Unexpected similarity in RBC DHA and AA levels between bottlenose dolphins and humans.
Level 4 - case-series / case-control
Cross-sectional comparative study using a captive animal cohort and historical human laboratory controls
PubMed 24393427 · doi:10.1016/j.plefa.2013.12.005
What was done
Researchers measured red blood cell (RBC) fatty acid composition using gas chromatography in 35 healthy bottlenose dolphins (*Tursiops truncatus*) housed at two display facilities. They compared these values against historical, deidentified RBC fatty acid data from 11,329 U.S. humans (mean age 58) and estimated dietary EPA and DHA intake in both groups.
What was found
Dolphins had a mean Omega-3 Index of 19.9% compared to 6.0% in humans. RBC EPA was markedly higher in dolphins (15.3% vs. 1.2%), whereas RBC DHA (4.6% in dolphins vs. 4.8% in humans) and arachidonic acid (12.3% vs. 14.5%) were nearly identical. Dolphin linoleic acid was 0.5% compared to 12.5% in humans. Dolphins consumed approximately 60 g/day of EPA+DHA compared to ~0.1 g/day in humans (about 165-fold higher as a percentage of calories).
Why it matters
These findings suggest that RBC membrane incorporation of DHA and arachidonic acid may be tightly constrained or homeostatically regulated across mammalian species, whereas EPA and linoleic acid concentrations directly reflect dietary intake.
Limits
The dolphin sample was small (n=35) and drawn exclusively from managed captive facilities, which may not represent wild dolphin populations. The human comparison group was an unmatched retrospective laboratory database, and the study design cannot elucidate the physiological mechanisms controlling RBC membrane fatty acid saturation limits.
Cited by
- supports Captive dolphins at SeaWorld eating exclusively fish have an Omega-3 Index of approximately 18% to 19%.