Relative validation of a minimally invasive method for estimating the intake of long‐chain omega‐3 fatty acids

Despite having the ability for in vivo synthesis of LC n‐3 PUFA, evidence suggests that our capacity for synthesis is limited and we need to rely on dietary sources. Little data is available on current intakes of EPA and DHA and how this relates to LC n‐3 PUFA status as current methodology is both time consuming and invasive to participants. The aim of this study was therefore to validate minimally invasive methods of assessing dietary intakes and whole blood levels of LC n‐3 PUFA, in order to ascertain whether such methodology could be applied to vulnerable populations. Twenty healthy adults recorded dietary intake for 2‐weeks and subsequently completed a food frequency questionnaire (FFQ) and provided a finger prick blood sample. The FFQ had been specifically designed to estimate intakes of EPA and DHA over the previous three months. Daily intakes of LC n‐3 PUFA from both the diet record and FFQ were calculated using food composition tables. Whole blood fatty acid profiles were determined using the Ideal Omega TM Test by analysis of fatty acyl methyl esters by gas‐liquid chromatography, which has previously been validated against red blood cell polar lipids. Bland Altman analysis showed good agreement between the diet records and FFQ for EPA (mean bias −10mg/d) and DHA (mean bias 30mg/d). In addition, FFQ results for EPA and DHA correlated significantly with the corresponding levels (% total fatty acid) measured using the Rapid Omega Test ( r 2 =0.3, p=0.013 and r 2 =0.3, p=0.015, respectively). The FFQ and Rapid Omega Test are minimally invasive and can be used to obtain quick and reliable estimates of the intake and current status of LC n‐3 PUFA.