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Replacement of saturated fat with polyunsaturated fat may reduce CHD risk
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Higher intake of dietary linoleic acid is associated with lower risk for CHD in a dose-response manner, according to results of a systematic review and meta-analysis of prospective cohort studies.
“These data provide support for current recommendations to replace saturated fat with polyunsaturated fat for primary prevention of CHD,” Maryam S. Farvid, PhD, from the department of nutrition, Harvard School of Public Health, and colleagues wrote in Circulation.
The systematic review and meta-analysis focused on 13 prospective cohort studies that assessed the link between dietary intake of linoleic acid, the main polyunsaturated fat found in vegetable oil, nuts and seeds, and the incidence of CHD. Three trials did not report total CHD events, and four provided separate data for men and women, resulting in 14 estimates for total CHD. Two trials did not include data on CHD-related mortality and one reported separate data according to sex, resulting in 12 estimates for CHD mortality. Follow-up ranged from 5.3 years to 30 years across the studies.
Overall, the study population included 310,602 participants and 12,479 total CHD events (5,882 CHD deaths).
Dietary intake of linoleic acid ranged from 1.5% to 6.4% of energy.
Across 10 studies with evaluable data on total CHD events, participants with the highest intake of dietary linoleic acid had a reduced risk for CHD events (pooled RR=0.85; 95% CI, 0.78-0.92 vs. lowest reported intake) in a fixed-effects model. A random-effects model yielded similar results (RR=0.86; 95% CI, 0.76-0.97).
Across the 11 trials that provided evaluable data on CHD mortality, participants with the highest intake of linoleic acid were at reduced risk (pooled RR=0.79; 95% CI, 0.71-0.89 vs. lowest reported intake).
In a dose-response analysis, the researchers observed linear associations between dietary linoleic acid consumption and total CHD events (P=.91 for nonlinearity) and CHD-related mortality (P=.72). Each 5% increment of energy intake from linoleic acid was associated with reduced risk for CHD (RR=0.9; 95% CI, 0.85-0.94) and CHD mortality (RR=0.87; 95% CI, 0.81-0.93).
Analysis of data from eight trials that assessed the substitution of 5% of caloric intake from saturated fats with linoleic acid indicated a 9% reduction in risk in a fixed-effects model (RR=0.91; 95% CI, 0.87-0.96) and a 10% reduction in a random-effects model (OR=0.9; 95% CI; 0.8-1.01). Substitution of 5% of caloric intake from carbohydrates for linoleic acid yielded similar results for total CHD (RR=0.9; 95% CI, 0.85-0.94) and CHD-related mortality (RR=0.87; 95% CI, 0.81-0.94).
According to the researchers, these results provide “robust evidence” of a dose-response relationship between increased linoleic acid intake and reduced CHD risk.
“Randomized clinical trials have shown that replacing saturated fat with polyunsaturated fat reduces total and HDL cholesterol,” Frank B. Hu, MD, PhD, professor of nutrition and epidemiology at Harvard School of Public Health, said in a press release. “Our comprehensive meta-analysis provides clear evidence to support the benefits of consuming polyunsaturated fat as a replacement for saturated fat.”
Disclosure: One researcher reports receiving research support from the California Walnut Commission.
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