ISSFAL Official Statement Number 6: The importance of measuring blood omega-3 long chain polyunsaturated fatty acid levels in research

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Highlights

  • The ISSFAL Official Statement Number 6 has been approved for publication by the ISSFAL Board of Directors on 9 October 2019.

  • There are many factors associated with n-3 LCPUFA levels and these have been described in a systematic literature review [1].

  • This statement highlights the importance of measuring blood omega-3 long chain polyunsaturated fatty acid (n-3 LCPUFA) levels in research.

Abstract

A statement on measuring blood omega-3 long chain polyunsaturated fatty acid levels was developed and edited based on input from ISSFAL members and accepted by vote of the ISSFAL Board of Directors.

Summary of Statement: Omega-3 long chain polyunsaturated fatty acid (n-3 LCPUFA) levels at baseline and post-intervention should be assessed and reported in future research to evaluate the efficacy of n-3 LCPUFA supplementation: b

ecause; 1. there are numerous factors that affect n-3 LCPUFA levels in humans as described in the systematic literature review [1]; 2. assessing intake of n-3 LCPUFA from the diet and/or supplements is not sufficient to accurately determine n-3 LCPUFA levels in humans; 3. some studies do not provide sufficient doses of n-3 LCPUFA to produce a significant impact on bloodstream/organ content and there is substantial variability in the uptake of n-3 LPCUFA into tissues between individuals. In secondary analyses, clinical trials should consider the influence of fatty acid status (baseline, endpoint and change from baseline to endpoint) on the outcome variables.

Introduction

It is becoming increasingly clear that n-3 LCPUFA play an important role in human health [2]. N-3 LCPUFA have been shown to be important for neurological development [3,4], cardiovascular health [5,6] and there is emerging evidence of their beneficial role in other disease states, including mental health conditions [7].

Several mechanisms have been suggested for these potential health benefits [8], including effects on cell membranes which can influence signal transduction, promotion of neuronal growth, altering neurotransmitter release, and facilitating glucose uptake from the endothelial cells into the brain. N-3 LCPUFA are also important precursors of the eicosanoids and docosanoids, which have anti-thrombotic and vasodilatory effects [8].

The evidence for the above-mentioned potential health benefits are derived from a large number of studies, including both epidemiological/observational studies and baseline data from randomised, controlled trials (RCT). However, many of these studies have failed to include measurements of n-3 LCPUFA levels. This may have serious implications for their ability to draw correct conclusions about the effects of omega-3 on the measured outcome/s.

The recently published systematic literature review [1] highlights that there are many factors associated with the n-3 LCPUFA levels of an individual. Therefore, the aims of the current statement paper are to: 1. recommend that researchers should measure n-3 LCPUFA levels at baseline and post-intervention; 2. report on the full fatty acid results in future research and 3. analyse the results as intention to treat, but also to analyse by the effect of the change of n-3 LCPUFA levels and the change in the outcome variable(s) where possible.

Section snippets

Methods

Professors Barbara Meyer and Renate de Groot proposed to the ISSFAL executive board to write a statement about the importance of measuring n-3 LCPUFA levels in research. After receiving a positive reply from the executive board and support from the ISSFAL board, the procedure for writing ISSFAL statements, as described on the ISSFAL website (http://www.issfal.org/statements/procedures-for-policy-statements), was followed. After a review by the ISSFAL Board, it became clear that a systematic

Terminology

Various terminologies exist in the literature when describing n-3 LCPUFA levels (defined as n-3 PUFA not containing alpha-linolenic acid (ALA, 18:3n-3)) in an individual; including the Holman index; the Lands Highly Unsaturated Fatty Acids (HUFA) [9]; long chain omega-3 PUFA [10] and the HS-Omega-3 Index [11]. The n-3 LCPUFA levels are similar to the afore-mentioned terminologies, and hence n-3 LCPUFA levels are used in the current statement.

Factors affecting n-3 LCPUFA levels

The n-3 LCPUFA levels in an individual are associated

Conclusions

  • 1

    Factors positively associated with the n-3 LCPUFA levels are: age, sex (women less than 50 years of age).

  • 2

    Factors negatively associated with the n-3 LCPUFA levels are: genetics, BMI (if erythrocyte EPA and DHA is less than 6%), smoking and alcohol.

  • 3

    There is inconclusive evidence for the association of waist girth and physical activity with n-3 LCPUFA levels.

  • 4

    There is no convincing evidence that krill oil versus fish oil, or the chemical form of n-3 LCPUFA matters in terms of bioavailability.

  • 5

    It is

Recommendations

The recommendations below are for people of all ages, however the systematic literature review [1] focussed on adults.

  • 1

    It is essential that in all types of research, including cross-sectional, cohort and clinical research, the n-3 LCPUFA levels are measured in biological samples, and this should be done according to appropriate study protocol. So, for cross-sectional studies the biological samples must be measured at one time point and for cohort and clinical intervention studies the biological

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