Abstract
Pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) have been described as dietarybiomarkers of dairy-fat consumption, with varying degrees of reliability between studies. It remainsunclear how the total amount of dietary fat, representing one of the main confounding factors inthese biomarker investigations, affects C15:0 and C17:0 circulating concentrations independent oftheir relative intake. Additionally, it is not clear how changes in the dietary total-fat affects otherfatty acids in circulation. Through two dietary studies with different total-fat levels but maintainingidentical fatty acid compositions, we were able to see how the dietary total-fat affects the fatty acidsin circulation. We saw that there was a statistically significant, proportionate, and robust decrease inthe endogenous C15:0 levels with an increase in dietary total-fat. However, there was no significantchange in the circulating C17:0 concentrations as the total-fat increased. To conclude, the dietarytotal-fat content and fat-type have a very complex influence on the relative compositions of circulatingfatty acids, which are independent of the actual dietary fatty acid composition. Knowing how tomanipulate circulating C15:0 and C17:0 concentrations is far-reaching in nutritional/pathologicalresearch as they highlight a dietary route to attenuate the development of metabolic disease (both byreducing risk and improving prognosis).