What does the measurement of whole-body fatty acid rate of appearance in plasma by using a fatty acid tracer really mean?
Level 3 - non-randomized controlled study
Prospective non-randomized experimental tracer kinetic study in healthy human volunteers across multiple metabolic conditions.
PubMed 12829627 · doi:10.2337/diabetes.52.7.1641
What was done
Healthy men received an infusion of five [13C]-labeled fatty acids (myristate, palmitate, stearate, oleate, and linoleate) across three metabolic states: basal conditions, epinephrine-stimulated lipolysis, and insulin-inhibited lipolysis. Total plasma free fatty acid (FFA) rate of appearance (Ra) calculated from individual tracers was compared against the measured sum of individual fatty acid Ra, and the Ra profile was compared to subcutaneous adipose tissue triglyceride (TG) composition.
What was found
Calculated total FFA Ra using palmitate, oleate, or linoleate tracers remained within 15% of the measured sum of individual fatty acid Ra under all tested conditions. Stearate consistently underestimated and myristate consistently overestimated total FFA Ra. The plasma fatty acid Ra profile matched the composition of subcutaneous adipose tissue TGs during epinephrine infusion, but diverged during basal and insulin-infused conditions (no specific numerical values reported in abstract).
Why it matters
This study validates the widespread use of single palmitate or oleate tracers to estimate total systemic plasma FFA kinetics across varying physiological states, while indicating that lipid pools other than adipose tissue contribute to systemic fatty acid release in basal and insulin-suppressed conditions.
Limits
The abstract does not state the sample size. Findings are restricted to healthy men and may not generalize to women or individuals with metabolic disorders such as obesity or type 2 diabetes. Exact quantitative variance, statistical confidence intervals, and kinetic rates are omitted from the abstract.
Cited by
- supports Oleic acid is produced endogenously in the human body from the breakdown of white fat during fasting.