A low omega-6 polyunsaturated fatty acid (n 6 PUFA) diet increases omega 3 (n3) long chain PUFA status in plasma phospholipids in humans

Key Findings:

Omega 6 LA has increased dramatically in the diet while omega 3 fatty acids have declined. High LA will decrease the amount of ALA that is converted to the longer chain EPA and DHA (as found in fish). Many people do not eat fish and thus strategies have been underway to improve omega 3 status through feeding ALA. In this study, decreasing the level of LA from 4.6 per cent E to 2 per cent E for 4 weeks significantly increased the EPA, DPA and DHA content in plasma, but not erythrocyte phospholipids.  These findings were noted without an increase in n3 LCPUFA intake, and with a decrease in ALA.  Lowering LA also decreased LA and total n6 PUFA content of plasma and erythrocyte phospholipids.  The physiological impact of these findings deserve further assessment.

ABSTRACT:

This study aimed to determine the effect of reducing the dietary linoleic acid (LA) from 5 per cent to less than 2.5 percent energy on n3 long chain PUFA (LCPUFA) status in humans.  Thirty-six participants followed a less than 2.5 per cent E LA diet for 4 weeks.  Nutrient intakes were estimated from diet diaries and blood samples were collected for assessment of fatty acid composition in plasma and erythrocyte phospholipids.  LA intakes were reduced from 4.5 per cent E to 2 per cent E during the low LA intervention while n3 LCPUFA intakes were unchanged.   LA and total n6 PUFA content of plasma and erythrocyte phospholipids were significantly reduced after the low LA diet phase.  The n3 LCPUFA content of plasma phospholipids was significantly increased after the low LA diet compared to baseline (6.22 per cent vs 5.53 per cent).  These data demonstrate that reducing LA intake for 4 weeks increases n3 LCPUFA status in humans in the absence of increased n3 LCPUFA intake.