Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective observational cohort studies
PubMed 32020162 · doi:10.1093/ajcn/nqz349
What was done
The authors conducted a systematic review and meta-analysis of prospective cohort studies searching MEDLINE and EMBASE through July 31, 2019. They pooled multivariable-adjusted relative risks using random-effects meta-analysis to evaluate associations between linoleic acid exposure (assessed via dietary surveys or adipose/blood biomarkers) and mortality from all causes, cardiovascular disease (CVD), and cancer.
What was found
Thirty-eight studies reporting 44 prospective cohorts were identified, covering 811,069 participants with dietary intake assessment and 65,411 with biomarker measurements. Comparing extreme dietary linoleic acid intake categories (high vs. low), pooled RRs were 0.87 (95% CI: 0.81, 0.94; I2 = 67.9%) for total mortality, 0.87 (95% CI: 0.82, 0.92; I2 = 3.7%) for CVD mortality, and 0.89 (95% CI: 0.85, 0.93; I2 = 0%) for cancer mortality. For each standard deviation increment in adipose or blood linoleic acid concentration, pooled RRs were 0.91 (95% CI: 0.87, 0.95; I2 = 64.1%) for total mortality, 0.89 (95% CI: 0.85, 0.94; I2 = 28.9%) for CVD mortality, and 0.91 (95% CI: 0.84, 0.98; I2 = 26.3%) for cancer mortality.
Why it matters
This review provides quantitative synthesis showing that higher linoleic acid intake and biomarker levels are consistently associated with modestly lower total, cardiovascular, and cancer mortality, arguing against concerns that dietary omega-6 polyunsaturated fatty acids promote premature death.
Limits
All included studies were observational cohorts, precluding causal inference. Substantial heterogeneity was observed for total mortality, which meta-regressions linked to baseline age and dietary assessment methods. Self-reported dietary surveys carry inherent measurement error, though findings were corroborated by objective circulating and adipose tissue biomarkers.
Cited by
- supports Higher levels of linoleic acid in red blood cells and adipose tissue are associated with lower risks of heart disease, cancer mortality, and all-cause mortality.