Association of Specific Dietary Fats With Total and Cause-Specific Mortality.
Level 3 - non-randomized controlled study
Prospective observational cohort study with repeated measures over follow-up
PubMed 27379574 · doi:10.1001/jamainternmed.2016.2417
What was done
This prospective cohort study analyzed 83,349 women from the Nurses' Health Study (1980 to 2012) and 42,884 men from the Health Professionals Follow-up Study (1986 to 2012) who were free of cardiovascular disease, cancer, and diabetes at baseline. Dietary fat intake was assessed at baseline and updated every 2 to 4 years. Total and cause-specific mortality were tracked across 3,439,954 person-years of follow-up using vital records and the National Death Index.
What was found
During follow-up, 33,304 deaths occurred. After multivariable adjustment, dietary total fat compared with total carbohydrates was inversely associated with total mortality (HR comparing extreme quintiles, 0.84; 95% CI, 0.81-0.88; P < .001 for trend). For specific fat types comparing extreme quintiles, total mortality HRs were 1.08 (95% CI, 1.03-1.14) for saturated fat, 1.13 (95% CI, 1.07-1.18) for trans-fat, 0.81 (95% CI, 0.78-0.84) for polyunsaturated fatty acids (PUFA), and 0.89 (95% CI, 0.84-0.94) for monounsaturated fatty acids (MUFA) (P < .001 for trend for all). Replacing 5% of energy from saturated fats with PUFA or MUFA was associated with estimated reductions in total mortality of 27% (HR, 0.73; 95% CI, 0.70-0.77) and 13% (HR, 0.87; 95% CI, 0.82-0.93), respectively. The HR for omega-6 PUFA was 0.85 (95% CI, 0.81-0.89; P < .001 for trend) and for marine omega-3 PUFA was 0.96 (95% CI, 0.93-1.00; P = .002 for trend).
Why it matters
The study shows that distinct dietary fat types have divergent associations with mortality, supporting dietary guidelines that advise replacing saturated and trans fats with unsaturated fats rather than lowering total fat intake.
Limits
As an observational study, residual and unmeasured confounding cannot be ruled out. Dietary intake was self-reported, which is subject to measurement error. The cohort consists entirely of US health professionals, limiting generalizability to broader or demographically diverse populations. Specific numeric risk estimates for cause-specific mortality outcomes were not reported in the abstract.
Cited by
- supports Large prospective cohort studies, such as the Nurses' Health Study, show that higher intake of omega-6 fatty acids is associated with lower risks of heart disease and cancer.