 balanced diet for overall health promotion outcomes. Besides, PUFA consumption with an omega-6 / omega-3 ratio of 6e10 may reduce risk of total mortality for Chinese population."
Source: Clinical Nutrition
https://doi.org/10.1016/j.clnu.2018.02.019 0261-5614
"Polyunsaturated fatty acids intake, omega-6/omega-3 ratio and mortality: Findings from two independent nationwide cohorts"
Authors: Pan Zhuang, et al.