Effects of fish oil on phospholipid metabolism in human and rat liver studied by 31P NMR spectroscopy in vivo and in vitro.

The effect of omega 3 fatty acids on the metabolism of the normal liver was studied using 31P NMR spectroscopy. Human subjects were examined before and after 1, 3 and 7 days of supplementation with 50 mL fish oil per day (12 g omega 3 fatty acids). 31P NMR spectra (1.6 T) revealed a significant increase in phosphodiester (PDE) to ATP ratios after 1 and 3 days of fish oil. After 7 days, [PDE]/[ATP] ratios at a TR of 1 s had returned to baseline levels, but [PDE]/[ATP] at a TR of 5 s appeared to remain high. Rats were fed diets containing 50% of the energy from fish oil or normal rat chow (controls) for 14 days. 31P NMR liver spectra in vivo (4.7 T) confirmed increased [PDE]/[ATP] in rats fed fish oil compared to controls, although the difference was only statistically significant at a TR of 1.5 s but not at a TR of 8 s. 31P NMR spectra of rat liver extracts (8.7 T) suggested that increased concentrations of glycerophosphocholine and possibly glycerophosphoethanolamine were responsible for rising PDE levels in vivo. Phosphocholine (PC) concentrations were markedly reduced in rat liver after fish oil. The combined rise in glycerophosphocholine and reduction in PC would be consistent with a shift from the phospholipase C to the phospholipase A1/A2 pathway of phosphatidylcholine breakdown after fish oil consumption.