Conversion of alpha-linolenic acid to eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in young women.
Level 4 - case-series / case-control
Uncontrolled single-arm in vivo metabolic tracer study
PubMed 12323090 · doi:10.1079/BJN2002689
What was done
Women of reproductive age ingested 700 mg of [U-13C]alpha-linolenic acid (ALNA). Concentrations of 13C-labelled fatty acids (ALNA, eicosapentaenoic acid [EPA], docosapentaenoic acid [DPA], and docosahexaenoic acid [DHA]) were measured across plasma lipid classes (cholesteryl ester [CE], triacylglycerol, non-esterified fatty acids, and phosphatidylcholine [PC]) for 21 days. Excretion of 13CO2 on breath was measured over the first 24 hours.
What was found
[13C]ALNA excursion was greatest in CE (224 [SEM 70] micromol/l over 21 d) compared with triacylglycerol (9-fold lower), non-esterified fatty acids (37-fold lower), and PC (7-fold lower). EPA excursion was 42 (SEM 8) micromol/l in PC and 42 (SEM 9) micromol/l in CE. [13C]DPA and [13C]DHA were detected predominantly in PC (18 [SEM 4] and 27 [SEM 7] micromol/l, respectively). Estimated net fractional conversion of ALNA was 21% to EPA, 6% to DPA, and 9% to DHA. Approximately 22% of administered [13C]ALNA was recovered as breath 13CO2 within 24 hours.
Why it matters
This study provides in vivo quantitative estimates of ALNA conversion to long-chain omega-3 fatty acids, demonstrating measurable synthesis of DHA in women of reproductive age.
Limits
The abstract does not state the sample size (n). The trial was uncontrolled with no concurrent male comparison group (comparisons were to historical data). The abstract does not specify participant baseline diet, menstrual cycle phase, or clinical functional outcomes.
Cited by
- supports Premenopausal women convert alpha-linolenic acid (ALA) into EPA and DHA more efficiently than others because estrogen activates the converting enzyme.