Background Cancer and cardiovascular diseases combined account for more than 50% of the overall mortality burden in the USA. Accumulating evidence indicates that saturated fat intake is related to an increase, while unsaturated fat intake is related to a decrease in all-causes mortality. Thus, current US dietary guidelines recommend a shift from saturated to unsaturated fat.

Objective The aim of the present study was to estimate the mortality risk reduction related to a dietary change from saturated fat to an equal amount of mono or polyunsaturated fat intake.

Design The American National health and nutrition examination surveys conducted between 1999 and 2010 were linked to the 2011 national US death registry resulting in an observational prospective mortality study. Proportional hazards Cox models were used to evaluate the association between saturated, mono-unsaturated and poly-unsaturated fat with all-cause, and cause specific mortality. Substitution analysis was conducted to estimate an iso-caloric substitution of 10% of the energy from dietary fat intake applied to the substitution of saturated fat with an equal amount of energy from mono-unsaturated or poly-unsaturated fat.

Inclusion Criteria:

• Included NHANES 1999-2010
• age >= 30 years old

Exclusion Criteria:

• Record not reported in the mortality linked file
• Cancer, type-II diabetes, cardiovascular disease at baseline
• Missing data on covariates used in the model

Apparently healthy US adults age>=30