Introduction:
Studies indicate dietary types of fats are associated with risk of coronary heart disease (CHD). Traditional broad classifications may incompletely capture the diversity of fatty acids on CHD. The novel lipid index Dietary Lipophilic Load (DLL) reflects a unique combination of fatty acid fluidity, intermolecular attraction, plus relative fat quantity, while Dietary Lipophilic Index (DLI) is a measure of average fat fluidity, regardless of fat quantity. Thus, we evaluated the association, DLL and DLI, with risk of incident CHD.
METHODS:
Participants included 30,932 women in the Women’s Health Study (WHS), who were free of major chronic diseases at baseline. DLL was calculated by weighted summation of the multiplicative product of each fatty acid’s intakes (g/day) and its melting points (Celcius); DLI was calculated by dividing DLL by total fat intake (g/day). Hazard ratios (HRs) were adjusted for established risk factors, with updated dietary data, and potential mediators. We also investigated hypothesized interactions with C-Reactive Protein (CRP).
RESULTS:
There were 1137 cases of incident CHD in 525,828 person-years over 19 years follow-up. At baseline in over 27,000 women with blood samples, DLL and DLI were not correlated with serum cholesterol, triglyceride, HbA1c, ICAM-1, or CRP biomarkers (r<0.02 for all). In overall multivariate analysis, DLL was associated with higher risk of CHD (extreme quintile HR=1.40, 95%CI: 1.11-1.76, P trend=0.0002), while DLI was not (HR=0.83, 95%CI: 0.67-1.03, P trend=0.75). DLL results were independent beyond adjustment for dietary trans, saturated, monounsaturated, and polyunsaturated fats, nor their aggregate adjustment or the P:S ratio. DLL effects persisted even adjusting for CRP (HR=1.29, P-trend=1 mg/dL for DLL (extreme quintile HR=1.38, 1.02-1.88), than among individuals with low CRP <1 mg/dl for DLL (HR=1.08, 0.68-1.72), with P-interaction<0.0001. Furthermore, CRP also modified DLI, where effects again diverged among higher CRP (HR=0.98, 0.73-1.31) versus low CRP (HR=0.45, 0.27-0.74), with P-interaction<0.0001. Moreover, adjustment of triglycerides, HbA1c, ICAM-1, LDL or HDL cholesterol also did not materially affect overall results.
CONCLUSION:
Results indicate that DLL is associated with increased risk of incident CHD, independent of traditional risk factors, conventional dietary fat classifications, and major CHD biomarkers. Effects of DLL and DLI appear to be modified by levels of CRP. DLL appears to be an important novel dietary fat index that captures additional CHD risk information beyond biomarkers and traditional dietary fat categories. Further studies are warranted.
Geographical clustering of risk factors and lifestyle for coronary heart disease in the Scottish Heart Health Study.