Serum fatty acids as biomarkers of fat intake predict serum cholesterol concentrations in a population-based survey of New Zealand adolescents and adults

Background: The results of randomized controlled trials indicate that the amount and type of dietary fat are important predictors of serum cholesterol concentrations. However, the results of observational studies show weak or no association between dietary fat intake and serum cholesterol. Serum fatty acids are valid biomarkers of fat intake and may improve dietary estimates. Objective: The objective was to ascertain whether serum fatty acids are associated with serum cholesterol concentrations in New Zealand adolescents and adults. Design: The current study was a cross-sectional, national, population-based survey of 2793 New Zealanders aged ≥15 y who participated in the 1997 National Nutrition Survey. The fatty acid composition of serum cholesterol esters, phospholipids, and triacylglycerols was measured. Results: A 1-SD increase in myristic acid (14:0) in serum cholesterol ester, phospholipids, and triacylglycerol corresponded with increases in serum cholesterol of 0.19, 0.13, and 0.10 mmol/L, respectively, after adjustment of the regression analysis for sex, age, body mass index, ethnicity, and smoking. The mean difference in cholesterol concentrations between persons in the highest and the lowest quintiles of serum cholesteryl-myristate was 0.48 mmol/L (P for trend < 0.001). A 1-SD increase in the proportion of linoleic acid (18:2n-6) in serum cholesterol ester, phospholipids, and triacylglycerol corresponded with decreases in serum cholesterol of 0.07, 0.07, and 0.05 mmol/L, respectively. The difference in mean serum cholesterol between the highest and lowest quintiles of cholesteryl-linoleate was 0.18 mmol/L (P for trend = 0.019). Conclusion: Saturated and polyunsaturated fat intakes, measured by using fatty acid biomarkers, are important predictors of serum cholesterol concentrations in New Zealand.