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Omega-6 linoleic acid supplements may be harmful in heart disease
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Researchers have found no additional benefits to taking omega-6 linoleic acid supplements in place of saturated fat. Rather, data published in the British Medical Journal suggest an increased risk for all-cause mortality, cardiovascular death and death related to coronary heart disease among those who experienced a recent coronary event.
“In this evaluation of data from the [Sydney Diet Heart Study], selectively increasing the n-6 polyunsaturated fatty acids (PUFA) linoleic acid from safflower oil and safflower polyunsaturated margarine increased rates of death from CVD, CHD, and all-cause mortality compared with a control diet rich in saturated fatty acid from animal fats and common margarines,” the researchers wrote.
They evaluated findings from the Sydney Diet Heart Study (SDHS; 1966-1973) that included 458 men aged 30 to 59 years who had recently had a coronary event. The researchers conducted an updated meta-analysis that included previously unreported data.
The dietary intervention group (n=221) was instructed to increase its PUFA intake to about 15% of food energy, reduce its saturated fatty acid to less than 10% of food energy and reduce its dietary cholesterol intake to 300 mg per day. The control group (n=237) received no dietary instruction.
Compared with controls, the intervention group displayed higher rates of death (all-cause, 11.8% vs. 17.6%; HR=1.62; 95% CI, 1-2.64); CVD (11% vs. 17.2%; HR=1.7; 95% CI, 1.03-2.8); and CHD (10.1% vs. 16.3%; HR=1.74; 95% CI, 1.04-2.92).
After adjustments to the recovered data from SDHS, meta-analysis of linoleic acid intervention trials demonstrated insignificant trends toward an increased risk for death from CHD (HR=1.33; 95% CI, 0.99-1.79) and CVD (HR=1.27; 95% CI, 0.98-1.65).
In an accompanying editorial, Philip C. Calder, BSc(Hons), PhD, DPhil, RNutr, wrote that the new analysis of older data represents important information about the effect of omega-6 PUFAs.
“The findings underscore the need to properly align dietary advice and recommendations with the scientific evidence base,” Calder wrote.
According to researchers, these data could have international implications when dietary advice regarding omega-6 linoleic acid or PUFAs is considered.
For more information:
Calder PC. BMJ. 2013;346:f493.
Ramsden CE. BMJ. 2013;346:e8707.
Disclosure: The researchers report support from the Life Insurance Medical Research Fund of Australia and New Zealand and the Intramural Program of the National Institute on Alcohol Abuse and Alcoholism.